haloperidol (Rx)

Schizophrenia, Psychosis

PO

• Moderate disease, 0.5-2 mg q8-12hr initially
• Severe disease, 3-5 mg q8-12hr initially; not to exceed 30 mg/day

IM lactate (prompt-acting)

• 2-5 mg q4-8hr PRN; may require q1hr in acute agitation; not to exceed 20 mg/day

IM decanoate (depot)

• Initial: IM dose 10-20 times daily PO dose administered monthly; not to exceed 100 mg; if conversion requires initial dose >100 mg, administer in 2 injections (eg, 100 mg initially, then remainder in 3-7 days)
• Maintenance: Monthly dose 10-15 times daily PO dose

IV (Off-label)

• May be needed for ICU delirium; use only haloperidol lactate for IV administration; do not use haloperidol decanoate
• 2-10 mg initially, depending on degree of agitation; if response inadequate, may repeat bolus q15-30min, sequentially doubling initial bolus dose; when calm achieved, administer 25% of last bolus dose q6hr; taper dose after patient is controlled
• Monitor ECG and QT interval (QT prolongation may occur with cumulative doses ≥35 mg; torsades de pointes reported with single doses ≥20 mg)

Tourette Disorder

0.5-2 mg PO q8-12hr initially; if severe symptoms necessitate increased dosage, titrate upward to 3-5 mg PO q8-12hr; if patient remains inadequately controlled, daily doses up to 100 mg have been used (safety not determined)

Schizophrenia, Psychosis/Sedation

<3 years: Safety and efficacy not established

3-12 years (15-40 kg): 0.25-0.5 mg/day PO divided q8-12hr initially; may be increased by 0.5 mg/day every 5-7 days PRN; maintenance: 0.05-0.15 mg/kg/day PO divided q8-12hr  

6-12 years: Lactate (prompt-acting): 1-3 mg IM q4-8hr PRN; not to exceed 0.15 mg/kg/day

>12 years: Moderate disease, 0.5-2 mg PO q8-12hr initially; severe disease, 3-5 mg PO q8-12hr; not to exceed 30 mg/day

Tourette Disorder

<3 years: Safety and efficacy not established

3-12 years: 0.5 mg/day PO initially; dose increased by 0.5 mg every 5-7 days until therapeutic effect achieved, then reduced to lowest effective maintenance level of 0.05-0.075 mg/kg/day PO divided q8-12hr  

>12 years: 0.5-2 mg PO q8-12hr initially; if severe symptoms necessitate increased dosage, titrate upward to 3-5 mg PO q8-12hr; if patient remains inadequately controlled, daily doses up to 100 mg have been used (safety not determined)

Behavioral Disorders

<3 years: Safety and efficacy not established

3-12 years: 0.5 mg/day PO initially; dose increased PRN by 0.5 mg every 5-7 days until therapeutic effect achieved, then reduced to lowest effective maintenance level of 0.05-0.075 mg/kg/day PO divided q8-12hr  

Acute Agitation

<12 years: Safety and efficacy not established

>12 years: 0.5-3 mg PO, repeated in 1 hour PRN; alternatively, 2-5 mg IM, repeated in 1 hr PRN

Schizophrenia, Psychosis

PO: Lower initial doses and more gradual adjustments recommended; 0.25-0.5 mg PO q8-12hr initially

IM lactate (prompt-acting): Lower adult doses and longer dosing intervals recommended compared with typical adult doses

IM decanoate (depot): Lower initial doses and more gradual adjustments recommended; monthly dose 10-15 times daily PO dose

IV (off-label): 0.25-0.5 mg IV q4hr; use only lactate (not decanoate) for IV administration; monitor with ECG for prolonged QT interval

Not approved for dementia-related psychosis, because of increased risk of cardiovascular or infectious related deaths (see Black Box Warnings)

Tourette Disorder

Lower initial doses and more gradual adjustments recommended; 0.25-0.5 mg PO q8-12hr initially

Dosing Considerations

Elderly at higher risk for tardive dyskinesia associated with higher-potency antipsychotic agents such as haloperidol because of higher ratios of dopaminergic blockage to adrenergic/anticholinergic blockade

Contraindicated (14)

• amisulpride

  amisulpride, haloperidol. Either increases toxicity of the other by Other (see comment). Contraindicated. Comment: Increases risk of neuroleptic malignant syndrome.

• disopyramide

  disopyramide and haloperidol both increase QTc interval. Contraindicated.

• eliglustat

  haloperidol increases levels of eliglustat by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. If coadministered with strong or moderate CYP2D6 inhibitors, reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive and intermediate metabolizers; eliglustat is contraindiated if strong or moderate CYP2D6 inhibitors are given concomitantly with strong or moderate CYP3A inhibitors.

• flibanserin

  haloperidol will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of flibanserin with moderate or strong CYP3A4 inhibitors is contraindicated. Severe hypotension or syncope can occur.

• ibutilide

  haloperidol and ibutilide both increase QTc interval. Contraindicated.

• indapamide

  haloperidol and indapamide both increase QTc interval. Contraindicated.

• lefamulin

  lefamulin will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Lefamulin is contraindicated with CYP3A substrates know to prolong the QT interval.

• lomitapide

  haloperidol increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Increases lomitapide levels several folds.

• lonafarnib

  haloperidol will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Lonafarnib is a sensitive CYP3A4 substrate. Coadministration with strong or moderate CYP3A4 inhibitors is contraindicated.

• pentamidine

  haloperidol and pentamidine both increase QTc interval. Contraindicated.

• pimozide

  haloperidol and pimozide both increase QTc interval. Contraindicated.

• procainamide

  haloperidol and procainamide both increase QTc interval. Contraindicated.

• quinidine

  quinidine and haloperidol both increase QTc interval. Contraindicated.

• sotalol

  haloperidol and sotalol both increase QTc interval. Contraindicated.

Serious - Use Alternative (145)

• abametapir

  abametapir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir.

• adagrasib

  adagrasib, haloperidol. Either increases effects of the other by QTc interval. Avoid or Use Alternate Drug. Each drug prolongs the QTc interval, which may increased the risk of Torsade de pointes, other serious arryhthmias, and sudden death. If coadministration unavoidable, more frequent monitoring is recommended for such patients.

• amiodarone

  amiodarone and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• amisulpride

  amisulpride and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. ECG monitoring is recommended if coadministered.

• amitriptyline

  amitriptyline and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• amoxapine

  amoxapine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• anagrelide

  anagrelide and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• apalutamide

  apalutamide will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.

• apomorphine

  haloperidol decreases effects of apomorphine by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• arsenic trioxide

  arsenic trioxide and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• artemether/lumefantrine

  artemether/lumefantrine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  haloperidol and artemether/lumefantrine both increase QTc interval. Avoid or Use Alternate Drug.

• avapritinib

  haloperidol will increase the level or effect of avapritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of avapritinib with moderate CYP3A4 inhibitors. If unable to avoid, reduce avapritinib starting dose. See drug monograph Dosage Modifications.

• axitinib

  haloperidol increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with moderate CYP3A4 inhibitors, monitor closely and reduce dose if necessary .

• benzhydrocodone/acetaminophen

  benzhydrocodone/acetaminophen, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• bosutinib

  haloperidol increases levels of bosutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• bromocriptine

  haloperidol decreases effects of bromocriptine by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• buprenorphine

  buprenorphine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• buprenorphine buccal

  buprenorphine buccal and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• buprenorphine subdermal implant

  buprenorphine subdermal implant and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• buprenorphine transdermal

  buprenorphine transdermal and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• buprenorphine, long-acting injection

  buprenorphine, long-acting injection and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• cabergoline

  haloperidol decreases effects of cabergoline by pharmacodynamic antagonism. Contraindicated.

• calcium/magnesium/potassium/sodium oxybates

  haloperidol, calcium/magnesium/potassium/sodium oxybates. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• carbamazepine

  carbamazepine will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• ceritinib

  ceritinib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.
  
  ceritinib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• chloramphenicol

  chloramphenicol will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• chlorpromazine

  chlorpromazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• citalopram

  citalopram will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Increased risk of serotonin syndrome or neuroleptic malignant syndrome. Potential risk for QT prolongation. ECG monitoring is recommended.
  
  citalopram and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• clarithromycin

  clarithromycin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.
  
  clarithromycin will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• clomipramine

  haloperidol will increase the level or effect of clomipramine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  clomipramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• cobimetinib

  haloperidol will increase the level or effect of cobimetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If concurrent short term (14 days or less) use of moderate CYP3A inhibitors is unavoidable for patients who are taking cobimetinib 60 mg, reduce the cobimetinib dose to 20 mg. After discontinuation of a moderate CYP3A inhibitor, resume cobimetinib 60 mg. Use an alternative to a moderate CYP3A inhibitor in patients who are taking a reduced dose of cobimetinib (40 or 20 mg daily).

• crizotinib

  crizotinib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• dacomitinib

  dacomitinib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid use with CYP2D6 substrates where minimal increases in concentration of the CYP2D6 substrate may lead to serious or life-threatening toxicities.

• desflurane

  desflurane and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• desipramine

  haloperidol will increase the level or effect of desipramine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  desipramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• dofetilide

  dofetilide and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• dopamine

  haloperidol decreases effects of dopamine by pharmacodynamic antagonism. Contraindicated.

• doxepin

  haloperidol will increase the level or effect of doxepin by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  doxepin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• dronedarone

  dronedarone and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• droperidol

  droperidol and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• elacestrant

  haloperidol will increase the level or effect of elacestrant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• eliglustat

  haloperidol increases levels of eliglustat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Moderate CYP3A4 inhibitors are not recommended with eliglustat poor or intermediate metabolizers; reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive metabolizers .
  
  eliglustat and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• encorafenib

  encorafenib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• entrectinib

  haloperidol and entrectinib both increase QTc interval. Avoid or Use Alternate Drug.
  
  haloperidol will increase the level or effect of entrectinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of moderate CYP3A4 inhibitors with entrectinib, a CYP3A4 substrate. If coadministration unavoidable, reduce dose to 200 mg/day for patients aged 12 y or older with BSA >1.50m2. Resume previous entrectinib dose after discontinuing moderate CYP3A inhibitor for 3-5 elimination half-lives.

• epinephrine

  epinephrine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• epinephrine racemic

  epinephrine racemic and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• eribulin

  eribulin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Potential for enhanced QTc-prolonging effects; if concurrent use is necessary then ECG monitoring is recommended.

• erythromycin base

  erythromycin base and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• erythromycin ethylsuccinate

  erythromycin ethylsuccinate and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• erythromycin lactobionate

  erythromycin lactobionate and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• erythromycin stearate

  erythromycin stearate and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• fentanyl

  fentanyl, haloperidol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.
  
  haloperidol will increase the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl intranasal

  fentanyl intranasal, haloperidol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.
  
  haloperidol will increase the level or effect of fentanyl intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transdermal

  fentanyl transdermal, haloperidol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.
  
  haloperidol will increase the level or effect of fentanyl transdermal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transmucosal

  fentanyl transmucosal, haloperidol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.
  
  haloperidol will increase the level or effect of fentanyl transmucosal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fexinidazole

  fexinidazole and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Avoid coadministration of fexinidazole with drugs known to block potassium channels or prolong QT interval.
  
  fexinidazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

• fingolimod

  fingolimod and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• fluconazole

  fluconazole and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• fluoxetine

  fluoxetine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  haloperidol will increase the level or effect of fluoxetine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• fluphenazine

  fluphenazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• formoterol

  formoterol and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• fosphenytoin

  fosphenytoin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• givosiran

  givosiran will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling.

• glasdegib

  haloperidol and glasdegib both increase QTc interval. Avoid or Use Alternate Drug. If coadministration unavoidable, monitor for increased risk of QTc interval prolongation.

• hydrocodone

  hydrocodone, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• hydroxychloroquine sulfate

  hydroxychloroquine sulfate and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• idelalisib

  idelalisib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates

• imipramine

  haloperidol will increase the level or effect of imipramine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  imipramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• indinavir

  indinavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• infigratinib

  haloperidol will increase the level or effect of infigratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• inotuzumab

  inotuzumab and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. If unable to avoid concomitant use, obtain ECGs and electrolytes before and after initiation of any drug known to prolong QTc, and periodically monitor as clinically indicated during treatment.

• isoflurane

  isoflurane and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• ivabradine

  haloperidol will increase the level or effect of ivabradine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of ivabradine with moderate CYP3A4 inhibitors.

• ivosidenib

  ivosidenib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Avoid coadministration of QTc prolonging drugs with ivosidenib or replace with alternate therapies. If coadministration of a QTc prolonging drug is unavoidable, monitor for increased risk of QTc interval prolongation.
  
  ivosidenib will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternate therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.

• ketoconazole

  haloperidol and ketoconazole both increase QTc interval. Avoid or Use Alternate Drug.

• lemborexant

  haloperidol will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of lemborexant with moderate or strong CYP3A inhibitors.

• levodopa

  haloperidol decreases effects of levodopa by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• levoketoconazole

  haloperidol and levoketoconazole both increase QTc interval. Avoid or Use Alternate Drug.

• lisuride

  haloperidol decreases effects of lisuride by pharmacodynamic antagonism. Contraindicated.

• lofepramine

  lofepramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• lopinavir

  lopinavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• lumefantrine

  lumefantrine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  haloperidol and lumefantrine both increase QTc interval. Avoid or Use Alternate Drug.

• lurbinectedin

  haloperidol will increase the level or effect of lurbinectedin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• macimorelin

  macimorelin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Macimorelin causes an increase of ~11 msec in the corrected QT interval. Avoid coadministration with drugs that prolong QT interval, which could increase risk for developing torsade de pointes-type ventricular tachycardia. Allow sufficient washout time of drugs that are known to prolong the QT interval before administering macimorelin.

• maprotiline

  maprotiline and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• methyldopa

  haloperidol decreases effects of methyldopa by pharmacodynamic antagonism. Contraindicated.

• metoclopramide intranasal

  haloperidol, metoclopramide intranasal. Either increases effects of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid use of metoclopramide intranasal or interacting drug, depending on importance of drug to patient.
  
  haloperidol increases toxicity of metoclopramide intranasal by pharmacodynamic synergism. Avoid or Use Alternate Drug. Potential for additive effects, including increased frequency and severity of tardive dyskinesia, other extrapyramidal symptoms, and neuroleptic malignant syndrome.

• midazolam intranasal

  haloperidol will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of moderate CYP3A4 inhibitors with midazolam intranasal causes higher midazolam systemic exposure, which may prolong sedation.

• mifepristone

  mifepristone will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• mobocertinib

  haloperidol will increase the level or effect of mobocertinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If use of moderate CYP3A4 inhibitor unavoidable, reduce mobocertinib dose by ~50% (eg, 160 to 80 mg); closely monitor QTc interval.
  
  mobocertinib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. If coadministration unavoidable, reduce mobocertinib dose and monitor QTc interval more frequently.

• moxifloxacin

  haloperidol and moxifloxacin both increase QTc interval. Avoid or Use Alternate Drug.

• naloxegol

  haloperidol will increase the level or effect of naloxegol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministation of naloxegol with moderate CYP3A4 inhibitors is unavoidable, reduce naloxegol dose to 12.5 mg qDay

• neratinib

  haloperidol will increase the level or effect of neratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of neratinib with strong/moderate CYP3A4 inhibitors.

• nilotinib

  haloperidol and nilotinib both increase QTc interval. Avoid or Use Alternate Drug.

• nortriptyline

  haloperidol will increase the level or effect of nortriptyline by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  nortriptyline and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• octreotide

  haloperidol and octreotide both increase QTc interval. Avoid or Use Alternate Drug.

• octreotide (Antidote)

  haloperidol and octreotide (Antidote) both increase QTc interval. Avoid or Use Alternate Drug.

• olaparib

  haloperidol will increase the level or effect of olaparib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with moderate CYP3A inhibitors cannot be avoided, reduce olaparib dose to 200 mg (capsule) or 150 mg (tablet) PO BID. Do not substitute tablets with capsules.

• olopatadine intranasal

  haloperidol and olopatadine intranasal both increase sedation. Avoid or Use Alternate Drug. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.

• omaveloxolone

  haloperidol will increase the level or effect of omaveloxolone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unavoidable, reduce omaveloxolone dose to 100 mg/day. Closely monitor for adverse effects. If adverse effects emerge, further reduce to 50 mg/day.

• ondansetron

  haloperidol and ondansetron both increase QTc interval. Avoid or Use Alternate Drug. Avoid with congenital long QT syndrome; ECG monitoring recommended with concomitant medications that prolong QT interval, electrolyte abnormalities, CHF, or bradyarrhythmias.

• oxaliplatin

  oxaliplatin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• pacritinib

  haloperidol will increase the level or effect of pacritinib by affecting hepatic enzyme CYP2E1 metabolism. Avoid or Use Alternate Drug.

• panobinostat

  haloperidol and panobinostat both increase QTc interval. Avoid or Use Alternate Drug. Panobinostat is known to significantly prolong QT interval. Panobinostat prescribing information states use with drugs known to prolong QTc is not recommended.

• paroxetine

  paroxetine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• pemigatinib

  haloperidol will increase the level or effect of pemigatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pemigatinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pemigatinib dose.

• perphenazine

  perphenazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• pexidartinib

  haloperidol will increase the level or effect of pexidartinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pexidartinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pexidartinib dose.

• phenytoin

  phenytoin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• pitolisant

  haloperidol and pitolisant both increase QTc interval. Avoid or Use Alternate Drug.

• posaconazole

  posaconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

• pramipexole

  haloperidol decreases effects of pramipexole by pharmacodynamic antagonism. Contraindicated.

• prochlorperazine

  prochlorperazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• promazine

  promazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• promethazine

  promethazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• protriptyline

  protriptyline and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• quinidine

  quinidine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• quinupristin/dalfopristin

  quinupristin/dalfopristin increases levels of haloperidol by decreasing metabolism. Contraindicated. Risk of prolonged QTc interval.

• ribociclib

  ribociclib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• romidepsin

  haloperidol and romidepsin both increase QTc interval. Avoid or Use Alternate Drug.

• ropeginterferon alfa 2b

  ropeginterferon alfa 2b, haloperidol. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Myelosuppressive agents can produce additive myelosuppression. Avoid use and monitor patients receiving the combination for effects of excessive myelosuppression.

• ropinirole

  haloperidol decreases effects of ropinirole by pharmacodynamic antagonism. Contraindicated.

• safinamide

  haloperidol decreases effects of safinamide by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Dopamine antagonists may decrease safinamide effects and exacerbate Parkinson disease symptoms.

• saquinavir

  saquinavir increases levels of haloperidol by QTc interval. Avoid or Use Alternate Drug. Potential for increased toxicity. Increased risk of QT prolongation and cardiac arrhythmias.
  
  saquinavir increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Potential for increased toxicity. Increased risk of QT prolongation and cardiac arrhythmias.

• selinexor

  selinexor, haloperidol. unspecified interaction mechanism. Avoid or Use Alternate Drug. Patients treated with selinexor may experience neurological toxicities. Avoid taking selinexor with other medications that may cause dizziness or confusion.

• selumetinib

  haloperidol will increase the level or effect of selumetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors cannot be avoided, reduce selumetinib dosage (refer to selumetinib monograph for further information). After discontinuation of the strong or moderate CYP3A4 inhibitor for 3 elimination half-lives, resume selumetinib dose that was taken before initiating the inhibitor.

• sevoflurane

  sevoflurane and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• siponimod

  haloperidol will increase the level or effect of siponimod by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of siponimod with a moderate or strong CYP3A4 inhibitor PLUS a moderate or strong CYP2C9 inhibitor is not recommended.
  
  siponimod and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• sodium oxybate

  haloperidol, sodium oxybate. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• sufentanil SL

  sufentanil SL, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration may result in hypotension, profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• tazemetostat

  haloperidol will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of tazemetostat with moderate CYP3A4 inhibitors. If coadministration is unavoidable, reduce tazemetostat current dose (see drug monograph Dosage Modifications).

• tetrabenazine

  tetrabenazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• thioridazine

  haloperidol will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  thioridazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• toremifene

  haloperidol and toremifene both increase QTc interval. Avoid or Use Alternate Drug. Concurrent use of toremifene with agents causing QT prolongation should be avoided. If concomitant use is required it's recommended that toremifene be interrupted. If interruption not possible, patients requiring therapy with a drug that prolongs QT should be closely monitored. ECGs should be obtained for high risk patients.

• trazodone

  trazodone and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• trifluoperazine

  trifluoperazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• trimipramine

  trimipramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• tucatinib

  tucatinib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.

• umeclidinium bromide/vilanterol inhaled

  haloperidol increases toxicity of umeclidinium bromide/vilanterol inhaled by QTc interval. Avoid or Use Alternate Drug. Exercise extreme caution when vilanterol coadministered with drugs that prolong QTc interval; adrenergic agonist effects on the cardiovascular system may be potentiated.

• vandetanib

  haloperidol, vandetanib. Either increases toxicity of the other by QTc interval. Avoid or Use Alternate Drug. Avoid coadministration with drugs known to prolong QT interval; if a drug known to prolong QT interval must be used, more frequent ECG monitoring is recommended.

• vemurafenib

  vemurafenib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Concomitant use of vemurafenib with drugs that prolong QT interval is not recommended.

• venetoclax

  haloperidol will increase the level or effect of venetoclax by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If a moderate CYP3A inhibitor must be used, reduce the venetoclax dose by at least 50%. Monitor more closely for signs of venetoclax toxicities.

• vilanterol/fluticasone furoate inhaled

  haloperidol increases toxicity of vilanterol/fluticasone furoate inhaled by QTc interval. Avoid or Use Alternate Drug. Exercise extreme caution when vilanterol coadministered with drugs that prolong QTc interval; adrenergic agonist effects on the cardiovascular system may be potentiated.

• voxelotor

  voxelotor will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.

• ziprasidone

  haloperidol and ziprasidone both increase QTc interval. Avoid or Use Alternate Drug.

Monitor Closely (432)

• abiraterone

  abiraterone increases levels of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Avoid coadministration of abiraterone with substrates of CYP2D6. If alternative therapy cannot be used, exercise caution and consider a dose reduction of the CYP2D6 substrate.

• abobotulinumtoxinA

  abobotulinumtoxinA increases effects of haloperidol by pharmacodynamic synergism. Use Caution/Monitor. Use of anticholinergic drugs after administration of botulinum toxin-containing products may potentiate systemic anticholinergic effects.

• acalabrutinib

  haloperidol will increase the level or effect of acalabrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease acalabrutinib dose to 100 mg once daily if coadministered with a moderate CYP3A inhibitor.
  
  acalabrutinib, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration may increase risk of myelosuppressive effects.

• aclidinium

  aclidinium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of aclidinium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• acrivastine

  acrivastine and haloperidol both increase sedation. Use Caution/Monitor.

• albuterol

  haloperidol increases and albuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  albuterol and haloperidol both increase QTc interval. Use Caution/Monitor.

• alfentanil

  alfentanil and haloperidol both increase sedation. Use Caution/Monitor.

• alfuzosin

  haloperidol and alfuzosin both increase QTc interval. Use Caution/Monitor.
  
  alfuzosin and haloperidol both increase QTc interval. Use Caution/Monitor.

• almotriptan

  almotriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• alprazolam

  alprazolam and haloperidol both increase sedation. Use Caution/Monitor.

• amifampridine

  haloperidol increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

• amitriptyline

  haloperidol and amitriptyline both increase sedation. Use Caution/Monitor.

• amobarbital

  amobarbital and haloperidol both increase sedation. Use Caution/Monitor.
  
  amobarbital will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• amoxapine

  haloperidol and amoxapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely.
  
  haloperidol and amoxapine both increase sedation. Use Caution/Monitor.

• anticholinergic/sedative combos

  anticholinergic/sedative combos decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  anticholinergic/sedative combos decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of anticholinergic/sedative combos by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• apomorphine

  haloperidol and apomorphine both increase sedation. Use Caution/Monitor.
  
  haloperidol and apomorphine both increase QTc interval. Use Caution/Monitor.

• arformoterol

  haloperidol increases and arformoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  haloperidol and arformoterol both increase QTc interval. Use Caution/Monitor.

• aripiprazole

  aripiprazole and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  aripiprazole and haloperidol both increase sedation. Use Caution/Monitor.
  
  aripiprazole and haloperidol both increase QTc interval. Use Caution/Monitor.

• armodafinil

  haloperidol increases and armodafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• artemether

  haloperidol and artemether both increase QTc interval. Use Caution/Monitor.

• asenapine

  asenapine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and asenapine both increase QTc interval. Use Caution/Monitor.
  
  asenapine and haloperidol both increase sedation. Use Caution/Monitor.

• asenapine transdermal

  asenapine transdermal and haloperidol both increase QTc interval. Use Caution/Monitor.
  
  asenapine transdermal and haloperidol both increase sedation. Use Caution/Monitor.

• atazanavir

  atazanavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• atogepant

  haloperidol will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• atomoxetine

  haloperidol will increase the level or effect of atomoxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  atomoxetine and haloperidol both increase QTc interval. Use Caution/Monitor.

• atracurium

  atracurium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  atracurium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of atracurium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• atropine

  atropine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  atropine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of atropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• atropine IV/IM

  haloperidol increases effects of atropine IV/IM by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
  
  atropine IV/IM decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  atropine IV/IM decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.

• avanafil

  haloperidol will increase the level or effect of avanafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may reduce avanafil clearance increasing systemic exposure to avanafil; increased levels may result in increased associated adverse events; the maximum recommended dose of STENDRA is 50 mg, not to exceed once every 24 hours for patients taking concomitant moderate CYP3A4 inhibitors

• avapritinib

  avapritinib and haloperidol both increase sedation. Use Caution/Monitor.

• azelastine

  azelastine and haloperidol both increase sedation. Use Caution/Monitor.

• azithromycin

  azithromycin and haloperidol both increase QTc interval. Use Caution/Monitor.

• baclofen

  baclofen and haloperidol both increase sedation. Use Caution/Monitor.

• bedaquiline

  haloperidol and bedaquiline both increase QTc interval. Modify Therapy/Monitor Closely. ECG should be monitored closely

• belladonna alkaloids

  belladonna alkaloids decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  belladonna alkaloids decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of belladonna alkaloids by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• belladonna and opium

  belladonna and opium and haloperidol both increase sedation. Use Caution/Monitor.
  
  belladonna and opium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  belladonna and opium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of belladonna and opium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• belzutifan

  belzutifan will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If unable to avoid coadministration of belzutifan with sensitive CYP3A4 substrates, consider increasing the sensitive CYP3A4 substrate dose in accordance with its prescribing information.

• benperidol

  benperidol and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  benperidol and haloperidol both increase sedation. Use Caution/Monitor.

• benzhydrocodone/acetaminophen

  haloperidol will increase the level or effect of benzhydrocodone/acetaminophen by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone [benzhydrocodone is prodrug of hydrocodone]) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.
  
  benzhydrocodone/acetaminophen and haloperidol both increase sedation. Use Caution/Monitor.

• benzphetamine

  haloperidol increases and benzphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• benztropine

  haloperidol increases effects of benztropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic adverse effects may be seen with concurrent use. .

• bosentan

  bosentan will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• bosutinib

  bosutinib and haloperidol both increase QTc interval. Use Caution/Monitor.

• brexanolone

  brexanolone, haloperidol. Either increases toxicity of the other by sedation. Use Caution/Monitor.

• brexpiprazole

  haloperidol will increase the level or effect of brexpiprazole by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP2D6 inhibitor PLUS a strong/moderate CYP3A4 inhibitor.
  
  haloperidol will increase the level or effect of brexpiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP3A4 inhibitor PLUS a strong/moderate CYP2D6 inhibitor.
  
  brexpiprazole and haloperidol both increase sedation. Use Caution/Monitor.

• brimonidine

  brimonidine and haloperidol both increase sedation. Use Caution/Monitor.

• brivaracetam

  brivaracetam and haloperidol both increase sedation. Use Caution/Monitor.

• brompheniramine

  brompheniramine and haloperidol both increase sedation. Use Caution/Monitor.

• buprenorphine

  buprenorphine and haloperidol both increase sedation. Use Caution/Monitor.

• buprenorphine buccal

  buprenorphine buccal and haloperidol both increase sedation. Use Caution/Monitor.

• buprenorphine subdermal implant

  haloperidol will increase the level or effect of buprenorphine subdermal implant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor patients already on buprenorphine subdermal implant who require newly-initiated treatment with CYP3A4 inhibitors for signs and symptoms of overmedication. If the dose of the concomitant CYP3A4 inhibitor cannot be reduced or discontinued, implant removal may be necessary and the patient should then be treated with a buprenorphine dosage form that permits dose adjustments. If a CYP3A4 inhibitor is discontinued in a patient who has been stabilized on buprenorphine, monitor the patient for withdrawal.
  
  buprenorphine subdermal implant and haloperidol both increase sedation. Use Caution/Monitor.

• buprenorphine transdermal

  buprenorphine transdermal and haloperidol both increase sedation. Use Caution/Monitor.

• buprenorphine, long-acting injection

  haloperidol will increase the level or effect of buprenorphine, long-acting injection by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Patients who transfer to buprenorphine long-acting injection from transmucosal buprenorphine coadministered with CYP3A4 inhibitors should be monitored to ensure buprenorphine plasma levels are adequate. Within 2 weeks, if signs and symptoms of buprenorphine toxicity or overdose occur and the concomitant CYP3A4 inhibitor cannot be reduced or discontinued, transition the patient back to a buprenorphine formulation that permits dose adjustments.
  
  haloperidol increases toxicity of buprenorphine, long-acting injection by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of buprenorphine and benzodiazepines or other CNS depressants increases risk of adverse reactions including overdose, respiratory depression, and death. Cessation of benzodiazepines or other CNS depressants is preferred in most cases. In some cases, monitoring at a higher level of care for tapering CNS depressants may be appropriate. In others, gradually tapering a patient off of a prescribed benzodiazepine or other CNS depressant or decreasing to the lowest effective dose may be appropriate.

• bupropion

  bupropion will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• butabarbital

  butabarbital and haloperidol both increase sedation. Use Caution/Monitor.

• butalbital

  butalbital and haloperidol both increase sedation. Use Caution/Monitor.

• butorphanol

  butorphanol and haloperidol both increase sedation. Use Caution/Monitor.

• cabozantinib

  haloperidol will increase the level or effect of cabozantinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• caffeine

  haloperidol increases and caffeine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• cannabidiol

  haloperidol will increase the level or effect of cannabidiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider reducing the cannabidiol dose when coadministered with a moderate CYP3A4 inhibitor.

• capecitabine

  capecitabine and haloperidol both increase QTc interval. Use Caution/Monitor.

• carbamazepine

  carbamazepine decreases levels of haloperidol by increasing metabolism. Use Caution/Monitor.

• carbinoxamine

  carbinoxamine and haloperidol both increase sedation. Use Caution/Monitor.

• carisoprodol

  carisoprodol and haloperidol both increase sedation. Use Caution/Monitor.

• carvedilol

  haloperidol will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• celecoxib

  celecoxib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• cenobamate

  cenobamate will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.

• chloral hydrate

  chloral hydrate and haloperidol both increase sedation. Use Caution/Monitor.

• chlordiazepoxide

  chlordiazepoxide and haloperidol both increase sedation. Use Caution/Monitor.

• chloroquine

  chloroquine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  chloroquine increases toxicity of haloperidol by QTc interval. Use Caution/Monitor.

• chlorpheniramine

  chlorpheniramine and haloperidol both increase sedation. Use Caution/Monitor.

• chlorpromazine

  chlorpromazine and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  chlorpromazine and haloperidol both increase sedation. Use Caution/Monitor.

• chlorzoxazone

  chlorzoxazone and haloperidol both increase sedation. Use Caution/Monitor.

• cimetidine

  cimetidine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• cinnarizine

  cinnarizine and haloperidol both increase sedation. Use Caution/Monitor.

• ciprofloxacin

  ciprofloxacin and haloperidol both increase QTc interval. Use Caution/Monitor. Ciprofloxacin elicits minimal effects on QT interval. Caution if used in combination with other drugs known to affect QT interval or in patients with other risk factors.

• cisatracurium

  cisatracurium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  cisatracurium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of cisatracurium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• clemastine

  clemastine and haloperidol both increase sedation. Use Caution/Monitor.

• clobazam

  clobazam will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Lower doses of drugs metabolized by CYP2D6 may be required when used concomitantly.

• clomipramine

  haloperidol and clomipramine both increase sedation. Use Caution/Monitor.

• clonazepam

  clonazepam and haloperidol both increase sedation. Use Caution/Monitor.

• clonidine

  clonidine, haloperidol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
  
  clonidine increases toxicity of haloperidol by Other (see comment). Use Caution/Monitor. Comment: High doses of clonidine IV may increase arrhythmogenic potential (QT-prolongation, ventricular fibrillation) of high dose haloperidol IV in patients experiencing alcoholic delirium.

• clorazepate

  clorazepate and haloperidol both increase sedation. Use Caution/Monitor.

• clozapine

  clozapine and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  clozapine and haloperidol both increase sedation. Use Caution/Monitor.
  
  haloperidol and clozapine both increase QTc interval. Use Caution/Monitor.

• cobicistat

  cobicistat will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• codeine

  haloperidol decreases effects of codeine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Prevents conversion of codeine to its active metabolite morphine.
  
  codeine and haloperidol both increase sedation. Use Caution/Monitor.

• conivaptan

  conivaptan will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• crizotinib

  crizotinib increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A. ECG monitoring is recommended, along with drugs that may prolong the QT interval.

• crofelemer

  crofelemer increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.

• cyclizine

  cyclizine and haloperidol both increase sedation. Use Caution/Monitor.
  
  cyclizine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  cyclizine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of cyclizine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• cyclobenzaprine

  cyclobenzaprine and haloperidol both increase sedation. Use Caution/Monitor.
  
  cyclobenzaprine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  cyclobenzaprine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of cyclobenzaprine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• cyproheptadine

  cyproheptadine and haloperidol both increase sedation. Use Caution/Monitor.

• dabrafenib

  dabrafenib will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.
  
  dabrafenib and haloperidol both increase QTc interval. Use Caution/Monitor.

• dantrolene

  dantrolene and haloperidol both increase sedation. Use Caution/Monitor.

• daridorexant

  haloperidol will increase the level or effect of daridorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Daridorexant dose should not exceed 25 mg per night when coadministered with moderate CYP3A4 inhibitors.
  
  haloperidol and daridorexant both increase sedation. Modify Therapy/Monitor Closely. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.

• darifenacin

  darifenacin will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  darifenacin decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  darifenacin decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of darifenacin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• darunavir

  darunavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• dasatinib

  dasatinib and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• deferasirox

  deferasirox will increase the level or effect of haloperidol by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• deflazacort

  haloperidol will increase the level or effect of deflazacort by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease deflazacort dose to one-third of the recommended dose if coadministered with moderate or strong CYP3A4 inhibitors.

• degarelix

  haloperidol and degarelix both increase QTc interval. Use Caution/Monitor.

• desflurane

  desflurane and haloperidol both increase sedation. Use Caution/Monitor.

• desipramine

  haloperidol and desipramine both increase sedation. Use Caution/Monitor.

• desvenlafaxine

  desvenlafaxine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Desvenlafaxine inhibits CYP2D6; with higher desvenlafaxine doses (ie, 400 mg) decrease the CYP2D6 substrate dose by up to 50%; no dosage adjustment needed with desvenlafaxine doses <100 mg

• deutetrabenazine

  haloperidol and deutetrabenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely. The risk for parkinsonism, neuroleptic malignant syndrome, and akathisia may be increased by concomitant use of deutetrabenazine and dopamine antagonists or antipsychotics.
  
  haloperidol and deutetrabenazine both increase sedation. Use Caution/Monitor.
  
  haloperidol and deutetrabenazine both increase QTc interval. Use Caution/Monitor. At the maximum recommended dose, deutetrabenazine does not prolong QT interval to a clinically relevant extent. Certain circumstances may increase risk of torsade de pointes and/or sudden death in association with drugs that prolong the QTc interval (eg, bradycardia, hypokalemia or hypomagnesemia, coadministration with other drugs that prolong QTc interval, presence of congenital QT prolongation).

• dexchlorpheniramine

  dexchlorpheniramine and haloperidol both increase sedation. Use Caution/Monitor.

• dexfenfluramine

  haloperidol increases and dexfenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dexmedetomidine

  dexmedetomidine and haloperidol both increase sedation. Use Caution/Monitor.

• dexmethylphenidate

  haloperidol increases and dexmethylphenidate decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dextroamphetamine

  haloperidol increases and dextroamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dextromethorphan

  dextromethorphan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• dextromoramide

  dextromoramide and haloperidol both increase sedation. Use Caution/Monitor.

• diamorphine

  diamorphine and haloperidol both increase sedation. Use Caution/Monitor.

• diazepam

  diazepam and haloperidol both increase sedation. Use Caution/Monitor.

• diazepam intranasal

  haloperidol will increase the level or effect of diazepam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong or moderate CYP3A4 inhibitors may decrease rate of diazepam elimination, thereby increasing adverse reactions to diazepam.

• dicyclomine

  dicyclomine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  dicyclomine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of dicyclomine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• diethylpropion

  haloperidol increases and diethylpropion decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• difelikefalin

  difelikefalin and haloperidol both increase sedation. Use Caution/Monitor.

• difenoxin hcl

  difenoxin hcl and haloperidol both increase sedation. Use Caution/Monitor.

• dihydroergotamine

  dihydroergotamine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• dimenhydrinate

  dimenhydrinate and haloperidol both increase sedation. Use Caution/Monitor.

• diphenhydramine

  diphenhydramine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  diphenhydramine and haloperidol both increase sedation. Use Caution/Monitor.
  
  diphenhydramine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  diphenhydramine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• diphenoxylate hcl

  diphenoxylate hcl and haloperidol both increase sedation. Use Caution/Monitor.

• dipipanone

  dipipanone and haloperidol both increase sedation. Use Caution/Monitor.

• dobutamine

  haloperidol increases and dobutamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dolasetron

  dolasetron and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• donepezil

  donepezil and haloperidol both increase QTc interval. Use Caution/Monitor.

• donepezil transdermal

  donepezil transdermal, haloperidol. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.

• dopamine

  haloperidol increases and dopamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dopexamine

  haloperidol increases and dopexamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dosulepin

  haloperidol and dosulepin both increase sedation. Use Caution/Monitor.

• doxepin

  haloperidol and doxepin both increase sedation. Use Caution/Monitor.

• doxylamine

  doxylamine and haloperidol both increase sedation. Use Caution/Monitor.

• dronedarone

  dronedarone will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• droperidol

  droperidol and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  droperidol and haloperidol both increase sedation. Use Caution/Monitor.

• duvelisib

  duvelisib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with duvelisib increases AUC of a sensitive CYP3A4 substrate which may increase the risk of toxicities of these drugs. Consider reducing the dose of the sensitive CYP3A4 substrate and monitor for signs of toxicities of the coadministered sensitive CYP3A substrate.

• efavirenz

  efavirenz will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  efavirenz and haloperidol both increase QTc interval. Use Caution/Monitor.

• elagolix

  elagolix decreases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.

• eletriptan

  eletriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• eliglustat

  eliglustat increases levels of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the concomitant drug and titrate to clinical effect.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.
  
  elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP2D6 inhibitor; caution with CYP2D6 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

• encorafenib

  encorafenib, haloperidol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.

• enzalutamide

  enzalutamide will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ephedrine

  haloperidol increases and ephedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• epinephrine

  haloperidol increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• epinephrine racemic

  haloperidol increases and epinephrine racemic decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• ergoloid mesylates

  ergoloid mesylates, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• ergotamine

  ergotamine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• escitalopram

  haloperidol and escitalopram both increase QTc interval. Use Caution/Monitor.
  
  escitalopram increases toxicity of haloperidol by QTc interval. Use Caution/Monitor.

• esketamine intranasal

  esketamine intranasal, haloperidol. Either increases toxicity of the other by sedation. Use Caution/Monitor.

• estazolam

  estazolam and haloperidol both increase sedation. Use Caution/Monitor.

• ethanol

  haloperidol and ethanol both increase sedation. Use Caution/Monitor.

• etomidate

  etomidate and haloperidol both increase sedation. Use Caution/Monitor.

• etravirine

  etravirine will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ezogabine

  ezogabine, haloperidol. Either increases toxicity of the other by QTc interval. Use Caution/Monitor. Slight and transient QT-prolongation observed with ezogabine, particularly when dose titrated to 1200 mg/day. QT interval should be monitored when ezogabine is prescribed with agents known to increase QT interval.

• fedratinib

  fedratinib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.
  
  fedratinib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.

• fenfluramine

  haloperidol increases and fenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• fentanyl

  fentanyl, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• fesoterodine

  fesoterodine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  fesoterodine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• finerenone

  haloperidol will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor serum potassium during initiation and dosage adjustment of either finererone or moderate CYP3A4 inhibitors. Adjust finererone dosage as needed.

• flavoxate

  flavoxate decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  flavoxate decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of flavoxate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• flecainide

  haloperidol will increase the level or effect of flecainide by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised.
  
  flecainide and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• flibanserin

  flibanserin, haloperidol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• fluoxetine

  fluoxetine and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• fluphenazine

  fluphenazine and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  fluphenazine and haloperidol both increase sedation. Use Caution/Monitor.

• flurazepam

  flurazepam and haloperidol both increase sedation. Use Caution/Monitor.

• fluvoxamine

  fluvoxamine and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• formoterol

  haloperidol increases and formoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• foscarnet

  foscarnet and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• fostemsavir

  haloperidol and fostemsavir both increase QTc interval. Use Caution/Monitor. QTc prolongation reported with higher than recommended doses of fostemsavir.

• frovatriptan

  frovatriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• gadobenate

  gadobenate and haloperidol both increase QTc interval. Use Caution/Monitor.

• ganaxolone

  haloperidol and ganaxolone both increase sedation. Use Caution/Monitor.

• gemifloxacin

  haloperidol and gemifloxacin both increase QTc interval. Use Caution/Monitor.

• gemtuzumab

  haloperidol and gemtuzumab both increase QTc interval. Use Caution/Monitor.

• gilteritinib

  gilteritinib and haloperidol both increase QTc interval. Use Caution/Monitor.

• glycerol phenylbutyrate

  haloperidol decreases effects of glycerol phenylbutyrate by Other (see comment). Use Caution/Monitor. Comment: Haloperidol may induce hyperammonemia; monitor ammonia levels closely when coadministered with glycerol phenylbutyrate.

• glycopyrrolate

  haloperidol increases effects of glycopyrrolate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• glycopyrrolate inhaled

  glycopyrrolate inhaled decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  glycopyrrolate inhaled decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of glycopyrrolate inhaled by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• glycopyrronium tosylate topical

  glycopyrronium tosylate topical, haloperidol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration of glycopyrronium tosylate topical with other anticholinergic medications may result in additive anticholinergic adverse effects.

• goserelin

  goserelin increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Increases risk of torsades de pointes.

• granisetron

  granisetron and haloperidol both increase QTc interval. Use Caution/Monitor.

• guanfacine

  guanfacine, haloperidol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
  
  haloperidol will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.

• henbane

  henbane decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  henbane decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of henbane by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• histrelin

  histrelin increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Increases risk of torsades de pointes.

• homatropine

  homatropine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  homatropine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of homatropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• hydrocodone

  haloperidol will increase the level or effect of hydrocodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.

• hydromorphone

  haloperidol will increase the level or effect of hydromorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  hydromorphone and haloperidol both increase sedation. Use Caution/Monitor.

• hydroxyzine

  hydroxyzine and haloperidol both increase sedation. Use Caution/Monitor.
  
  hydroxyzine and haloperidol both increase QTc interval. Use Caution/Monitor.

• hyoscyamine

  hyoscyamine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  hyoscyamine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• hyoscyamine spray

  haloperidol increases effects of hyoscyamine spray by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
  
  hyoscyamine spray decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  hyoscyamine spray decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.

• ibrutinib

  haloperidol increases levels of ibrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate CYP3A4 inhibitors, reduce ibrutinib dose to 280 mg qDay (B-cell malignancies) or 420 mg qDay (graft versus host disease). After CYP3A inhibitor discontinuation, resume previous dose of ibrutinib.

• ifosfamide

  haloperidol decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• iloperidone

  haloperidol will increase the level or effect of iloperidone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and iloperidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and iloperidone both increase QTc interval. Modify Therapy/Monitor Closely.
  
  haloperidol and iloperidone both increase sedation. Use Caution/Monitor.
  
  iloperidone increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.

• imatinib

  imatinib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• imipramine

  haloperidol and imipramine both increase sedation. Use Caution/Monitor.

• incobotulinumtoxinA

  haloperidol, incobotulinumtoxinA. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Use of anticholinergic drugs after administration of botulinum toxin-containing products may potentiate systemic anticholinergic effects.

• indacaterol, inhaled

  indacaterol, inhaled, haloperidol. QTc interval. Use Caution/Monitor. Drugs that are known to prolong the QTc interval may have an increased the risk of ventricular arrhythmias.

• ipratropium

  ipratropium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  ipratropium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of ipratropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• isavuconazonium sulfate

  haloperidol will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• isoniazid

  isoniazid will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• isoproterenol

  haloperidol increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• isradipine

  haloperidol and isradipine both increase QTc interval. Use Caution/Monitor.

• istradefylline

  istradefylline will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.

• itraconazole

  haloperidol and itraconazole both increase QTc interval. Modify Therapy/Monitor Closely.
  
  itraconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ivacaftor

  haloperidol will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• ivosidenib

  haloperidol will increase the level or effect of ivosidenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration with moderate CYP3A4 inhibitors may increase ivosidenib plasma concentrations, thus increasing the risk of QTc prolongation. Monitor for increased risk of QTc interval prolongation.

• ketamine

  ketamine and haloperidol both increase sedation. Use Caution/Monitor.

• ketoconazole

  ketoconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ketotifen, ophthalmic

  haloperidol and ketotifen, ophthalmic both increase sedation. Use Caution/Monitor.

• lapatinib

  haloperidol and lapatinib both increase QTc interval. Modify Therapy/Monitor Closely.

• lasmiditan

  lasmiditan, haloperidol. Either increases effects of the other by sedation. Use Caution/Monitor. Coadministration of lasmiditan and other CNS depressant drugs, including alcohol have not been evaluated in clinical studies. Lasmiditan may cause sedation, as well as other cognitive and/or neuropsychiatric adverse reactions.

• lemborexant

  lemborexant, haloperidol. Either increases effects of the other by sedation. Modify Therapy/Monitor Closely. Dosage adjustment may be necessary if lemborexant is coadministered with other CNS depressants because of potentially additive effects.

• lenacapavir

  lenacapavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.

• lenvatinib

  haloperidol and lenvatinib both increase QTc interval. Use Caution/Monitor. Lenvatinib prescribing information recommends monitoring ECG closely when coadministered with QT prolonging drugs.

• letermovir

  letermovir increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• leuprolide

  leuprolide increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Increases risk of torsades de pointes.

• levalbuterol

  haloperidol increases and levalbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• levamlodipine

  haloperidol will increase the level or effect of levamlodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate and strong CYP3A inhibitors results in increased systemic exposure to amlodipine and may require dose reduction. Monitor for symptoms of hypotension and edema when amlodipine is coadministered with CYP3A inhibitors to determine the need for dose adjustment.

• levofloxacin

  haloperidol and levofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.

• levoketoconazole

  levoketoconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• levomilnacipran

  levomilnacipran, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• levorphanol

  levorphanol and haloperidol both increase sedation. Use Caution/Monitor.

• linezolid

  linezolid, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• lisdexamfetamine

  haloperidol increases and lisdexamfetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• lithium

  lithium, haloperidol. Other (see comment). Use Caution/Monitor. Comment: Risk of neurotoxicity. Multiple mechanisms involved.
  
  lithium, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  lithium and haloperidol both increase QTc interval. Use Caution/Monitor.

• lofepramine

  haloperidol will increase the level or effect of lofepramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and lofepramine both increase sedation. Use Caution/Monitor.

• lofexidine

  haloperidol and lofexidine both increase sedation. Use Caution/Monitor.

• loprazolam

  loprazolam and haloperidol both increase sedation. Use Caution/Monitor.

• lorazepam

  lorazepam and haloperidol both increase sedation. Use Caution/Monitor.

• lorcaserin

  lorcaserin will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  lorcaserin, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• lorlatinib

  lorlatinib will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• lormetazepam

  lormetazepam and haloperidol both increase sedation. Use Caution/Monitor.

• loxapine

  haloperidol and loxapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and loxapine both increase sedation. Use Caution/Monitor.

• loxapine inhaled

  haloperidol and loxapine inhaled both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and loxapine inhaled both increase sedation. Use Caution/Monitor.

• lumateperone

  haloperidol will increase the level or effect of lumateperone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce lumateperone dose to 21 mg/day if coadministered with moderate CYP3A4 inhibitors.

• lurasidone

  lurasidone, haloperidol. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Potential for increased CNS depressant effects when used concurrently; monitor for increased adverse effects and toxicity.

• maprotiline

  haloperidol and maprotiline both increase sedation. Use Caution/Monitor.

• maraviroc

  maraviroc will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• marijuana

  marijuana will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and marijuana both increase sedation. Use Caution/Monitor.

• mavacamten

  haloperidol will increase the level or effect of mavacamten by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Inititiation of moderate CYP3A4 inhibitors may require decreased mavacamten dose.

• meclizine

  meclizine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  meclizine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of meclizine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• mefloquine

  haloperidol and mefloquine both increase QTc interval. Use Caution/Monitor.
  
  haloperidol will increase the level or effect of mefloquine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• melatonin

  haloperidol and melatonin both increase sedation. Use Caution/Monitor.

• meperidine

  meperidine and haloperidol both increase sedation. Use Caution/Monitor.
  
  meperidine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• meprobamate

  haloperidol and meprobamate both increase sedation. Use Caution/Monitor.

• metaproterenol

  haloperidol increases and metaproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• metaxalone

  metaxalone and haloperidol both increase sedation. Use Caution/Monitor.

• methadone

  haloperidol and methadone both increase QTc interval. Modify Therapy/Monitor Closely.
  
  methadone and haloperidol both increase sedation. Use Caution/Monitor.
  
  methadone, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• methamphetamine

  haloperidol will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• methocarbamol

  methocarbamol and haloperidol both increase sedation. Use Caution/Monitor.

• methscopolamine

  methscopolamine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  methscopolamine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of methscopolamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• methylenedioxymethamphetamine

  haloperidol increases and methylenedioxymethamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• methylergonovine

  methylergonovine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• methylphenidate

  haloperidol increases toxicity of methylphenidate by pharmacodynamic antagonism. Use Caution/Monitor. Closely monitor for signs of altered clinical response to either methylphenidate or an antipsychotic when using these drugs in combination.

• metoclopramide

  haloperidol and metoclopramide both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.

• metoprolol

  haloperidol will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• mexiletine

  haloperidol will increase the level or effect of mexiletine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised
  
  haloperidol and mexiletine both increase QTc interval. Use Caution/Monitor.

• midazolam

  midazolam and haloperidol both increase sedation. Use Caution/Monitor.

• midazolam intranasal

  midazolam intranasal, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase the risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.

• midodrine

  haloperidol increases and midodrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• mifepristone

  mifepristone, haloperidol. QTc interval. Modify Therapy/Monitor Closely. Use alternatives if available.

• milnacipran

  milnacipran, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• mirabegron

  mirabegron will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• mirtazapine

  haloperidol and mirtazapine both increase sedation. Use Caution/Monitor.
  
  mirtazapine and haloperidol both increase QTc interval. Use Caution/Monitor.

• mitotane

  mitotane decreases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.

• modafinil

  haloperidol increases and modafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• morphine

  haloperidol will increase the level or effect of morphine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  morphine and haloperidol both increase sedation. Use Caution/Monitor.

• motherwort

  haloperidol and motherwort both increase sedation. Use Caution/Monitor.

• moxonidine

  haloperidol and moxonidine both increase sedation. Use Caution/Monitor.

• nabilone

  haloperidol and nabilone both increase sedation. Use Caution/Monitor.

• nafcillin

  nafcillin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• nalbuphine

  nalbuphine and haloperidol both increase sedation. Use Caution/Monitor.

• naldemedine

  haloperidol increases levels of naldemedine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor naldemedine for potential adverse effects if coadministered with strong or moderate CYP3A4 inhibitors.

• naratriptan

  naratriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• nebivolol

  haloperidol will increase the level or effect of nebivolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• nefazodone

  nefazodone will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• nelfinavir

  nelfinavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• nilotinib

  nilotinib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• norepinephrine

  haloperidol increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• nortriptyline

  haloperidol and nortriptyline both increase sedation. Use Caution/Monitor.

• ofloxacin

  haloperidol and ofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.

• olanzapine

  haloperidol and olanzapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and olanzapine both increase sedation. Use Caution/Monitor.
  
  haloperidol and olanzapine both increase QTc interval. Use Caution/Monitor.

• oliceridine

  haloperidol will increase the level or effect of oliceridine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.
  
  oliceridine, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• olodaterol inhaled

  haloperidol and olodaterol inhaled both increase QTc interval. Use Caution/Monitor. Drugs that prolong the QTc interval and may potentiate the effects of beta2 agonists on the cardiovascular system; increased risk of ventricular arrhythmias

• onabotulinumtoxinA

  onabotulinumtoxinA decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  onabotulinumtoxinA decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of onabotulinumtoxinA by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• opium tincture

  opium tincture and haloperidol both increase sedation. Use Caution/Monitor.

• orphenadrine

  orphenadrine and haloperidol both increase sedation. Use Caution/Monitor.

• osilodrostat

  osilodrostat and haloperidol both increase QTc interval. Use Caution/Monitor.

• osimertinib

  osimertinib and haloperidol both increase QTc interval. Use Caution/Monitor. Conduct periodic monitoring with ECGs and electrolytes in patients taking drugs known to prolong the QTc interval.

• oxaliplatin

  oxaliplatin will increase the level or effect of haloperidol by Other (see comment). Use Caution/Monitor. Monitor for ECG changes if therapy is initiated in patients with drugs known to prolong QT interval.

• oxazepam

  oxazepam and haloperidol both increase sedation. Use Caution/Monitor.

• oxybutynin

  oxybutynin decreases effects of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  oxybutynin decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  haloperidol increases effects of oxybutynin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• oxybutynin topical

  oxybutynin topical decreases effects of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  oxybutynin topical decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  haloperidol increases effects of oxybutynin topical by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• oxybutynin transdermal

  oxybutynin transdermal decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  oxybutynin transdermal decreases effects of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of oxybutynin transdermal by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• oxycodone

  haloperidol will increase the level or effect of oxycodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  oxycodone and haloperidol both increase sedation. Use Caution/Monitor.

• oxymorphone

  haloperidol will increase the level or effect of oxymorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  oxymorphone and haloperidol both increase sedation. Use Caution/Monitor.

• ozanimod

  ozanimod and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely. The potential additive effects on heart rate, treatment with ozanimod should generally not be initiated in patients who are concurrently treated with QT prolonging drugs with known arrhythmogenic properties.

• palbociclib

  haloperidol will increase the level or effect of palbociclib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• paliperidone

  haloperidol and paliperidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and paliperidone both increase QTc interval. Modify Therapy/Monitor Closely.
  
  haloperidol and paliperidone both increase sedation. Use Caution/Monitor.

• pancuronium

  pancuronium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  pancuronium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of pancuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• papaveretum

  papaveretum and haloperidol both increase sedation. Use Caution/Monitor.

• papaverine

  haloperidol and papaverine both increase sedation. Use Caution/Monitor.

• parecoxib

  parecoxib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• paroxetine

  haloperidol will increase the level or effect of paroxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and paroxetine both increase QTc interval. Modify Therapy/Monitor Closely.
  
  paroxetine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• pasireotide

  haloperidol and pasireotide both increase QTc interval. Modify Therapy/Monitor Closely.

• pazopanib

  haloperidol and pazopanib both increase QTc interval. Use Caution/Monitor.

• peginterferon alfa 2b

  peginterferon alfa 2b, haloperidol. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.

• pentazocine

  pentazocine and haloperidol both increase sedation. Use Caution/Monitor.

• pentobarbital

  pentobarbital and haloperidol both increase sedation. Use Caution/Monitor.

• perphenazine

  perphenazine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and perphenazine both increase sedation. Use Caution/Monitor.

• phendimetrazine

  haloperidol increases and phendimetrazine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenelzine

  phenelzine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• phenobarbital

  phenobarbital and haloperidol both increase sedation. Use Caution/Monitor.
  
  phenobarbital will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• phentermine

  haloperidol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenylephrine

  haloperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenylephrine PO

  haloperidol increases and phenylephrine PO decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. .

• pholcodine

  haloperidol and pholcodine both increase sedation. Use Caution/Monitor.

• pimozide

  haloperidol and pimozide both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and pimozide both increase sedation. Use Caution/Monitor.

• pirbuterol

  haloperidol increases and pirbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• posaconazole

  haloperidol and posaconazole both increase QTc interval. Modify Therapy/Monitor Closely.

• pralidoxime

  pralidoxime decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  pralidoxime decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of pralidoxime by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• primaquine

  primaquine and haloperidol both increase QTc interval. Use Caution/Monitor.

• primidone

  primidone and haloperidol both increase sedation. Use Caution/Monitor.
  
  primidone will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• procarbazine

  procarbazine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• prochlorperazine

  haloperidol and prochlorperazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and prochlorperazine both increase sedation. Use Caution/Monitor.

• promethazine

  haloperidol and promethazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  promethazine and haloperidol both increase sedation. Use Caution/Monitor.
  
  promethazine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• propafenone

  haloperidol will increase the level or effect of propafenone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised.
  
  haloperidol and propafenone both increase QTc interval. Use Caution/Monitor.

• propantheline

  propantheline decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  propantheline decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of propantheline by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• propofol

  propofol and haloperidol both increase sedation. Use Caution/Monitor.

• propranolol

  haloperidol will increase the level or effect of propranolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised. Coadministration of beta-blockers and haloperidol may cause an unexpected severe hypotensive reaction.

• propylhexedrine

  haloperidol increases and propylhexedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• protriptyline

  haloperidol and protriptyline both increase sedation. Use Caution/Monitor.

• quazepam

  quazepam and haloperidol both increase sedation. Use Caution/Monitor.

• quetiapine

  haloperidol and quetiapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and quetiapine both increase sedation. Use Caution/Monitor.
  
  quetiapine, haloperidol. Either increases toxicity of the other by QTc interval. Use Caution/Monitor. Avoid use with drugs that prolong QT and in patients with risk factors for prolonged QT interval. Postmarketing cases show QT prolongation with overdose in patients with concomitant illness or with drugs known to cause electrolyte imbalance or prolong QT.

• quinacrine

  quinacrine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• quinine

  haloperidol and quinine both increase QTc interval. Use Caution/Monitor.

• ramelteon

  haloperidol and ramelteon both increase sedation. Use Caution/Monitor.

• ranolazine

  ranolazine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and ranolazine both increase QTc interval. Modify Therapy/Monitor Closely.

• rapacuronium

  rapacuronium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  rapacuronium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of rapacuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• remimazolam

  remimazolam, haloperidol. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely. Coadministration may result in profound sedation, respiratory depression, coma, and/or death. Continuously monitor vital signs during sedation and recovery period if coadministered. Carefully titrate remimazolam dose if administered with opioid analgesics and/or sedative/hypnotics.

• ribociclib

  ribociclib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• rifabutin

  rifabutin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• rifampin

  rifampin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• rifapentine

  rifapentine will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• rilpivirine

  rilpivirine increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Rilpivirine should be used with caution when co-administered with a drug with a known risk of Torsades de Pointes.

• rimabotulinumtoxinB

  haloperidol, rimabotulinumtoxinB. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Anticholinergics may enhance botulinum toxin effects. Closely monitor for increased neuromuscular blockade.

• rimegepant

  haloperidol will increase the level or effect of rimegepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid repeating rimegepant dose within 48 hr if coadministered with a moderate CYP3A4 inhibitor.

• risperidone

  haloperidol and risperidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and risperidone both increase QTc interval. Modify Therapy/Monitor Closely.
  
  haloperidol and risperidone both increase sedation. Use Caution/Monitor.

• ritonavir

  ritonavir will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and ritonavir both increase QTc interval. Use Caution/Monitor.
  
  ritonavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• rizatriptan

  rizatriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• rocuronium

  rocuronium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  rocuronium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of rocuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• rolapitant

  rolapitant will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Rolapitant may increase plasma concentrations of CYP2D6 substrates for at least 28 days following rolapitant administration.

• rucaparib

  rucaparib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.

• ruxolitinib

  haloperidol will increase the level or effect of ruxolitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ruxolitinib topical

  haloperidol will increase the level or effect of ruxolitinib topical by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• salmeterol

  haloperidol increases and salmeterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• scopolamine

  scopolamine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  scopolamine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of scopolamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• scullcap

  haloperidol and scullcap both increase sedation. Use Caution/Monitor.

• secobarbital

  secobarbital and haloperidol both increase sedation. Use Caution/Monitor.

• selegiline

  selegiline, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• selpercatinib

  selpercatinib increases toxicity of haloperidol by QTc interval. Use Caution/Monitor.

• sertraline

  sertraline will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and sertraline both increase QTc interval. Use Caution/Monitor.

• sevoflurane

  sevoflurane and haloperidol both increase sedation. Use Caution/Monitor.

• shepherd's purse

  haloperidol and shepherd's purse both increase sedation. Use Caution/Monitor.

• sodium sulfate/?magnesium sulfate/potassium chloride

  sodium sulfate/?magnesium sulfate/potassium chloride increases effects of haloperidol by unknown mechanism. Use Caution/Monitor. Closely monitor for evidence of enhanced CNS depression when using higher dose of magnesium sulfate together with a CNS depressant.

• sodium sulfate/potassium sulfate/magnesium sulfate

  sodium sulfate/potassium sulfate/magnesium sulfate increases effects of haloperidol by unknown mechanism. Use Caution/Monitor. Closely monitor for evidence of enhanced CNS depression when using higher dose of magnesium sulfate together with a CNS depressant.

• solifenacin

  solifenacin decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  solifenacin decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of solifenacin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
  
  haloperidol and solifenacin both increase QTc interval. Use Caution/Monitor.

• sonidegib

  haloperidol will increase the level or effect of sonidegib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid coadministration of sonidegib with moderate CYP3A4 inhibitors. If a moderate CYP3A inhibitor must be used, administer the moderate CYP3A inhibitor for <14 days and monitor closely for adverse reactions, particularly musculoskeletal adverse reactions.

• sorafenib

  sorafenib and haloperidol both increase QTc interval. Use Caution/Monitor.

• sparsentan

  haloperidol will increase the level or effect of sparsentan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No dosage adjustment needed. Monitor blood pressure, serum potassium, edema, and kidney function regularly if sparsentan is coadministered with moderate CYP3A4 inhibitors.

• stiripentol

  stiripentol, haloperidol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.
  
  stiripentol, haloperidol. Either increases effects of the other by sedation. Use Caution/Monitor. Concomitant use stiripentol with other CNS depressants, including alcohol, may increase the risk of sedation and somnolence.

• sufentanil

  sufentanil and haloperidol both increase sedation. Use Caution/Monitor.

• sufentanil SL

  haloperidol will increase the level or effect of sufentanil SL by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of sufentanil SL with any CYP3A4 inhibitor may increase sufentanil plasma concentration, and, thereby increase or prolonged adverse effects, including potentially fatal respiratory depression.

• sulfamethoxazole

  sulfamethoxazole and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• sumatriptan

  sumatriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• sumatriptan intranasal

  sumatriptan intranasal, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• sunitinib

  haloperidol and sunitinib both increase QTc interval. Use Caution/Monitor.

• suvorexant

  haloperidol will increase the level or effect of suvorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease suvorexant starting dose to 5 mg HS if coadministered with moderate CYP3A4 inhibitors

• tacrolimus

  haloperidol and tacrolimus both increase QTc interval. Use Caution/Monitor.

• tadalafil

  haloperidol will increase the level or effect of tadalafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may reduce tadalafil clearance increasing systemic exposure to tadalafil; increased levels may result in increased associated adverse events.

• tamoxifen

  haloperidol decreases effects of tamoxifen by decreasing metabolism. Use Caution/Monitor. Inhibition of CYP2D6 metabolism to tamoxifen's active metabolite, endoxifen.

• tamsulosin

  haloperidol increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.
  
  haloperidol increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• tapentadol

  tapentadol and haloperidol both increase sedation. Use Caution/Monitor.

• tazemetostat

  tazemetostat will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tecovirimat

  tecovirimat will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.

• teduglutide

  teduglutide increases levels of haloperidol by Other (see comment). Use Caution/Monitor. Comment: Teduglutide may increase absorption of concomitant PO medications; caution with with drugs requiring titration or those with a narrow therapeutic index; dose adjustment may be necessary.

• telavancin

  haloperidol and telavancin both increase QTc interval. Modify Therapy/Monitor Closely.

• temazepam

  temazepam and haloperidol both increase sedation. Use Caution/Monitor.

• terbinafine

  terbinafine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.

• terbutaline

  haloperidol increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• tetrabenazine

  haloperidol and tetrabenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely.

• tezacaftor

  haloperidol will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• thioridazine

  thioridazine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and thioridazine both increase sedation. Use Caution/Monitor.

• thiothixene

  haloperidol and thiothixene both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and thiothixene both increase sedation. Use Caution/Monitor.
  
  haloperidol and thiothixene both increase QTc interval. Use Caution/Monitor.

• timolol

  haloperidol will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• tinidazole

  haloperidol will increase the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tiotropium

  tiotropium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  tiotropium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of tiotropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• tipranavir

  tipranavir will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  tipranavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tofacitinib

  haloperidol increases levels of tofacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No specific dose adjustment recommended when tofacitinib coadministered with moderate CYP3A4 inhibitors; decrease tofacitinib dose if coadministered with both moderate CYP3A4 and potent CYP2C19 inhibitors.

• tolterodine

  tolterodine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  tolterodine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• topiramate

  haloperidol and topiramate both increase sedation. Modify Therapy/Monitor Closely.

• trabectedin

  haloperidol will increase the level or effect of trabectedin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tramadol

  tramadol and haloperidol both increase sedation. Use Caution/Monitor.

• tranylcypromine

  tranylcypromine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• trazodone

  haloperidol and trazodone both increase sedation. Use Caution/Monitor.

• triazolam

  triazolam and haloperidol both increase sedation. Use Caution/Monitor.

• triclabendazole

  triclabendazole and haloperidol both increase QTc interval. Use Caution/Monitor.

• triclofos

  triclofos and haloperidol both increase sedation. Use Caution/Monitor.

• trifluoperazine

  haloperidol and trifluoperazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and trifluoperazine both increase sedation. Use Caution/Monitor.

• trihexyphenidyl

  haloperidol increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

• trimethoprim

  haloperidol and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.

• trimipramine

  haloperidol and trimipramine both increase sedation. Use Caution/Monitor.

• triprolidine

  triprolidine and haloperidol both increase sedation. Use Caution/Monitor.

• triptorelin

  triptorelin increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Increases risk of torsades de pointes.

• tropisetron

  haloperidol and tropisetron both increase QTc interval. Modify Therapy/Monitor Closely.

• trospium chloride

  trospium chloride decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  trospium chloride decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of trospium chloride by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• valbenazine

  valbenazine and haloperidol both increase QTc interval. Use Caution/Monitor.

• vardenafil

  haloperidol and vardenafil both increase QTc interval. Use Caution/Monitor.
  
  haloperidol will increase the level or effect of vardenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Vardenafil dose may need to be reduced if coadministered with moderate or strong CYP3A4 inhibitors

• vecuronium

  vecuronium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  vecuronium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of vecuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• venlafaxine

  venlafaxine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and venlafaxine both increase QTc interval. Modify Therapy/Monitor Closely.
  
  venlafaxine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• vilazodone

  vilazodone, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• voclosporin

  haloperidol will increase the level or effect of voclosporin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce voclosporin daily dosage to 15.8 mg PO in AM and 7.9 mg PO in PM.
  
  voclosporin, haloperidol. Either increases effects of the other by QTc interval. Use Caution/Monitor.

• voriconazole

  haloperidol and voriconazole both increase QTc interval. Modify Therapy/Monitor Closely.
  
  voriconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• vorinostat

  haloperidol and vorinostat both increase QTc interval. Use Caution/Monitor.

• xylometazoline

  haloperidol increases and xylometazoline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• yohimbine

  haloperidol increases and yohimbine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• zanubrutinib

  haloperidol will increase the level or effect of zanubrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce zanubrutinib (a CYP3A4 substrate) to 80 mg PO BID to when coadministered with a moderate CYP3A4 inhibitor. Interrupt dose as recommended for adverse reactions. After discontinuing the CYP3A4 inhibitor, resume previous dose of zanubrutinib.

• ziconotide

  haloperidol and ziconotide both increase sedation. Use Caution/Monitor.

• ziprasidone

  haloperidol and ziprasidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and ziprasidone both increase sedation. Use Caution/Monitor.

• zolmitriptan

  zolmitriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• zotepine

  haloperidol and zotepine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and zotepine both increase sedation. Use Caution/Monitor.

Minor (44)

• acetazolamide

  acetazolamide will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• amobarbital

  haloperidol, amobarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• anastrozole

  anastrozole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• aripiprazole

  haloperidol will increase the level or effect of aripiprazole by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• brimonidine

  brimonidine increases effects of haloperidol by pharmacodynamic synergism. Minor/Significance Unknown. Increased CNS depression.

• butabarbital

  haloperidol, butabarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• butalbital

  haloperidol, butalbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• chasteberry

  chasteberry decreases effects of haloperidol by pharmacodynamic antagonism. Minor/Significance Unknown. (Theoretical interaction).

• chlorpromazine

  haloperidol will increase the level or effect of chlorpromazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• cyclophosphamide

  cyclophosphamide will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• dexfenfluramine

  haloperidol will increase the level or effect of dexfenfluramine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• dextroamphetamine

  haloperidol will increase the level or effect of dextroamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• dextromethorphan

  haloperidol will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• donepezil

  haloperidol will increase the level or effect of donepezil by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• duloxetine

  duloxetine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
  
  haloperidol will increase the level or effect of duloxetine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• encainide

  haloperidol will increase the level or effect of encainide by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• estradiol vaginal

  haloperidol will increase the level or effect of estradiol vaginal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• ethanol

  ethanol, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive CNS depression.

• eucalyptus

  haloperidol and eucalyptus both increase sedation. Minor/Significance Unknown.

• fesoterodine

  haloperidol will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• fluphenazine

  haloperidol will increase the level or effect of fluphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• galantamine

  haloperidol will increase the level or effect of galantamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• indomethacin

  indomethacin increases toxicity of haloperidol by unknown mechanism. Minor/Significance Unknown.

• irinotecan

  haloperidol will increase the level or effect of irinotecan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• irinotecan liposomal

  haloperidol will increase the level or effect of irinotecan liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• larotrectinib

  larotrectinib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• loratadine

  haloperidol will increase the level or effect of loratadine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• metyrosine

  metyrosine increases effects of haloperidol by pharmacodynamic synergism. Minor/Significance Unknown.

• oliceridine

  haloperidol will increase the level or effect of oliceridine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.

• oxycodone

  haloperidol decreases effects of oxycodone by decreasing metabolism. Minor/Significance Unknown. Decreased conversion of oxycodone to active metabolite morphine.

• pentobarbital

  haloperidol, pentobarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• perhexiline

  haloperidol will increase the level or effect of perhexiline by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• perphenazine

  haloperidol will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• phenobarbital

  haloperidol, phenobarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• primidone

  haloperidol, primidone. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• prochlorperazine

  haloperidol will increase the level or effect of prochlorperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• promazine

  haloperidol will increase the level or effect of promazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• promethazine

  haloperidol will increase the level or effect of promethazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• risperidone

  haloperidol will increase the level or effect of risperidone by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• sage

  haloperidol and sage both increase sedation. Minor/Significance Unknown.

• secobarbital

  haloperidol, secobarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• tolterodine

  haloperidol will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• trifluoperazine

  haloperidol will increase the level or effect of trifluoperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• tropisetron

  haloperidol will increase the level or effect of tropisetron by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• abametapir

  Serious - Use Alternative (1)abametapir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir.

• abiraterone

  Monitor Closely (1)abiraterone increases levels of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Avoid coadministration of abiraterone with substrates of CYP2D6. If alternative therapy cannot be used, exercise caution and consider a dose reduction of the CYP2D6 substrate.

• abobotulinumtoxinA

  Monitor Closely (1)abobotulinumtoxinA increases effects of haloperidol by pharmacodynamic synergism. Use Caution/Monitor. Use of anticholinergic drugs after administration of botulinum toxin-containing products may potentiate systemic anticholinergic effects.

• acalabrutinib

  Monitor Closely (2)acalabrutinib, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration may increase risk of myelosuppressive effects.
  
  haloperidol will increase the level or effect of acalabrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease acalabrutinib dose to 100 mg once daily if coadministered with a moderate CYP3A inhibitor.

• acetazolamide

  Minor (1)acetazolamide will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• aclidinium

  Monitor Closely (2)aclidinium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of aclidinium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• acrivastine

  Monitor Closely (1)acrivastine and haloperidol both increase sedation. Use Caution/Monitor.

• adagrasib

  Serious - Use Alternative (1)adagrasib, haloperidol. Either increases effects of the other by QTc interval. Avoid or Use Alternate Drug. Each drug prolongs the QTc interval, which may increased the risk of Torsade de pointes, other serious arryhthmias, and sudden death. If coadministration unavoidable, more frequent monitoring is recommended for such patients.

• albuterol

  Monitor Closely (2)albuterol and haloperidol both increase QTc interval. Use Caution/Monitor.
  
  haloperidol increases and albuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• alfentanil

  Monitor Closely (1)alfentanil and haloperidol both increase sedation. Use Caution/Monitor.

• alfuzosin

  Monitor Closely (2)alfuzosin and haloperidol both increase QTc interval. Use Caution/Monitor.
  
  haloperidol and alfuzosin both increase QTc interval. Use Caution/Monitor.

• almotriptan

  Monitor Closely (1)almotriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• alprazolam

  Monitor Closely (1)alprazolam and haloperidol both increase sedation. Use Caution/Monitor.

• amifampridine

  Monitor Closely (1)haloperidol increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.

• amiodarone

  Serious - Use Alternative (1)amiodarone and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• amisulpride

  Contraindicated (1)amisulpride, haloperidol. Either increases toxicity of the other by Other (see comment). Contraindicated. Comment: Increases risk of neuroleptic malignant syndrome.Serious - Use Alternative (1)amisulpride and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. ECG monitoring is recommended if coadministered.

• amitriptyline

  Monitor Closely (1)haloperidol and amitriptyline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)amitriptyline and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• amobarbital

  Monitor Closely (2)amobarbital and haloperidol both increase sedation. Use Caution/Monitor.
  
  amobarbital will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)haloperidol, amobarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• amoxapine

  Monitor Closely (2)haloperidol and amoxapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely.
  
  haloperidol and amoxapine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)amoxapine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• anagrelide

  Serious - Use Alternative (1)anagrelide and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• anastrozole

  Minor (1)anastrozole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• anticholinergic/sedative combos

  Monitor Closely (3)anticholinergic/sedative combos decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  anticholinergic/sedative combos decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of anticholinergic/sedative combos by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• apalutamide

  Serious - Use Alternative (1)apalutamide will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.

• apomorphine

  Monitor Closely (2)haloperidol and apomorphine both increase sedation. Use Caution/Monitor.
  
  haloperidol and apomorphine both increase QTc interval. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol decreases effects of apomorphine by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• arformoterol

  Monitor Closely (2)haloperidol increases and arformoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  haloperidol and arformoterol both increase QTc interval. Use Caution/Monitor.

• aripiprazole

  Monitor Closely (3)aripiprazole and haloperidol both increase QTc interval. Use Caution/Monitor.
  
  aripiprazole and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  aripiprazole and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol will increase the level or effect of aripiprazole by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• armodafinil

  Monitor Closely (1)haloperidol increases and armodafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• arsenic trioxide

  Serious - Use Alternative (1)arsenic trioxide and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• artemether

  Monitor Closely (1)haloperidol and artemether both increase QTc interval. Use Caution/Monitor.

• artemether/lumefantrine

  Serious - Use Alternative (2)haloperidol and artemether/lumefantrine both increase QTc interval. Avoid or Use Alternate Drug.
  
  artemether/lumefantrine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• asenapine

  Monitor Closely (3)asenapine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  asenapine and haloperidol both increase sedation. Use Caution/Monitor.
  
  haloperidol and asenapine both increase QTc interval. Use Caution/Monitor.

• asenapine transdermal

  Monitor Closely (2)asenapine transdermal and haloperidol both increase QTc interval. Use Caution/Monitor.
  
  asenapine transdermal and haloperidol both increase sedation. Use Caution/Monitor.

• atazanavir

  Monitor Closely (1)atazanavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• atogepant

  Monitor Closely (1)haloperidol will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• atomoxetine

  Monitor Closely (2)atomoxetine and haloperidol both increase QTc interval. Use Caution/Monitor.
  
  haloperidol will increase the level or effect of atomoxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• atracurium

  Monitor Closely (3)atracurium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  atracurium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of atracurium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• atropine

  Monitor Closely (3)atropine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  atropine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of atropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• atropine IV/IM

  Monitor Closely (3)haloperidol increases effects of atropine IV/IM by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
  
  atropine IV/IM decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  atropine IV/IM decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.

• avanafil

  Monitor Closely (1)haloperidol will increase the level or effect of avanafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may reduce avanafil clearance increasing systemic exposure to avanafil; increased levels may result in increased associated adverse events; the maximum recommended dose of STENDRA is 50 mg, not to exceed once every 24 hours for patients taking concomitant moderate CYP3A4 inhibitors

• avapritinib

  Monitor Closely (1)avapritinib and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol will increase the level or effect of avapritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of avapritinib with moderate CYP3A4 inhibitors. If unable to avoid, reduce avapritinib starting dose. See drug monograph Dosage Modifications.

• axitinib

  Serious - Use Alternative (1)haloperidol increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with moderate CYP3A4 inhibitors, monitor closely and reduce dose if necessary .

• azelastine

  Monitor Closely (1)azelastine and haloperidol both increase sedation. Use Caution/Monitor.

• azithromycin

  Monitor Closely (1)azithromycin and haloperidol both increase QTc interval. Use Caution/Monitor.

• baclofen

  Monitor Closely (1)baclofen and haloperidol both increase sedation. Use Caution/Monitor.

• bedaquiline

  Monitor Closely (1)haloperidol and bedaquiline both increase QTc interval. Modify Therapy/Monitor Closely. ECG should be monitored closely

• belladonna alkaloids

  Monitor Closely (3)belladonna alkaloids decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  belladonna alkaloids decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of belladonna alkaloids by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• belladonna and opium

  Monitor Closely (4)belladonna and opium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  belladonna and opium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of belladonna and opium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
  
  belladonna and opium and haloperidol both increase sedation. Use Caution/Monitor.

• belzutifan

  Monitor Closely (1)belzutifan will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If unable to avoid coadministration of belzutifan with sensitive CYP3A4 substrates, consider increasing the sensitive CYP3A4 substrate dose in accordance with its prescribing information.

• benperidol

  Monitor Closely (2)benperidol and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  benperidol and haloperidol both increase sedation. Use Caution/Monitor.

• benzhydrocodone/acetaminophen

  Monitor Closely (2)haloperidol will increase the level or effect of benzhydrocodone/acetaminophen by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone [benzhydrocodone is prodrug of hydrocodone]) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.
  
  benzhydrocodone/acetaminophen and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)benzhydrocodone/acetaminophen, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• benzphetamine

  Monitor Closely (1)haloperidol increases and benzphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• benztropine

  Monitor Closely (1)haloperidol increases effects of benztropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic adverse effects may be seen with concurrent use. .

• bosentan

  Monitor Closely (1)bosentan will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• bosutinib

  Monitor Closely (1)bosutinib and haloperidol both increase QTc interval. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol increases levels of bosutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• brexanolone

  Monitor Closely (1)brexanolone, haloperidol. Either increases toxicity of the other by sedation. Use Caution/Monitor.

• brexpiprazole

  Monitor Closely (3)brexpiprazole and haloperidol both increase sedation. Use Caution/Monitor.
  
  haloperidol will increase the level or effect of brexpiprazole by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP2D6 inhibitor PLUS a strong/moderate CYP3A4 inhibitor.
  
  haloperidol will increase the level or effect of brexpiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP3A4 inhibitor PLUS a strong/moderate CYP2D6 inhibitor.

• brimonidine

  Monitor Closely (1)brimonidine and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)brimonidine increases effects of haloperidol by pharmacodynamic synergism. Minor/Significance Unknown. Increased CNS depression.

• brivaracetam

  Monitor Closely (1)brivaracetam and haloperidol both increase sedation. Use Caution/Monitor.

• bromocriptine

  Serious - Use Alternative (1)haloperidol decreases effects of bromocriptine by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• brompheniramine

  Monitor Closely (1)brompheniramine and haloperidol both increase sedation. Use Caution/Monitor.

• buprenorphine

  Monitor Closely (1)buprenorphine and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)buprenorphine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• buprenorphine buccal

  Monitor Closely (1)buprenorphine buccal and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)buprenorphine buccal and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• buprenorphine subdermal implant

  Monitor Closely (2)buprenorphine subdermal implant and haloperidol both increase sedation. Use Caution/Monitor.
  
  haloperidol will increase the level or effect of buprenorphine subdermal implant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor patients already on buprenorphine subdermal implant who require newly-initiated treatment with CYP3A4 inhibitors for signs and symptoms of overmedication. If the dose of the concomitant CYP3A4 inhibitor cannot be reduced or discontinued, implant removal may be necessary and the patient should then be treated with a buprenorphine dosage form that permits dose adjustments. If a CYP3A4 inhibitor is discontinued in a patient who has been stabilized on buprenorphine, monitor the patient for withdrawal.Serious - Use Alternative (1)buprenorphine subdermal implant and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• buprenorphine transdermal

  Monitor Closely (1)buprenorphine transdermal and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)buprenorphine transdermal and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• buprenorphine, long-acting injection

  Monitor Closely (2)haloperidol will increase the level or effect of buprenorphine, long-acting injection by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Patients who transfer to buprenorphine long-acting injection from transmucosal buprenorphine coadministered with CYP3A4 inhibitors should be monitored to ensure buprenorphine plasma levels are adequate. Within 2 weeks, if signs and symptoms of buprenorphine toxicity or overdose occur and the concomitant CYP3A4 inhibitor cannot be reduced or discontinued, transition the patient back to a buprenorphine formulation that permits dose adjustments.
  
  haloperidol increases toxicity of buprenorphine, long-acting injection by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of buprenorphine and benzodiazepines or other CNS depressants increases risk of adverse reactions including overdose, respiratory depression, and death. Cessation of benzodiazepines or other CNS depressants is preferred in most cases. In some cases, monitoring at a higher level of care for tapering CNS depressants may be appropriate. In others, gradually tapering a patient off of a prescribed benzodiazepine or other CNS depressant or decreasing to the lowest effective dose may be appropriate.Serious - Use Alternative (1)buprenorphine, long-acting injection and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• bupropion

  Monitor Closely (1)bupropion will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• butabarbital

  Monitor Closely (1)butabarbital and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol, butabarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• butalbital

  Monitor Closely (1)butalbital and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol, butalbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• butorphanol

  Monitor Closely (1)butorphanol and haloperidol both increase sedation. Use Caution/Monitor.

• cabergoline

  Serious - Use Alternative (1)haloperidol decreases effects of cabergoline by pharmacodynamic antagonism. Contraindicated.

• cabozantinib

  Monitor Closely (1)haloperidol will increase the level or effect of cabozantinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• caffeine

  Monitor Closely (1)haloperidol increases and caffeine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• calcium/magnesium/potassium/sodium oxybates

  Serious - Use Alternative (1)haloperidol, calcium/magnesium/potassium/sodium oxybates. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• cannabidiol

  Monitor Closely (1)haloperidol will increase the level or effect of cannabidiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider reducing the cannabidiol dose when coadministered with a moderate CYP3A4 inhibitor.

• capecitabine

  Monitor Closely (1)capecitabine and haloperidol both increase QTc interval. Use Caution/Monitor.

• carbamazepine

  Monitor Closely (1)carbamazepine decreases levels of haloperidol by increasing metabolism. Use Caution/Monitor.Serious - Use Alternative (1)carbamazepine will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• carbinoxamine

  Monitor Closely (1)carbinoxamine and haloperidol both increase sedation. Use Caution/Monitor.

• carisoprodol

  Monitor Closely (1)carisoprodol and haloperidol both increase sedation. Use Caution/Monitor.

• carvedilol

  Monitor Closely (1)haloperidol will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• celecoxib

  Monitor Closely (1)celecoxib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• cenobamate

  Monitor Closely (1)cenobamate will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.

• ceritinib

  Serious - Use Alternative (2)ceritinib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.
  
  ceritinib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• chasteberry

  Minor (1)chasteberry decreases effects of haloperidol by pharmacodynamic antagonism. Minor/Significance Unknown. (Theoretical interaction).

• chloral hydrate

  Monitor Closely (1)chloral hydrate and haloperidol both increase sedation. Use Caution/Monitor.

• chloramphenicol

  Serious - Use Alternative (1)chloramphenicol will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• chlordiazepoxide

  Monitor Closely (1)chlordiazepoxide and haloperidol both increase sedation. Use Caution/Monitor.

• chloroquine

  Monitor Closely (2)chloroquine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  chloroquine increases toxicity of haloperidol by QTc interval. Use Caution/Monitor.

• chlorpheniramine

  Monitor Closely (1)chlorpheniramine and haloperidol both increase sedation. Use Caution/Monitor.

• chlorpromazine

  Monitor Closely (2)chlorpromazine and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  chlorpromazine and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)chlorpromazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of chlorpromazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• chlorzoxazone

  Monitor Closely (1)chlorzoxazone and haloperidol both increase sedation. Use Caution/Monitor.

• cimetidine

  Monitor Closely (1)cimetidine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• cinnarizine

  Monitor Closely (1)cinnarizine and haloperidol both increase sedation. Use Caution/Monitor.

• ciprofloxacin

  Monitor Closely (1)ciprofloxacin and haloperidol both increase QTc interval. Use Caution/Monitor. Ciprofloxacin elicits minimal effects on QT interval. Caution if used in combination with other drugs known to affect QT interval or in patients with other risk factors.

• cisatracurium

  Monitor Closely (3)cisatracurium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  cisatracurium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of cisatracurium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• citalopram

  Serious - Use Alternative (2)citalopram will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Increased risk of serotonin syndrome or neuroleptic malignant syndrome. Potential risk for QT prolongation. ECG monitoring is recommended.
  
  citalopram and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• clarithromycin

  Serious - Use Alternative (2)clarithromycin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.
  
  clarithromycin will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• clemastine

  Monitor Closely (1)clemastine and haloperidol both increase sedation. Use Caution/Monitor.

• clobazam

  Monitor Closely (1)clobazam will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Lower doses of drugs metabolized by CYP2D6 may be required when used concomitantly.

• clomipramine

  Monitor Closely (1)haloperidol and clomipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)clomipramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.
  
  haloperidol will increase the level or effect of clomipramine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• clonazepam

  Monitor Closely (1)clonazepam and haloperidol both increase sedation. Use Caution/Monitor.

• clonidine

  Monitor Closely (2)clonidine, haloperidol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
  
  clonidine increases toxicity of haloperidol by Other (see comment). Use Caution/Monitor. Comment: High doses of clonidine IV may increase arrhythmogenic potential (QT-prolongation, ventricular fibrillation) of high dose haloperidol IV in patients experiencing alcoholic delirium.

• clorazepate

  Monitor Closely (1)clorazepate and haloperidol both increase sedation. Use Caution/Monitor.

• clozapine

  Monitor Closely (3)clozapine and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  clozapine and haloperidol both increase sedation. Use Caution/Monitor.
  
  haloperidol and clozapine both increase QTc interval. Use Caution/Monitor.

• cobicistat

  Monitor Closely (1)cobicistat will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• cobimetinib

  Serious - Use Alternative (1)haloperidol will increase the level or effect of cobimetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If concurrent short term (14 days or less) use of moderate CYP3A inhibitors is unavoidable for patients who are taking cobimetinib 60 mg, reduce the cobimetinib dose to 20 mg. After discontinuation of a moderate CYP3A inhibitor, resume cobimetinib 60 mg. Use an alternative to a moderate CYP3A inhibitor in patients who are taking a reduced dose of cobimetinib (40 or 20 mg daily).

• codeine

  Monitor Closely (2)haloperidol decreases effects of codeine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Prevents conversion of codeine to its active metabolite morphine.
  
  codeine and haloperidol both increase sedation. Use Caution/Monitor.

• conivaptan

  Monitor Closely (1)conivaptan will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• crizotinib

  Monitor Closely (1)crizotinib increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A. ECG monitoring is recommended, along with drugs that may prolong the QT interval.Serious - Use Alternative (1)crizotinib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• crofelemer

  Monitor Closely (1)crofelemer increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.

• cyclizine

  Monitor Closely (4)cyclizine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  cyclizine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of cyclizine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
  
  cyclizine and haloperidol both increase sedation. Use Caution/Monitor.

• cyclobenzaprine

  Monitor Closely (4)cyclobenzaprine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  cyclobenzaprine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of cyclobenzaprine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
  
  cyclobenzaprine and haloperidol both increase sedation. Use Caution/Monitor.

• cyclophosphamide

  Minor (1)cyclophosphamide will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• cyproheptadine

  Monitor Closely (1)cyproheptadine and haloperidol both increase sedation. Use Caution/Monitor.

• dabrafenib

  Monitor Closely (2)dabrafenib and haloperidol both increase QTc interval. Use Caution/Monitor.
  
  dabrafenib will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• dacomitinib

  Serious - Use Alternative (1)dacomitinib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid use with CYP2D6 substrates where minimal increases in concentration of the CYP2D6 substrate may lead to serious or life-threatening toxicities.

• dantrolene

  Monitor Closely (1)dantrolene and haloperidol both increase sedation. Use Caution/Monitor.

• daridorexant

  Monitor Closely (2)haloperidol will increase the level or effect of daridorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Daridorexant dose should not exceed 25 mg per night when coadministered with moderate CYP3A4 inhibitors.
  
  haloperidol and daridorexant both increase sedation. Modify Therapy/Monitor Closely. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.

• darifenacin

  Monitor Closely (4)darifenacin will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  darifenacin decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  darifenacin decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of darifenacin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• darunavir

  Monitor Closely (1)darunavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• dasatinib

  Monitor Closely (1)dasatinib and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• deferasirox

  Monitor Closely (1)deferasirox will increase the level or effect of haloperidol by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• deflazacort

  Monitor Closely (1)haloperidol will increase the level or effect of deflazacort by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease deflazacort dose to one-third of the recommended dose if coadministered with moderate or strong CYP3A4 inhibitors.

• degarelix

  Monitor Closely (1)haloperidol and degarelix both increase QTc interval. Use Caution/Monitor.

• desflurane

  Monitor Closely (1)desflurane and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)desflurane and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• desipramine

  Monitor Closely (1)haloperidol and desipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)desipramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.
  
  haloperidol will increase the level or effect of desipramine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• desvenlafaxine

  Monitor Closely (1)desvenlafaxine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Desvenlafaxine inhibits CYP2D6; with higher desvenlafaxine doses (ie, 400 mg) decrease the CYP2D6 substrate dose by up to 50%; no dosage adjustment needed with desvenlafaxine doses <100 mg

• deutetrabenazine

  Monitor Closely (3)haloperidol and deutetrabenazine both increase sedation. Use Caution/Monitor.
  
  haloperidol and deutetrabenazine both increase QTc interval. Use Caution/Monitor. At the maximum recommended dose, deutetrabenazine does not prolong QT interval to a clinically relevant extent. Certain circumstances may increase risk of torsade de pointes and/or sudden death in association with drugs that prolong the QTc interval (eg, bradycardia, hypokalemia or hypomagnesemia, coadministration with other drugs that prolong QTc interval, presence of congenital QT prolongation).
  
  haloperidol and deutetrabenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely. The risk for parkinsonism, neuroleptic malignant syndrome, and akathisia may be increased by concomitant use of deutetrabenazine and dopamine antagonists or antipsychotics.

• dexchlorpheniramine

  Monitor Closely (1)dexchlorpheniramine and haloperidol both increase sedation. Use Caution/Monitor.

• dexfenfluramine

  Monitor Closely (1)haloperidol increases and dexfenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)haloperidol will increase the level or effect of dexfenfluramine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• dexmedetomidine

  Monitor Closely (1)dexmedetomidine and haloperidol both increase sedation. Use Caution/Monitor.

• dexmethylphenidate

  Monitor Closely (1)haloperidol increases and dexmethylphenidate decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dextroamphetamine

  Monitor Closely (1)haloperidol increases and dextroamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)haloperidol will increase the level or effect of dextroamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• dextromethorphan

  Monitor Closely (1)dextromethorphan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).Minor (1)haloperidol will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• dextromoramide

  Monitor Closely (1)dextromoramide and haloperidol both increase sedation. Use Caution/Monitor.

• diamorphine

  Monitor Closely (1)diamorphine and haloperidol both increase sedation. Use Caution/Monitor.

• diazepam

  Monitor Closely (1)diazepam and haloperidol both increase sedation. Use Caution/Monitor.

• diazepam intranasal

  Monitor Closely (1)haloperidol will increase the level or effect of diazepam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong or moderate CYP3A4 inhibitors may decrease rate of diazepam elimination, thereby increasing adverse reactions to diazepam.

• dicyclomine

  Monitor Closely (3)dicyclomine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  dicyclomine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of dicyclomine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• diethylpropion

  Monitor Closely (1)haloperidol increases and diethylpropion decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• difelikefalin

  Monitor Closely (1)difelikefalin and haloperidol both increase sedation. Use Caution/Monitor.

• difenoxin hcl

  Monitor Closely (1)difenoxin hcl and haloperidol both increase sedation. Use Caution/Monitor.

• dihydroergotamine

  Monitor Closely (1)dihydroergotamine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• dimenhydrinate

  Monitor Closely (1)dimenhydrinate and haloperidol both increase sedation. Use Caution/Monitor.

• diphenhydramine

  Monitor Closely (5)diphenhydramine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  diphenhydramine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  diphenhydramine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
  
  diphenhydramine and haloperidol both increase sedation. Use Caution/Monitor.

• diphenoxylate hcl

  Monitor Closely (1)diphenoxylate hcl and haloperidol both increase sedation. Use Caution/Monitor.

• dipipanone

  Monitor Closely (1)dipipanone and haloperidol both increase sedation. Use Caution/Monitor.

• disopyramide

  Contraindicated (1)disopyramide and haloperidol both increase QTc interval. Contraindicated.

• dobutamine

  Monitor Closely (1)haloperidol increases and dobutamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dofetilide

  Serious - Use Alternative (1)dofetilide and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• dolasetron

  Monitor Closely (1)dolasetron and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• donepezil

  Monitor Closely (1)donepezil and haloperidol both increase QTc interval. Use Caution/Monitor.Minor (1)haloperidol will increase the level or effect of donepezil by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• donepezil transdermal

  Monitor Closely (1)donepezil transdermal, haloperidol. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.

• dopamine

  Monitor Closely (1)haloperidol increases and dopamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol decreases effects of dopamine by pharmacodynamic antagonism. Contraindicated.

• dopexamine

  Monitor Closely (1)haloperidol increases and dopexamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dosulepin

  Monitor Closely (1)haloperidol and dosulepin both increase sedation. Use Caution/Monitor.

• doxepin

  Monitor Closely (1)haloperidol and doxepin both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)doxepin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.
  
  haloperidol will increase the level or effect of doxepin by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• doxylamine

  Monitor Closely (1)doxylamine and haloperidol both increase sedation. Use Caution/Monitor.

• dronedarone

  Monitor Closely (1)dronedarone will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)dronedarone and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• droperidol

  Monitor Closely (2)droperidol and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  droperidol and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)droperidol and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• duloxetine

  Minor (2)duloxetine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
  
  haloperidol will increase the level or effect of duloxetine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• duvelisib

  Monitor Closely (1)duvelisib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with duvelisib increases AUC of a sensitive CYP3A4 substrate which may increase the risk of toxicities of these drugs. Consider reducing the dose of the sensitive CYP3A4 substrate and monitor for signs of toxicities of the coadministered sensitive CYP3A substrate.

• efavirenz

  Monitor Closely (2)efavirenz will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  efavirenz and haloperidol both increase QTc interval. Use Caution/Monitor.

• elacestrant

  Serious - Use Alternative (1)haloperidol will increase the level or effect of elacestrant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• elagolix

  Monitor Closely (1)elagolix decreases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.

• eletriptan

  Monitor Closely (1)eletriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• eliglustat

  Contraindicated (1)haloperidol increases levels of eliglustat by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. If coadministered with strong or moderate CYP2D6 inhibitors, reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive and intermediate metabolizers; eliglustat is contraindiated if strong or moderate CYP2D6 inhibitors are given concomitantly with strong or moderate CYP3A inhibitors.Monitor Closely (1)eliglustat increases levels of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the concomitant drug and titrate to clinical effect.Serious - Use Alternative (2)haloperidol increases levels of eliglustat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Moderate CYP3A4 inhibitors are not recommended with eliglustat poor or intermediate metabolizers; reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive metabolizers .
  
  eliglustat and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  Monitor Closely (2)elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.
  
  elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP2D6 inhibitor; caution with CYP2D6 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

• encainide

  Minor (1)haloperidol will increase the level or effect of encainide by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• encorafenib

  Monitor Closely (1)encorafenib, haloperidol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.Serious - Use Alternative (1)encorafenib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• entrectinib

  Serious - Use Alternative (2)haloperidol and entrectinib both increase QTc interval. Avoid or Use Alternate Drug.
  
  haloperidol will increase the level or effect of entrectinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of moderate CYP3A4 inhibitors with entrectinib, a CYP3A4 substrate. If coadministration unavoidable, reduce dose to 200 mg/day for patients aged 12 y or older with BSA >1.50m2. Resume previous entrectinib dose after discontinuing moderate CYP3A inhibitor for 3-5 elimination half-lives.

• enzalutamide

  Monitor Closely (1)enzalutamide will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ephedrine

  Monitor Closely (1)haloperidol increases and ephedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• epinephrine

  Monitor Closely (1)haloperidol increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)epinephrine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• epinephrine racemic

  Monitor Closely (1)haloperidol increases and epinephrine racemic decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)epinephrine racemic and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• ergoloid mesylates

  Monitor Closely (1)ergoloid mesylates, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• ergotamine

  Monitor Closely (1)ergotamine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• eribulin

  Serious - Use Alternative (1)eribulin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Potential for enhanced QTc-prolonging effects; if concurrent use is necessary then ECG monitoring is recommended.

• erythromycin base

  Serious - Use Alternative (1)erythromycin base and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• erythromycin ethylsuccinate

  Serious - Use Alternative (1)erythromycin ethylsuccinate and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• erythromycin lactobionate

  Serious - Use Alternative (1)erythromycin lactobionate and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• erythromycin stearate

  Serious - Use Alternative (1)erythromycin stearate and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• escitalopram

  Monitor Closely (2)escitalopram increases toxicity of haloperidol by QTc interval. Use Caution/Monitor.
  
  haloperidol and escitalopram both increase QTc interval. Use Caution/Monitor.

• esketamine intranasal

  Monitor Closely (1)esketamine intranasal, haloperidol. Either increases toxicity of the other by sedation. Use Caution/Monitor.

• estazolam

  Monitor Closely (1)estazolam and haloperidol both increase sedation. Use Caution/Monitor.

• estradiol vaginal

  Minor (1)haloperidol will increase the level or effect of estradiol vaginal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• ethanol

  Monitor Closely (1)haloperidol and ethanol both increase sedation. Use Caution/Monitor.Minor (1)ethanol, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive CNS depression.

• etomidate

  Monitor Closely (1)etomidate and haloperidol both increase sedation. Use Caution/Monitor.

• etravirine

  Monitor Closely (1)etravirine will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• eucalyptus

  Minor (1)haloperidol and eucalyptus both increase sedation. Minor/Significance Unknown.

• ezogabine

  Monitor Closely (1)ezogabine, haloperidol. Either increases toxicity of the other by QTc interval. Use Caution/Monitor. Slight and transient QT-prolongation observed with ezogabine, particularly when dose titrated to 1200 mg/day. QT interval should be monitored when ezogabine is prescribed with agents known to increase QT interval.

• fedratinib

  Monitor Closely (2)fedratinib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.
  
  fedratinib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.

• fenfluramine

  Monitor Closely (1)haloperidol increases and fenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• fentanyl

  Monitor Closely (1)fentanyl, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).Serious - Use Alternative (2)fentanyl, haloperidol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.
  
  haloperidol will increase the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl intranasal

  Serious - Use Alternative (2)fentanyl intranasal, haloperidol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.
  
  haloperidol will increase the level or effect of fentanyl intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transdermal

  Serious - Use Alternative (2)fentanyl transdermal, haloperidol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.
  
  haloperidol will increase the level or effect of fentanyl transdermal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transmucosal

  Serious - Use Alternative (2)fentanyl transmucosal, haloperidol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.
  
  haloperidol will increase the level or effect of fentanyl transmucosal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fesoterodine

  Monitor Closely (3)fesoterodine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  fesoterodine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.Minor (1)haloperidol will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• fexinidazole

  Serious - Use Alternative (2)fexinidazole and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Avoid coadministration of fexinidazole with drugs known to block potassium channels or prolong QT interval.
  
  fexinidazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

• finerenone

  Monitor Closely (1)haloperidol will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor serum potassium during initiation and dosage adjustment of either finererone or moderate CYP3A4 inhibitors. Adjust finererone dosage as needed.

• fingolimod

  Serious - Use Alternative (1)fingolimod and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• flavoxate

  Monitor Closely (3)flavoxate decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  flavoxate decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of flavoxate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• flecainide

  Monitor Closely (2)haloperidol will increase the level or effect of flecainide by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised.
  
  flecainide and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• flibanserin

  Contraindicated (1)haloperidol will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of flibanserin with moderate or strong CYP3A4 inhibitors is contraindicated. Severe hypotension or syncope can occur.Monitor Closely (1)flibanserin, haloperidol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• fluconazole

  Serious - Use Alternative (1)fluconazole and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• fluoxetine

  Monitor Closely (1)fluoxetine and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.Serious - Use Alternative (2)fluoxetine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  haloperidol will increase the level or effect of fluoxetine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• fluphenazine

  Monitor Closely (2)fluphenazine and haloperidol both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  fluphenazine and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)fluphenazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of fluphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• flurazepam

  Monitor Closely (1)flurazepam and haloperidol both increase sedation. Use Caution/Monitor.

• fluvoxamine

  Monitor Closely (1)fluvoxamine and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• formoterol

  Monitor Closely (1)haloperidol increases and formoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)formoterol and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• foscarnet

  Monitor Closely (1)foscarnet and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• fosphenytoin

  Serious - Use Alternative (1)fosphenytoin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• fostemsavir

  Monitor Closely (1)haloperidol and fostemsavir both increase QTc interval. Use Caution/Monitor. QTc prolongation reported with higher than recommended doses of fostemsavir.

• frovatriptan

  Monitor Closely (1)frovatriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• gadobenate

  Monitor Closely (1)gadobenate and haloperidol both increase QTc interval. Use Caution/Monitor.

• galantamine

  Minor (1)haloperidol will increase the level or effect of galantamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• ganaxolone

  Monitor Closely (1)haloperidol and ganaxolone both increase sedation. Use Caution/Monitor.

• gemifloxacin

  Monitor Closely (1)haloperidol and gemifloxacin both increase QTc interval. Use Caution/Monitor.

• gemtuzumab

  Monitor Closely (1)haloperidol and gemtuzumab both increase QTc interval. Use Caution/Monitor.

• gilteritinib

  Monitor Closely (1)gilteritinib and haloperidol both increase QTc interval. Use Caution/Monitor.

• givosiran

  Serious - Use Alternative (1)givosiran will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling.

• glasdegib

  Serious - Use Alternative (1)haloperidol and glasdegib both increase QTc interval. Avoid or Use Alternate Drug. If coadministration unavoidable, monitor for increased risk of QTc interval prolongation.

• glycerol phenylbutyrate

  Monitor Closely (1)haloperidol decreases effects of glycerol phenylbutyrate by Other (see comment). Use Caution/Monitor. Comment: Haloperidol may induce hyperammonemia; monitor ammonia levels closely when coadministered with glycerol phenylbutyrate.

• glycopyrrolate

  Monitor Closely (1)haloperidol increases effects of glycopyrrolate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• glycopyrrolate inhaled

  Monitor Closely (3)glycopyrrolate inhaled decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  glycopyrrolate inhaled decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of glycopyrrolate inhaled by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• glycopyrronium tosylate topical

  Monitor Closely (1)glycopyrronium tosylate topical, haloperidol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration of glycopyrronium tosylate topical with other anticholinergic medications may result in additive anticholinergic adverse effects.

• goserelin

  Monitor Closely (1)goserelin increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Increases risk of torsades de pointes.

• granisetron

  Monitor Closely (1)granisetron and haloperidol both increase QTc interval. Use Caution/Monitor.

• guanfacine

  Monitor Closely (2)guanfacine, haloperidol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
  
  haloperidol will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.

• henbane

  Monitor Closely (3)henbane decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  henbane decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of henbane by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• histrelin

  Monitor Closely (1)histrelin increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Increases risk of torsades de pointes.

• homatropine

  Monitor Closely (3)homatropine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  homatropine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of homatropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• hydrocodone

  Monitor Closely (1)haloperidol will increase the level or effect of hydrocodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.Serious - Use Alternative (1)hydrocodone, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• hydromorphone

  Monitor Closely (2)haloperidol will increase the level or effect of hydromorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  hydromorphone and haloperidol both increase sedation. Use Caution/Monitor.

• hydroxychloroquine sulfate

  Serious - Use Alternative (1)hydroxychloroquine sulfate and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• hydroxyzine

  Monitor Closely (2)hydroxyzine and haloperidol both increase QTc interval. Use Caution/Monitor.
  
  hydroxyzine and haloperidol both increase sedation. Use Caution/Monitor.

• hyoscyamine

  Monitor Closely (3)hyoscyamine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  hyoscyamine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• hyoscyamine spray

  Monitor Closely (3)haloperidol increases effects of hyoscyamine spray by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
  
  hyoscyamine spray decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  hyoscyamine spray decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.

• ibrutinib

  Monitor Closely (1)haloperidol increases levels of ibrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate CYP3A4 inhibitors, reduce ibrutinib dose to 280 mg qDay (B-cell malignancies) or 420 mg qDay (graft versus host disease). After CYP3A inhibitor discontinuation, resume previous dose of ibrutinib.

• ibutilide

  Contraindicated (1)haloperidol and ibutilide both increase QTc interval. Contraindicated.

• idelalisib

  Serious - Use Alternative (1)idelalisib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates

• ifosfamide

  Monitor Closely (1)haloperidol decreases effects of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• iloperidone

  Monitor Closely (5)haloperidol will increase the level or effect of iloperidone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and iloperidone both increase QTc interval. Modify Therapy/Monitor Closely.
  
  haloperidol and iloperidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and iloperidone both increase sedation. Use Caution/Monitor.
  
  iloperidone increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.

• imatinib

  Monitor Closely (1)imatinib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• imipramine

  Monitor Closely (1)haloperidol and imipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)imipramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.
  
  haloperidol will increase the level or effect of imipramine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• incobotulinumtoxinA

  Monitor Closely (1)haloperidol, incobotulinumtoxinA. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Use of anticholinergic drugs after administration of botulinum toxin-containing products may potentiate systemic anticholinergic effects.

• indacaterol, inhaled

  Monitor Closely (1)indacaterol, inhaled, haloperidol. QTc interval. Use Caution/Monitor. Drugs that are known to prolong the QTc interval may have an increased the risk of ventricular arrhythmias.

• indapamide

  Contraindicated (1)haloperidol and indapamide both increase QTc interval. Contraindicated.

• indinavir

  Serious - Use Alternative (1)indinavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• indomethacin

  Minor (1)indomethacin increases toxicity of haloperidol by unknown mechanism. Minor/Significance Unknown.

• infigratinib

  Serious - Use Alternative (1)haloperidol will increase the level or effect of infigratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• inotuzumab

  Serious - Use Alternative (1)inotuzumab and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. If unable to avoid concomitant use, obtain ECGs and electrolytes before and after initiation of any drug known to prolong QTc, and periodically monitor as clinically indicated during treatment.

• ipratropium

  Monitor Closely (3)ipratropium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  ipratropium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of ipratropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• irinotecan

  Minor (1)haloperidol will increase the level or effect of irinotecan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• irinotecan liposomal

  Minor (1)haloperidol will increase the level or effect of irinotecan liposomal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• isavuconazonium sulfate

  Monitor Closely (1)haloperidol will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• isoflurane

  Serious - Use Alternative (1)isoflurane and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• isoniazid

  Monitor Closely (1)isoniazid will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• isoproterenol

  Monitor Closely (1)haloperidol increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• isradipine

  Monitor Closely (1)haloperidol and isradipine both increase QTc interval. Use Caution/Monitor.

• istradefylline

  Monitor Closely (1)istradefylline will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.

• itraconazole

  Monitor Closely (2)itraconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  haloperidol and itraconazole both increase QTc interval. Modify Therapy/Monitor Closely.

• ivabradine

  Serious - Use Alternative (1)haloperidol will increase the level or effect of ivabradine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of ivabradine with moderate CYP3A4 inhibitors.

• ivacaftor

  Monitor Closely (1)haloperidol will increase the level or effect of ivacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce ivacaftor dose if coadministered with moderate CYP3A4 inhibitors. See specific ivacaftor-containing product for precise dosage modification.

• ivosidenib

  Monitor Closely (1)haloperidol will increase the level or effect of ivosidenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration with moderate CYP3A4 inhibitors may increase ivosidenib plasma concentrations, thus increasing the risk of QTc prolongation. Monitor for increased risk of QTc interval prolongation.Serious - Use Alternative (2)ivosidenib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Avoid coadministration of QTc prolonging drugs with ivosidenib or replace with alternate therapies. If coadministration of a QTc prolonging drug is unavoidable, monitor for increased risk of QTc interval prolongation.
  
  ivosidenib will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternate therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.

• ketamine

  Monitor Closely (1)ketamine and haloperidol both increase sedation. Use Caution/Monitor.

• ketoconazole

  Monitor Closely (1)ketoconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol and ketoconazole both increase QTc interval. Avoid or Use Alternate Drug.

• ketotifen, ophthalmic

  Monitor Closely (1)haloperidol and ketotifen, ophthalmic both increase sedation. Use Caution/Monitor.

• lapatinib

  Monitor Closely (1)haloperidol and lapatinib both increase QTc interval. Modify Therapy/Monitor Closely.

• larotrectinib

  Minor (1)larotrectinib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• lasmiditan

  Monitor Closely (1)lasmiditan, haloperidol. Either increases effects of the other by sedation. Use Caution/Monitor. Coadministration of lasmiditan and other CNS depressant drugs, including alcohol have not been evaluated in clinical studies. Lasmiditan may cause sedation, as well as other cognitive and/or neuropsychiatric adverse reactions.

• lefamulin

  Contraindicated (1)lefamulin will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Lefamulin is contraindicated with CYP3A substrates know to prolong the QT interval.

• lemborexant

  Monitor Closely (1)lemborexant, haloperidol. Either increases effects of the other by sedation. Modify Therapy/Monitor Closely. Dosage adjustment may be necessary if lemborexant is coadministered with other CNS depressants because of potentially additive effects.Serious - Use Alternative (1)haloperidol will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of lemborexant with moderate or strong CYP3A inhibitors.

• lenacapavir

  Monitor Closely (1)lenacapavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.

• lenvatinib

  Monitor Closely (1)haloperidol and lenvatinib both increase QTc interval. Use Caution/Monitor. Lenvatinib prescribing information recommends monitoring ECG closely when coadministered with QT prolonging drugs.

• letermovir

  Monitor Closely (1)letermovir increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• leuprolide

  Monitor Closely (1)leuprolide increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Increases risk of torsades de pointes.

• levalbuterol

  Monitor Closely (1)haloperidol increases and levalbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• levamlodipine

  Monitor Closely (1)haloperidol will increase the level or effect of levamlodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate and strong CYP3A inhibitors results in increased systemic exposure to amlodipine and may require dose reduction. Monitor for symptoms of hypotension and edema when amlodipine is coadministered with CYP3A inhibitors to determine the need for dose adjustment.

• levodopa

  Serious - Use Alternative (1)haloperidol decreases effects of levodopa by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• levofloxacin

  Monitor Closely (1)haloperidol and levofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.

• levoketoconazole

  Monitor Closely (1)levoketoconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol and levoketoconazole both increase QTc interval. Avoid or Use Alternate Drug.

• levomilnacipran

  Monitor Closely (1)levomilnacipran, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• levorphanol

  Monitor Closely (1)levorphanol and haloperidol both increase sedation. Use Caution/Monitor.

• linezolid

  Monitor Closely (1)linezolid, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• lisdexamfetamine

  Monitor Closely (1)haloperidol increases and lisdexamfetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• lisuride

  Serious - Use Alternative (1)haloperidol decreases effects of lisuride by pharmacodynamic antagonism. Contraindicated.

• lithium

  Monitor Closely (3)lithium, haloperidol. Other (see comment). Use Caution/Monitor. Comment: Risk of neurotoxicity. Multiple mechanisms involved.
  
  lithium, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  lithium and haloperidol both increase QTc interval. Use Caution/Monitor.

• lofepramine

  Monitor Closely (2)haloperidol will increase the level or effect of lofepramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and lofepramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)lofepramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• lofexidine

  Monitor Closely (1)haloperidol and lofexidine both increase sedation. Use Caution/Monitor.

• lomitapide

  Contraindicated (1)haloperidol increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Increases lomitapide levels several folds.

• lonafarnib

  Contraindicated (1)haloperidol will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Lonafarnib is a sensitive CYP3A4 substrate. Coadministration with strong or moderate CYP3A4 inhibitors is contraindicated.

• lopinavir

  Serious - Use Alternative (1)lopinavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• loprazolam

  Monitor Closely (1)loprazolam and haloperidol both increase sedation. Use Caution/Monitor.

• loratadine

  Minor (1)haloperidol will increase the level or effect of loratadine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• lorazepam

  Monitor Closely (1)lorazepam and haloperidol both increase sedation. Use Caution/Monitor.

• lorcaserin

  Monitor Closely (2)lorcaserin will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  lorcaserin, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• lorlatinib

  Monitor Closely (1)lorlatinib will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• lormetazepam

  Monitor Closely (1)lormetazepam and haloperidol both increase sedation. Use Caution/Monitor.

• loxapine

  Monitor Closely (2)haloperidol and loxapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and loxapine both increase sedation. Use Caution/Monitor.

• loxapine inhaled

  Monitor Closely (2)haloperidol and loxapine inhaled both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and loxapine inhaled both increase sedation. Use Caution/Monitor.

• lumateperone

  Monitor Closely (1)haloperidol will increase the level or effect of lumateperone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce lumateperone dose to 21 mg/day if coadministered with moderate CYP3A4 inhibitors.

• lumefantrine

  Serious - Use Alternative (2)haloperidol and lumefantrine both increase QTc interval. Avoid or Use Alternate Drug.
  
  lumefantrine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• lurasidone

  Monitor Closely (1)lurasidone, haloperidol. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Potential for increased CNS depressant effects when used concurrently; monitor for increased adverse effects and toxicity.

• lurbinectedin

  Serious - Use Alternative (1)haloperidol will increase the level or effect of lurbinectedin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• macimorelin

  Serious - Use Alternative (1)macimorelin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Macimorelin causes an increase of ~11 msec in the corrected QT interval. Avoid coadministration with drugs that prolong QT interval, which could increase risk for developing torsade de pointes-type ventricular tachycardia. Allow sufficient washout time of drugs that are known to prolong the QT interval before administering macimorelin.

• maprotiline

  Monitor Closely (1)haloperidol and maprotiline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)maprotiline and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• maraviroc

  Monitor Closely (1)maraviroc will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• marijuana

  Monitor Closely (2)marijuana will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and marijuana both increase sedation. Use Caution/Monitor.

• mavacamten

  Monitor Closely (1)haloperidol will increase the level or effect of mavacamten by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Inititiation of moderate CYP3A4 inhibitors may require decreased mavacamten dose.

• meclizine

  Monitor Closely (3)meclizine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  meclizine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of meclizine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• mefloquine

  Monitor Closely (2)haloperidol will increase the level or effect of mefloquine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  haloperidol and mefloquine both increase QTc interval. Use Caution/Monitor.

• melatonin

  Monitor Closely (1)haloperidol and melatonin both increase sedation. Use Caution/Monitor.

• meperidine

  Monitor Closely (2)meperidine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  meperidine and haloperidol both increase sedation. Use Caution/Monitor.

• meprobamate

  Monitor Closely (1)haloperidol and meprobamate both increase sedation. Use Caution/Monitor.

• metaproterenol

  Monitor Closely (1)haloperidol increases and metaproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• metaxalone

  Monitor Closely (1)metaxalone and haloperidol both increase sedation. Use Caution/Monitor.

• methadone

  Monitor Closely (3)methadone, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  haloperidol and methadone both increase QTc interval. Modify Therapy/Monitor Closely.
  
  methadone and haloperidol both increase sedation. Use Caution/Monitor.

• methamphetamine

  Monitor Closely (2)haloperidol will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• methocarbamol

  Monitor Closely (1)methocarbamol and haloperidol both increase sedation. Use Caution/Monitor.

• methscopolamine

  Monitor Closely (3)methscopolamine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  methscopolamine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of methscopolamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• methyldopa

  Serious - Use Alternative (1)haloperidol decreases effects of methyldopa by pharmacodynamic antagonism. Contraindicated.

• methylenedioxymethamphetamine

  Monitor Closely (1)haloperidol increases and methylenedioxymethamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• methylergonovine

  Monitor Closely (1)methylergonovine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• methylphenidate

  Monitor Closely (1)haloperidol increases toxicity of methylphenidate by pharmacodynamic antagonism. Use Caution/Monitor. Closely monitor for signs of altered clinical response to either methylphenidate or an antipsychotic when using these drugs in combination.

• metoclopramide

  Monitor Closely (1)haloperidol and metoclopramide both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.

• metoclopramide intranasal

  Serious - Use Alternative (2)haloperidol, metoclopramide intranasal. Either increases effects of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid use of metoclopramide intranasal or interacting drug, depending on importance of drug to patient.
  
  haloperidol increases toxicity of metoclopramide intranasal by pharmacodynamic synergism. Avoid or Use Alternate Drug. Potential for additive effects, including increased frequency and severity of tardive dyskinesia, other extrapyramidal symptoms, and neuroleptic malignant syndrome.

• metoprolol

  Monitor Closely (1)haloperidol will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• metyrosine

  Minor (1)metyrosine increases effects of haloperidol by pharmacodynamic synergism. Minor/Significance Unknown.

• mexiletine

  Monitor Closely (2)haloperidol will increase the level or effect of mexiletine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised
  
  haloperidol and mexiletine both increase QTc interval. Use Caution/Monitor.

• midazolam

  Monitor Closely (1)midazolam and haloperidol both increase sedation. Use Caution/Monitor.

• midazolam intranasal

  Monitor Closely (1)midazolam intranasal, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase the risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.Serious - Use Alternative (1)haloperidol will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of moderate CYP3A4 inhibitors with midazolam intranasal causes higher midazolam systemic exposure, which may prolong sedation.

• midodrine

  Monitor Closely (1)haloperidol increases and midodrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• mifepristone

  Monitor Closely (1)mifepristone, haloperidol. QTc interval. Modify Therapy/Monitor Closely. Use alternatives if available.Serious - Use Alternative (1)mifepristone will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• milnacipran

  Monitor Closely (1)milnacipran, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• mirabegron

  Monitor Closely (1)mirabegron will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• mirtazapine

  Monitor Closely (2)mirtazapine and haloperidol both increase QTc interval. Use Caution/Monitor.
  
  haloperidol and mirtazapine both increase sedation. Use Caution/Monitor.

• mitotane

  Monitor Closely (1)mitotane decreases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.

• mobocertinib

  Serious - Use Alternative (2)haloperidol will increase the level or effect of mobocertinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If use of moderate CYP3A4 inhibitor unavoidable, reduce mobocertinib dose by ~50% (eg, 160 to 80 mg); closely monitor QTc interval.
  
  mobocertinib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. If coadministration unavoidable, reduce mobocertinib dose and monitor QTc interval more frequently.

• modafinil

  Monitor Closely (1)haloperidol increases and modafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• morphine

  Monitor Closely (2)haloperidol will increase the level or effect of morphine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  morphine and haloperidol both increase sedation. Use Caution/Monitor.

• motherwort

  Monitor Closely (1)haloperidol and motherwort both increase sedation. Use Caution/Monitor.

• moxifloxacin

  Serious - Use Alternative (1)haloperidol and moxifloxacin both increase QTc interval. Avoid or Use Alternate Drug.

• moxonidine

  Monitor Closely (1)haloperidol and moxonidine both increase sedation. Use Caution/Monitor.

• nabilone

  Monitor Closely (1)haloperidol and nabilone both increase sedation. Use Caution/Monitor.

• nafcillin

  Monitor Closely (1)nafcillin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• nalbuphine

  Monitor Closely (1)nalbuphine and haloperidol both increase sedation. Use Caution/Monitor.

• naldemedine

  Monitor Closely (1)haloperidol increases levels of naldemedine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor naldemedine for potential adverse effects if coadministered with strong or moderate CYP3A4 inhibitors.

• naloxegol

  Serious - Use Alternative (1)haloperidol will increase the level or effect of naloxegol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministation of naloxegol with moderate CYP3A4 inhibitors is unavoidable, reduce naloxegol dose to 12.5 mg qDay

• naratriptan

  Monitor Closely (1)naratriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• nebivolol

  Monitor Closely (1)haloperidol will increase the level or effect of nebivolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• nefazodone

  Monitor Closely (1)nefazodone will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• nelfinavir

  Monitor Closely (1)nelfinavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• neratinib

  Serious - Use Alternative (1)haloperidol will increase the level or effect of neratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of neratinib with strong/moderate CYP3A4 inhibitors.

• nilotinib

  Monitor Closely (1)nilotinib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol and nilotinib both increase QTc interval. Avoid or Use Alternate Drug.

• norepinephrine

  Monitor Closely (1)haloperidol increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• nortriptyline

  Monitor Closely (1)haloperidol and nortriptyline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)nortriptyline and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.
  
  haloperidol will increase the level or effect of nortriptyline by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• octreotide

  Serious - Use Alternative (1)haloperidol and octreotide both increase QTc interval. Avoid or Use Alternate Drug.

• octreotide (Antidote)

  Serious - Use Alternative (1)haloperidol and octreotide (Antidote) both increase QTc interval. Avoid or Use Alternate Drug.

• ofloxacin

  Monitor Closely (1)haloperidol and ofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.

• olanzapine

  Monitor Closely (3)haloperidol and olanzapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and olanzapine both increase sedation. Use Caution/Monitor.
  
  haloperidol and olanzapine both increase QTc interval. Use Caution/Monitor.

• olaparib

  Serious - Use Alternative (1)haloperidol will increase the level or effect of olaparib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with moderate CYP3A inhibitors cannot be avoided, reduce olaparib dose to 200 mg (capsule) or 150 mg (tablet) PO BID. Do not substitute tablets with capsules.

• oliceridine

  Monitor Closely (2)haloperidol will increase the level or effect of oliceridine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.
  
  oliceridine, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.Minor (1)haloperidol will increase the level or effect of oliceridine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.

• olodaterol inhaled

  Monitor Closely (1)haloperidol and olodaterol inhaled both increase QTc interval. Use Caution/Monitor. Drugs that prolong the QTc interval and may potentiate the effects of beta2 agonists on the cardiovascular system; increased risk of ventricular arrhythmias

• olopatadine intranasal

  Serious - Use Alternative (1)haloperidol and olopatadine intranasal both increase sedation. Avoid or Use Alternate Drug. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.

• omaveloxolone

  Serious - Use Alternative (1)haloperidol will increase the level or effect of omaveloxolone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unavoidable, reduce omaveloxolone dose to 100 mg/day. Closely monitor for adverse effects. If adverse effects emerge, further reduce to 50 mg/day.

• onabotulinumtoxinA

  Monitor Closely (3)onabotulinumtoxinA decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  onabotulinumtoxinA decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of onabotulinumtoxinA by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• ondansetron

  Serious - Use Alternative (1)haloperidol and ondansetron both increase QTc interval. Avoid or Use Alternate Drug. Avoid with congenital long QT syndrome; ECG monitoring recommended with concomitant medications that prolong QT interval, electrolyte abnormalities, CHF, or bradyarrhythmias.

• opium tincture

  Monitor Closely (1)opium tincture and haloperidol both increase sedation. Use Caution/Monitor.

• orphenadrine

  Monitor Closely (1)orphenadrine and haloperidol both increase sedation. Use Caution/Monitor.

• osilodrostat

  Monitor Closely (1)osilodrostat and haloperidol both increase QTc interval. Use Caution/Monitor.

• osimertinib

  Monitor Closely (1)osimertinib and haloperidol both increase QTc interval. Use Caution/Monitor. Conduct periodic monitoring with ECGs and electrolytes in patients taking drugs known to prolong the QTc interval.

• oxaliplatin

  Monitor Closely (1)oxaliplatin will increase the level or effect of haloperidol by Other (see comment). Use Caution/Monitor. Monitor for ECG changes if therapy is initiated in patients with drugs known to prolong QT interval.Serious - Use Alternative (1)oxaliplatin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• oxazepam

  Monitor Closely (1)oxazepam and haloperidol both increase sedation. Use Caution/Monitor.

• oxybutynin

  Monitor Closely (3)oxybutynin decreases effects of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  oxybutynin decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  haloperidol increases effects of oxybutynin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• oxybutynin topical

  Monitor Closely (3)oxybutynin topical decreases effects of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  oxybutynin topical decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  haloperidol increases effects of oxybutynin topical by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• oxybutynin transdermal

  Monitor Closely (3)oxybutynin transdermal decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  oxybutynin transdermal decreases effects of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of oxybutynin transdermal by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• oxycodone

  Monitor Closely (2)haloperidol will increase the level or effect of oxycodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  oxycodone and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol decreases effects of oxycodone by decreasing metabolism. Minor/Significance Unknown. Decreased conversion of oxycodone to active metabolite morphine.

• oxymorphone

  Monitor Closely (2)haloperidol will increase the level or effect of oxymorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  oxymorphone and haloperidol both increase sedation. Use Caution/Monitor.

• ozanimod

  Monitor Closely (1)ozanimod and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely. The potential additive effects on heart rate, treatment with ozanimod should generally not be initiated in patients who are concurrently treated with QT prolonging drugs with known arrhythmogenic properties.

• pacritinib

  Serious - Use Alternative (1)haloperidol will increase the level or effect of pacritinib by affecting hepatic enzyme CYP2E1 metabolism. Avoid or Use Alternate Drug.

• palbociclib

  Monitor Closely (1)haloperidol will increase the level or effect of palbociclib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• paliperidone

  Monitor Closely (3)haloperidol and paliperidone both increase QTc interval. Modify Therapy/Monitor Closely.
  
  haloperidol and paliperidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and paliperidone both increase sedation. Use Caution/Monitor.

• pancuronium

  Monitor Closely (3)pancuronium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  pancuronium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of pancuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• panobinostat

  Serious - Use Alternative (1)haloperidol and panobinostat both increase QTc interval. Avoid or Use Alternate Drug. Panobinostat is known to significantly prolong QT interval. Panobinostat prescribing information states use with drugs known to prolong QTc is not recommended.

• papaveretum

  Monitor Closely (1)papaveretum and haloperidol both increase sedation. Use Caution/Monitor.

• papaverine

  Monitor Closely (1)haloperidol and papaverine both increase sedation. Use Caution/Monitor.

• parecoxib

  Monitor Closely (1)parecoxib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• paroxetine

  Monitor Closely (3)paroxetine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  haloperidol and paroxetine both increase QTc interval. Modify Therapy/Monitor Closely.
  
  haloperidol will increase the level or effect of paroxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)paroxetine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• pasireotide

  Monitor Closely (1)haloperidol and pasireotide both increase QTc interval. Modify Therapy/Monitor Closely.

• pazopanib

  Monitor Closely (1)haloperidol and pazopanib both increase QTc interval. Use Caution/Monitor.

• peginterferon alfa 2b

  Monitor Closely (1)peginterferon alfa 2b, haloperidol. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.

• pemigatinib

  Serious - Use Alternative (1)haloperidol will increase the level or effect of pemigatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pemigatinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pemigatinib dose.

• pentamidine

  Contraindicated (1)haloperidol and pentamidine both increase QTc interval. Contraindicated.

• pentazocine

  Monitor Closely (1)pentazocine and haloperidol both increase sedation. Use Caution/Monitor.

• pentobarbital

  Monitor Closely (1)pentobarbital and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol, pentobarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• perhexiline

  Minor (1)haloperidol will increase the level or effect of perhexiline by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• perphenazine

  Monitor Closely (3)perphenazine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and perphenazine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)perphenazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• pexidartinib

  Serious - Use Alternative (1)haloperidol will increase the level or effect of pexidartinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pexidartinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pexidartinib dose.

• phendimetrazine

  Monitor Closely (1)haloperidol increases and phendimetrazine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenelzine

  Monitor Closely (1)phenelzine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• phenobarbital

  Monitor Closely (2)phenobarbital will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  phenobarbital and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol, phenobarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• phentermine

  Monitor Closely (1)haloperidol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenylephrine

  Monitor Closely (1)haloperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenylephrine PO

  Monitor Closely (1)haloperidol increases and phenylephrine PO decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. .

• phenytoin

  Serious - Use Alternative (1)phenytoin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• pholcodine

  Monitor Closely (1)haloperidol and pholcodine both increase sedation. Use Caution/Monitor.

• pimozide

  Contraindicated (1)haloperidol and pimozide both increase QTc interval. Contraindicated.Monitor Closely (2)haloperidol and pimozide both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and pimozide both increase sedation. Use Caution/Monitor.

• pirbuterol

  Monitor Closely (1)haloperidol increases and pirbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• pitolisant

  Serious - Use Alternative (1)haloperidol and pitolisant both increase QTc interval. Avoid or Use Alternate Drug.

• posaconazole

  Monitor Closely (1)haloperidol and posaconazole both increase QTc interval. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)posaconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

• pralidoxime

  Monitor Closely (3)pralidoxime decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  pralidoxime decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of pralidoxime by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• pramipexole

  Serious - Use Alternative (1)haloperidol decreases effects of pramipexole by pharmacodynamic antagonism. Contraindicated.

• primaquine

  Monitor Closely (1)primaquine and haloperidol both increase QTc interval. Use Caution/Monitor.

• primidone

  Monitor Closely (2)primidone will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  primidone and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol, primidone. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• procainamide

  Contraindicated (1)haloperidol and procainamide both increase QTc interval. Contraindicated.

• procarbazine

  Monitor Closely (1)procarbazine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• prochlorperazine

  Monitor Closely (2)haloperidol and prochlorperazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and prochlorperazine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)prochlorperazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of prochlorperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• promazine

  Serious - Use Alternative (1)promazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of promazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• promethazine

  Monitor Closely (3)promethazine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  haloperidol and promethazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  promethazine and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)promethazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of promethazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• propafenone

  Monitor Closely (2)haloperidol will increase the level or effect of propafenone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised.
  
  haloperidol and propafenone both increase QTc interval. Use Caution/Monitor.

• propantheline

  Monitor Closely (3)propantheline decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  propantheline decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of propantheline by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• propofol

  Monitor Closely (1)propofol and haloperidol both increase sedation. Use Caution/Monitor.

• propranolol

  Monitor Closely (1)haloperidol will increase the level or effect of propranolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised. Coadministration of beta-blockers and haloperidol may cause an unexpected severe hypotensive reaction.

• propylhexedrine

  Monitor Closely (1)haloperidol increases and propylhexedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• protriptyline

  Monitor Closely (1)haloperidol and protriptyline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)protriptyline and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• quazepam

  Monitor Closely (1)quazepam and haloperidol both increase sedation. Use Caution/Monitor.

• quetiapine

  Monitor Closely (3)haloperidol and quetiapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and quetiapine both increase sedation. Use Caution/Monitor.
  
  quetiapine, haloperidol. Either increases toxicity of the other by QTc interval. Use Caution/Monitor. Avoid use with drugs that prolong QT and in patients with risk factors for prolonged QT interval. Postmarketing cases show QT prolongation with overdose in patients with concomitant illness or with drugs known to cause electrolyte imbalance or prolong QT.

• quinacrine

  Monitor Closely (1)quinacrine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• quinidine

  Contraindicated (1)quinidine and haloperidol both increase QTc interval. Contraindicated.Serious - Use Alternative (1)quinidine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• quinine

  Monitor Closely (1)haloperidol and quinine both increase QTc interval. Use Caution/Monitor.

• quinupristin/dalfopristin

  Serious - Use Alternative (1)quinupristin/dalfopristin increases levels of haloperidol by decreasing metabolism. Contraindicated. Risk of prolonged QTc interval.

• ramelteon

  Monitor Closely (1)haloperidol and ramelteon both increase sedation. Use Caution/Monitor.

• ranolazine

  Monitor Closely (2)ranolazine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and ranolazine both increase QTc interval. Modify Therapy/Monitor Closely.

• rapacuronium

  Monitor Closely (3)rapacuronium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  rapacuronium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of rapacuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• remimazolam

  Monitor Closely (1)remimazolam, haloperidol. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely. Coadministration may result in profound sedation, respiratory depression, coma, and/or death. Continuously monitor vital signs during sedation and recovery period if coadministered. Carefully titrate remimazolam dose if administered with opioid analgesics and/or sedative/hypnotics.

• ribociclib

  Monitor Closely (1)ribociclib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)ribociclib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• rifabutin

  Monitor Closely (1)rifabutin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• rifampin

  Monitor Closely (1)rifampin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• rifapentine

  Monitor Closely (1)rifapentine will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• rilpivirine

  Monitor Closely (1)rilpivirine increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Rilpivirine should be used with caution when co-administered with a drug with a known risk of Torsades de Pointes.

• rimabotulinumtoxinB

  Monitor Closely (1)haloperidol, rimabotulinumtoxinB. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Anticholinergics may enhance botulinum toxin effects. Closely monitor for increased neuromuscular blockade.

• rimegepant

  Monitor Closely (1)haloperidol will increase the level or effect of rimegepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid repeating rimegepant dose within 48 hr if coadministered with a moderate CYP3A4 inhibitor.

• risperidone

  Monitor Closely (3)haloperidol and risperidone both increase QTc interval. Modify Therapy/Monitor Closely.
  
  haloperidol and risperidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and risperidone both increase sedation. Use Caution/Monitor.Minor (1)haloperidol will increase the level or effect of risperidone by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• ritonavir

  Monitor Closely (3)ritonavir will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  ritonavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  haloperidol and ritonavir both increase QTc interval. Use Caution/Monitor.

• rizatriptan

  Monitor Closely (1)rizatriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• rocuronium

  Monitor Closely (3)rocuronium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  rocuronium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of rocuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• rolapitant

  Monitor Closely (1)rolapitant will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Rolapitant may increase plasma concentrations of CYP2D6 substrates for at least 28 days following rolapitant administration.

• romidepsin

  Serious - Use Alternative (1)haloperidol and romidepsin both increase QTc interval. Avoid or Use Alternate Drug.

• ropeginterferon alfa 2b

  Serious - Use Alternative (1)ropeginterferon alfa 2b, haloperidol. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Myelosuppressive agents can produce additive myelosuppression. Avoid use and monitor patients receiving the combination for effects of excessive myelosuppression.

• ropinirole

  Serious - Use Alternative (1)haloperidol decreases effects of ropinirole by pharmacodynamic antagonism. Contraindicated.

• rucaparib

  Monitor Closely (1)rucaparib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.

• ruxolitinib

  Monitor Closely (1)haloperidol will increase the level or effect of ruxolitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ruxolitinib topical

  Monitor Closely (1)haloperidol will increase the level or effect of ruxolitinib topical by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• safinamide

  Serious - Use Alternative (1)haloperidol decreases effects of safinamide by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Dopamine antagonists may decrease safinamide effects and exacerbate Parkinson disease symptoms.

• sage

  Minor (1)haloperidol and sage both increase sedation. Minor/Significance Unknown.

• salmeterol

  Monitor Closely (1)haloperidol increases and salmeterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• saquinavir

  Serious - Use Alternative (2)saquinavir increases levels of haloperidol by QTc interval. Avoid or Use Alternate Drug. Potential for increased toxicity. Increased risk of QT prolongation and cardiac arrhythmias.
  
  saquinavir increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Potential for increased toxicity. Increased risk of QT prolongation and cardiac arrhythmias.

• scopolamine

  Monitor Closely (3)scopolamine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  scopolamine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of scopolamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• scullcap

  Monitor Closely (1)haloperidol and scullcap both increase sedation. Use Caution/Monitor.

• secobarbital

  Monitor Closely (1)secobarbital and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol, secobarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.

• selegiline

  Monitor Closely (1)selegiline, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• selinexor

  Serious - Use Alternative (1)selinexor, haloperidol. unspecified interaction mechanism. Avoid or Use Alternate Drug. Patients treated with selinexor may experience neurological toxicities. Avoid taking selinexor with other medications that may cause dizziness or confusion.

• selpercatinib

  Monitor Closely (1)selpercatinib increases toxicity of haloperidol by QTc interval. Use Caution/Monitor.

• selumetinib

  Serious - Use Alternative (1)haloperidol will increase the level or effect of selumetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors cannot be avoided, reduce selumetinib dosage (refer to selumetinib monograph for further information). After discontinuation of the strong or moderate CYP3A4 inhibitor for 3 elimination half-lives, resume selumetinib dose that was taken before initiating the inhibitor.

• sertraline

  Monitor Closely (2)sertraline will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and sertraline both increase QTc interval. Use Caution/Monitor.

• sevoflurane

  Monitor Closely (1)sevoflurane and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)sevoflurane and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• shepherd's purse

  Monitor Closely (1)haloperidol and shepherd's purse both increase sedation. Use Caution/Monitor.

• siponimod

  Serious - Use Alternative (2)haloperidol will increase the level or effect of siponimod by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of siponimod with a moderate or strong CYP3A4 inhibitor PLUS a moderate or strong CYP2C9 inhibitor is not recommended.
  
  siponimod and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• sodium oxybate

  Serious - Use Alternative (1)haloperidol, sodium oxybate. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• sodium sulfate/?magnesium sulfate/potassium chloride

  Monitor Closely (1)sodium sulfate/?magnesium sulfate/potassium chloride increases effects of haloperidol by unknown mechanism. Use Caution/Monitor. Closely monitor for evidence of enhanced CNS depression when using higher dose of magnesium sulfate together with a CNS depressant.

• sodium sulfate/potassium sulfate/magnesium sulfate

  Monitor Closely (1)sodium sulfate/potassium sulfate/magnesium sulfate increases effects of haloperidol by unknown mechanism. Use Caution/Monitor. Closely monitor for evidence of enhanced CNS depression when using higher dose of magnesium sulfate together with a CNS depressant.

• solifenacin

  Monitor Closely (4)solifenacin decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  solifenacin decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of solifenacin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
  
  haloperidol and solifenacin both increase QTc interval. Use Caution/Monitor.

• sonidegib

  Monitor Closely (1)haloperidol will increase the level or effect of sonidegib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid coadministration of sonidegib with moderate CYP3A4 inhibitors. If a moderate CYP3A inhibitor must be used, administer the moderate CYP3A inhibitor for <14 days and monitor closely for adverse reactions, particularly musculoskeletal adverse reactions.

• sorafenib

  Monitor Closely (1)sorafenib and haloperidol both increase QTc interval. Use Caution/Monitor.

• sotalol

  Contraindicated (1)haloperidol and sotalol both increase QTc interval. Contraindicated.

• sparsentan

  Monitor Closely (1)haloperidol will increase the level or effect of sparsentan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No dosage adjustment needed. Monitor blood pressure, serum potassium, edema, and kidney function regularly if sparsentan is coadministered with moderate CYP3A4 inhibitors.

• stiripentol

  Monitor Closely (2)stiripentol, haloperidol. Either increases effects of the other by sedation. Use Caution/Monitor. Concomitant use stiripentol with other CNS depressants, including alcohol, may increase the risk of sedation and somnolence.
  
  stiripentol, haloperidol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.

• sufentanil

  Monitor Closely (1)sufentanil and haloperidol both increase sedation. Use Caution/Monitor.

• sufentanil SL

  Monitor Closely (1)haloperidol will increase the level or effect of sufentanil SL by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of sufentanil SL with any CYP3A4 inhibitor may increase sufentanil plasma concentration, and, thereby increase or prolonged adverse effects, including potentially fatal respiratory depression.Serious - Use Alternative (1)sufentanil SL, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration may result in hypotension, profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• sulfamethoxazole

  Monitor Closely (1)sulfamethoxazole and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely.

• sumatriptan

  Monitor Closely (1)sumatriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• sumatriptan intranasal

  Monitor Closely (1)sumatriptan intranasal, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• sunitinib

  Monitor Closely (1)haloperidol and sunitinib both increase QTc interval. Use Caution/Monitor.

• suvorexant

  Monitor Closely (1)haloperidol will increase the level or effect of suvorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease suvorexant starting dose to 5 mg HS if coadministered with moderate CYP3A4 inhibitors

• tacrolimus

  Monitor Closely (1)haloperidol and tacrolimus both increase QTc interval. Use Caution/Monitor.

• tadalafil

  Monitor Closely (1)haloperidol will increase the level or effect of tadalafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may reduce tadalafil clearance increasing systemic exposure to tadalafil; increased levels may result in increased associated adverse events.

• tamoxifen

  Monitor Closely (1)haloperidol decreases effects of tamoxifen by decreasing metabolism. Use Caution/Monitor. Inhibition of CYP2D6 metabolism to tamoxifen's active metabolite, endoxifen.

• tamsulosin

  Monitor Closely (2)haloperidol increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.
  
  haloperidol increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• tapentadol

  Monitor Closely (1)tapentadol and haloperidol both increase sedation. Use Caution/Monitor.

• tazemetostat

  Monitor Closely (1)tazemetostat will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of tazemetostat with moderate CYP3A4 inhibitors. If coadministration is unavoidable, reduce tazemetostat current dose (see drug monograph Dosage Modifications).

• tecovirimat

  Monitor Closely (1)tecovirimat will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.

• teduglutide

  Monitor Closely (1)teduglutide increases levels of haloperidol by Other (see comment). Use Caution/Monitor. Comment: Teduglutide may increase absorption of concomitant PO medications; caution with with drugs requiring titration or those with a narrow therapeutic index; dose adjustment may be necessary.

• telavancin

  Monitor Closely (1)haloperidol and telavancin both increase QTc interval. Modify Therapy/Monitor Closely.

• temazepam

  Monitor Closely (1)temazepam and haloperidol both increase sedation. Use Caution/Monitor.

• terbinafine

  Monitor Closely (1)terbinafine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.

• terbutaline

  Monitor Closely (1)haloperidol increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• tetrabenazine

  Monitor Closely (1)haloperidol and tetrabenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)tetrabenazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• tezacaftor

  Monitor Closely (1)haloperidol will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• thioridazine

  Monitor Closely (3)thioridazine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  haloperidol and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and thioridazine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)thioridazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.
  
  haloperidol will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• thiothixene

  Monitor Closely (3)haloperidol and thiothixene both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and thiothixene both increase sedation. Use Caution/Monitor.
  
  haloperidol and thiothixene both increase QTc interval. Use Caution/Monitor.

• timolol

  Monitor Closely (1)haloperidol will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• tinidazole

  Monitor Closely (1)haloperidol will increase the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tiotropium

  Monitor Closely (3)tiotropium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  tiotropium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of tiotropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• tipranavir

  Monitor Closely (2)tipranavir will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  tipranavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tofacitinib

  Monitor Closely (1)haloperidol increases levels of tofacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No specific dose adjustment recommended when tofacitinib coadministered with moderate CYP3A4 inhibitors; decrease tofacitinib dose if coadministered with both moderate CYP3A4 and potent CYP2C19 inhibitors.

• tolterodine

  Monitor Closely (3)tolterodine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  tolterodine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.Minor (1)haloperidol will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• topiramate

  Monitor Closely (1)haloperidol and topiramate both increase sedation. Modify Therapy/Monitor Closely.

• toremifene

  Serious - Use Alternative (1)haloperidol and toremifene both increase QTc interval. Avoid or Use Alternate Drug. Concurrent use of toremifene with agents causing QT prolongation should be avoided. If concomitant use is required it's recommended that toremifene be interrupted. If interruption not possible, patients requiring therapy with a drug that prolongs QT should be closely monitored. ECGs should be obtained for high risk patients.

• trabectedin

  Monitor Closely (1)haloperidol will increase the level or effect of trabectedin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tramadol

  Monitor Closely (1)tramadol and haloperidol both increase sedation. Use Caution/Monitor.

• tranylcypromine

  Monitor Closely (1)tranylcypromine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• trazodone

  Monitor Closely (1)haloperidol and trazodone both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)trazodone and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• triazolam

  Monitor Closely (1)triazolam and haloperidol both increase sedation. Use Caution/Monitor.

• triclabendazole

  Monitor Closely (1)triclabendazole and haloperidol both increase QTc interval. Use Caution/Monitor.

• triclofos

  Monitor Closely (1)triclofos and haloperidol both increase sedation. Use Caution/Monitor.

• trifluoperazine

  Monitor Closely (2)haloperidol and trifluoperazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and trifluoperazine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)trifluoperazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of trifluoperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• trihexyphenidyl

  Monitor Closely (1)haloperidol increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

• trimethoprim

  Monitor Closely (1)haloperidol and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.

• trimipramine

  Monitor Closely (1)haloperidol and trimipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)trimipramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.

• triprolidine

  Monitor Closely (1)triprolidine and haloperidol both increase sedation. Use Caution/Monitor.

• triptorelin

  Monitor Closely (1)triptorelin increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Increases risk of torsades de pointes.

• tropisetron

  Monitor Closely (1)haloperidol and tropisetron both increase QTc interval. Modify Therapy/Monitor Closely.Minor (1)haloperidol will increase the level or effect of tropisetron by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• trospium chloride

  Monitor Closely (3)trospium chloride decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  trospium chloride decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of trospium chloride by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• tucatinib

  Serious - Use Alternative (1)tucatinib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.

• umeclidinium bromide/vilanterol inhaled

  Serious - Use Alternative (1)haloperidol increases toxicity of umeclidinium bromide/vilanterol inhaled by QTc interval. Avoid or Use Alternate Drug. Exercise extreme caution when vilanterol coadministered with drugs that prolong QTc interval; adrenergic agonist effects on the cardiovascular system may be potentiated.

• valbenazine

  Monitor Closely (1)valbenazine and haloperidol both increase QTc interval. Use Caution/Monitor.

• vandetanib

  Serious - Use Alternative (1)haloperidol, vandetanib. Either increases toxicity of the other by QTc interval. Avoid or Use Alternate Drug. Avoid coadministration with drugs known to prolong QT interval; if a drug known to prolong QT interval must be used, more frequent ECG monitoring is recommended.

• vardenafil

  Monitor Closely (2)haloperidol will increase the level or effect of vardenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Vardenafil dose may need to be reduced if coadministered with moderate or strong CYP3A4 inhibitors
  
  haloperidol and vardenafil both increase QTc interval. Use Caution/Monitor.

• vecuronium

  Monitor Closely (3)vecuronium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
  
  vecuronium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.
  
  haloperidol increases effects of vecuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• vemurafenib

  Serious - Use Alternative (1)vemurafenib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Concomitant use of vemurafenib with drugs that prolong QT interval is not recommended.

• venetoclax

  Serious - Use Alternative (1)haloperidol will increase the level or effect of venetoclax by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If a moderate CYP3A inhibitor must be used, reduce the venetoclax dose by at least 50%. Monitor more closely for signs of venetoclax toxicities.

• venlafaxine

  Monitor Closely (3)venlafaxine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
  
  venlafaxine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  haloperidol and venlafaxine both increase QTc interval. Modify Therapy/Monitor Closely.

• vilanterol/fluticasone furoate inhaled

  Serious - Use Alternative (1)haloperidol increases toxicity of vilanterol/fluticasone furoate inhaled by QTc interval. Avoid or Use Alternate Drug. Exercise extreme caution when vilanterol coadministered with drugs that prolong QTc interval; adrenergic agonist effects on the cardiovascular system may be potentiated.

• vilazodone

  Monitor Closely (1)vilazodone, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• voclosporin

  Monitor Closely (2)voclosporin, haloperidol. Either increases effects of the other by QTc interval. Use Caution/Monitor.
  
  haloperidol will increase the level or effect of voclosporin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce voclosporin daily dosage to 15.8 mg PO in AM and 7.9 mg PO in PM.

• voriconazole

  Monitor Closely (2)voriconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  haloperidol and voriconazole both increase QTc interval. Modify Therapy/Monitor Closely.

• vorinostat

  Monitor Closely (1)haloperidol and vorinostat both increase QTc interval. Use Caution/Monitor.

• voxelotor

  Serious - Use Alternative (1)voxelotor will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.

• xylometazoline

  Monitor Closely (1)haloperidol increases and xylometazoline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• yohimbine

  Monitor Closely (1)haloperidol increases and yohimbine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• zanubrutinib

  Monitor Closely (1)haloperidol will increase the level or effect of zanubrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce zanubrutinib (a CYP3A4 substrate) to 80 mg PO BID to when coadministered with a moderate CYP3A4 inhibitor. Interrupt dose as recommended for adverse reactions. After discontinuing the CYP3A4 inhibitor, resume previous dose of zanubrutinib.

• ziconotide

  Monitor Closely (1)haloperidol and ziconotide both increase sedation. Use Caution/Monitor.

• ziprasidone

  Monitor Closely (2)haloperidol and ziprasidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and ziprasidone both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol and ziprasidone both increase QTc interval. Avoid or Use Alternate Drug.

• zolmitriptan

  Monitor Closely (1)zolmitriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• zotepine

  Monitor Closely (2)haloperidol and zotepine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
  
  haloperidol and zotepine both increase sedation. Use Caution/Monitor.