Dosing & Uses
Dosage Forms & Strengths
tablet
- 10mg
- 25mg
- 50mg
- 100mg
Schizophrenia
Initial 50-100 mg PO q8hr, THEN
200-800 mg/day PO divided q6-12hr
Depressive Disorders
25 mg PO q8hr; may titrate to effect (20-200 mg/day)
Renal Impairment
Dose adjustment not necessary in dialysis
Hepatic Disease
Initiate treatment at lower dose and titrate to effect (monitor)
Other Indications & Uses
Psychotic disorders, geriatric psychoneurotic manifestations, pediatric behavioral disorders
Dosage Forms & Strengths
tablet
- 10mg
- 25mg
- 50mg
- 100mg
Schizophrenia
<2 years: Safety and efficacy not established
2-12 years: 0.5-3 mg/kg/day divided q8hr PO, no more than 3 mg/kg/day
>12 years: Initial 50-100 mg PO q8hr; titrate to 200-800 mg/day PO divided q6-12hr
Potential toxic dose <6 years old: 3 mg/kg
Initiate treatment at lower dose and titrate to effect (monitor)
Schizophrenia
Initial 50-100 mg PO q8hr, THEN
200-800 mg/day PO divided q6-12hr
Debilitated patients: Initiate treatment at lower dose
Depressive disorders
25 mg PO q8hr; may titrate to effect (20-200 mg/day)
Interactions
Interaction Checker
No Results

Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor

Contraindicated (69)
- albuterol
albuterol and thioridazine both increase QTc interval. Contraindicated.
- alfuzosin
alfuzosin and thioridazine both increase QTc interval. Contraindicated.
- amiodarone
thioridazine and amiodarone both increase QTc interval. Contraindicated.
- amisulpride
amisulpride and thioridazine both increase QTc interval. Contraindicated.
amisulpride, thioridazine. Either increases toxicity of the other by Other (see comment). Contraindicated. Comment: Increases risk of neuroleptic malignant syndrome. - anagrelide
anagrelide and thioridazine both increase QTc interval. Contraindicated.
- apomorphine
apomorphine and thioridazine both increase QTc interval. Contraindicated.
- arformoterol
arformoterol and thioridazine both increase QTc interval. Contraindicated.
- aripiprazole
aripiprazole and thioridazine both increase QTc interval. Contraindicated.
- artemether
artemether and thioridazine both increase QTc interval. Contraindicated.
- asenapine
asenapine and thioridazine both increase QTc interval. Contraindicated.
- asenapine transdermal
asenapine transdermal and thioridazine both increase QTc interval. Contraindicated.
- atomoxetine
atomoxetine and thioridazine both increase QTc interval. Contraindicated.
- buprenorphine
buprenorphine and thioridazine both increase QTc interval. Contraindicated.
- buprenorphine buccal
buprenorphine buccal and thioridazine both increase QTc interval. Contraindicated.
- buprenorphine subdermal implant
buprenorphine subdermal implant and thioridazine both increase QTc interval. Contraindicated.
- buprenorphine transdermal
buprenorphine transdermal and thioridazine both increase QTc interval. Contraindicated.
- buprenorphine, long-acting injection
buprenorphine, long-acting injection and thioridazine both increase QTc interval. Contraindicated.
- ceritinib
ceritinib and thioridazine both increase QTc interval. Contraindicated.
- clomipramine
thioridazine will increase the level or effect of clomipramine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- clozapine
clozapine and thioridazine both increase QTc interval. Contraindicated.
- crizotinib
crizotinib and thioridazine both increase QTc interval. Contraindicated. Thioridazine is contraindicated with drugs that may prolong the QT interval.
- degarelix
degarelix and thioridazine both increase QTc interval. Contraindicated.
- desipramine
thioridazine will increase the level or effect of desipramine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- disopyramide
thioridazine and disopyramide both increase QTc interval. Contraindicated.
- dofetilide
dofetilide increases toxicity of thioridazine by QTc interval. Contraindicated.
- donepezil
donepezil and thioridazine both increase QTc interval. Contraindicated.
- doxepin
thioridazine will increase the level or effect of doxepin by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- eliglustat
thioridazine 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.
eliglustat and thioridazine both increase QTc interval. Contraindicated. - escitalopram
escitalopram increases toxicity of thioridazine by QTc interval. Contraindicated.
- fezolinetant
thioridazine will increase the level or effect of fezolinetant by affecting hepatic enzyme CYP1A2 metabolism. Contraindicated. Fezolinetant AUC and peak plasma concentration are increased if coadministered with drugs that are weak, moderate, or strong CYP1A2 inhibitors
- fingolimod
fingolimod and thioridazine both increase QTc interval. Contraindicated.
- fluoxetine
thioridazine will increase the level or effect of fluoxetine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
thioridazine and fluoxetine both increase QTc interval. Contraindicated.
fluoxetine increases levels of thioridazine by decreasing metabolism. Contraindicated. Risk of long QT syndrome. - gemifloxacin
gemifloxacin and thioridazine both increase QTc interval. Contraindicated.
- gilteritinib
gilteritinib and thioridazine both increase QTc interval. Contraindicated.
- goserelin
goserelin increases toxicity of thioridazine by QTc interval. Contraindicated. Increases risk of torsades de pointes.
- granisetron
granisetron and thioridazine both increase QTc interval. Contraindicated.
- hydroxyzine
hydroxyzine and thioridazine both increase QTc interval. Contraindicated.
- ibutilide
thioridazine and ibutilide both increase QTc interval. Contraindicated.
- imipramine
thioridazine will increase the level or effect of imipramine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- indapamide
thioridazine and indapamide both increase QTc interval. Contraindicated.
- isoflurane
isoflurane and thioridazine both increase QTc interval. Contraindicated.
- leuprolide
leuprolide increases toxicity of thioridazine by QTc interval. Contraindicated. Increases risk of torsades de pointes.
- lithium
lithium and thioridazine both increase QTc interval. Contraindicated.
- metrizamide
thioridazine, metrizamide. Mechanism: unknown. Contraindicated. Risk of seizure. D/C phenothiazine 24h before admin. of metrizamide.
- mifepristone
mifepristone, thioridazine. QTc interval. Contraindicated.
- mirtazapine
mirtazapine and thioridazine both increase QTc interval. Contraindicated.
- nortriptyline
thioridazine will increase the level or effect of nortriptyline by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- olanzapine
olanzapine and thioridazine both increase QTc interval. Contraindicated.
- oxaliplatin
oxaliplatin and thioridazine both increase QTc interval. Contraindicated.
- paroxetine
paroxetine increases levels of thioridazine by decreasing metabolism. Contraindicated. Risk of long QT syndrome.
- pasireotide
thioridazine and pasireotide both increase QTc interval. Contraindicated.
- pentamidine
thioridazine and pentamidine both increase QTc interval. Contraindicated.
- pimozide
thioridazine and pimozide both increase QTc interval. Contraindicated.
- primaquine
primaquine and thioridazine both increase QTc interval. Contraindicated.
- procainamide
thioridazine and procainamide both increase QTc interval. Contraindicated.
- quinidine
thioridazine and quinidine both increase QTc interval. Contraindicated.
- quinine
thioridazine and quinine both increase QTc interval. Contraindicated.
- rolapitant
rolapitant will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. Rolapitant moderately inhibits CYP2D6. Coadministration with thioridazine, a CYP2D6 substrate, causes a significant increase in thioridazine plasma concentration that may result in QT prolongation and torsades de pointes.
- sertraline
sertraline increases levels of thioridazine by decreasing metabolism. Contraindicated. Risk of long QT syndrome.
sertraline and thioridazine both increase QTc interval. Contraindicated. - sevoflurane
sevoflurane and thioridazine both increase QTc interval. Contraindicated.
- siponimod
siponimod and thioridazine both increase QTc interval. Contraindicated.
- solifenacin
solifenacin and thioridazine both increase QTc interval. Contraindicated.
- sorafenib
sorafenib and thioridazine both increase QTc interval. Contraindicated.
- sotalol
thioridazine and sotalol both increase QTc interval. Contraindicated.
- sunitinib
sunitinib and thioridazine both increase QTc interval. Contraindicated.
- tacrolimus
tacrolimus and thioridazine both increase QTc interval. Contraindicated.
- tetrabenazine
tetrabenazine and thioridazine both increase QTc interval. Contraindicated.
- toremifene
thioridazine and toremifene both increase QTc interval. Contraindicated. Concurrent use of thioridazine with other agents that prolong QTc interval is contraindicated.
- vorinostat
vorinostat and thioridazine both increase QTc interval. Contraindicated.
Serious - Use Alternative (129)
- adagrasib
adagrasib will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of adagrasib, a CYP2D6 inhibitor, with sensitive CYP2D6 substrates unless otherwise recommended in the prescribing information for these substrates.
adagrasib, thioridazine. 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. - aminolevulinic acid oral
aminolevulinic acid oral, thioridazine. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid administering other phototoxic drugs with aminolevulinic acid oral for 24 hr during perioperative period.
- aminolevulinic acid topical
thioridazine increases toxicity of aminolevulinic acid topical by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration of photosensitizing drugs may enhance the phototoxic reaction to photodynamic therapy with aminolevulinic acid.
- amiodarone
amiodarone will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
amiodarone increases levels of thioridazine by decreasing metabolism. Contraindicated. - amitriptyline
thioridazine and amitriptyline both increase QTc interval. Avoid or Use Alternate Drug.
- amoxapine
thioridazine and amoxapine both increase QTc interval. Avoid or Use Alternate Drug.
- apomorphine
thioridazine decreases effects of apomorphine by pharmacodynamic antagonism. Avoid or Use Alternate Drug.
- arsenic trioxide
thioridazine and arsenic trioxide both increase QTc interval. Avoid or Use Alternate Drug.
- artemether/lumefantrine
artemether/lumefantrine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
thioridazine and artemether/lumefantrine both increase QTc interval. Avoid or Use Alternate Drug. - asenapine
asenapine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- benzhydrocodone/acetaminophen
benzhydrocodone/acetaminophen, thioridazine. 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. Increased risk of hypotension if ability to maintain blood pressure has been compromised by a reduced blood volume or concurrent administration of certain CNS depressant drugs (eg, phenothiazines or general anesthetics).
benzhydrocodone/acetaminophen and thioridazine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate - bremelanotide
bremelanotide will decrease the level or effect of thioridazine by Other (see comment). Avoid or Use Alternate Drug. Bremelanotide may slow gastric emptying and potentially reduces the rate and extent of absorption of concomitantly administered oral medications. Avoid use when taking any oral drug that is dependent on threshold concentrations for efficacy. Interactions listed are representative examples and do not include all possible clinical examples.
- bromocriptine
thioridazine decreases effects of bromocriptine by pharmacodynamic antagonism. Avoid or Use Alternate Drug.
- buprenorphine subdermal implant
buprenorphine subdermal implant and thioridazine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
- buprenorphine transdermal
buprenorphine transdermal and thioridazine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
- bupropion
bupropion will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- cabergoline
thioridazine decreases effects of cabergoline by pharmacodynamic antagonism. Contraindicated.
- calcium/magnesium/potassium/sodium oxybates
thioridazine, 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.
- carvedilol
carvedilol, thioridazine. Either increases levels of the other by decreasing metabolism. Contraindicated. Not all beta blockers share this interaction (e.g., atenolol, nadolol, sotalol do not interact).
- celecoxib
celecoxib will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- chloroquine
chloroquine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- chlorpromazine
chlorpromazine and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.
- cimetidine
cimetidine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- citalopram
thioridazine and citalopram both increase QTc interval. Avoid or Use Alternate Drug. Thioridazine should be avoided in combination with drugs that are known to prolong QTc interval.
- clarithromycin
thioridazine and clarithromycin both increase QTc interval. Avoid or Use Alternate Drug.
- clomipramine
thioridazine and clomipramine both increase QTc interval. Avoid or Use Alternate Drug.
- dacomitinib
dacomitinib will increase the level or effect of thioridazine 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.
- darifenacin
darifenacin will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- desipramine
thioridazine and desipramine both increase QTc interval. Avoid or Use Alternate Drug.
- diphenhydramine
diphenhydramine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- dofetilide
thioridazine and dofetilide both increase QTc interval. Avoid or Use Alternate Drug.
- dopamine
thioridazine decreases effects of dopamine by pharmacodynamic antagonism. Contraindicated.
- dosulepin
thioridazine and dosulepin both increase QTc interval. Avoid or Use Alternate Drug.
- doxepin
thioridazine and doxepin both increase QTc interval. Avoid or Use Alternate Drug.
- dronedarone
dronedarone will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
thioridazine and dronedarone both increase QTc interval. Avoid or Use Alternate Drug. - droperidol
thioridazine and droperidol both increase QTc interval. Avoid or Use Alternate Drug.
- duloxetine
duloxetine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
thioridazine will increase the level or effect of duloxetine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. - encorafenib
encorafenib and thioridazine both increase QTc interval. Avoid or Use Alternate Drug. Encorafenib is associated with dose-dependent QTc interval prolongation. Avoid with drugs known to prolong QT interval.
- entrectinib
thioridazine and entrectinib both increase QTc interval. Avoid or Use Alternate Drug.
- epinephrine
epinephrine and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.
- epinephrine racemic
epinephrine racemic and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.
- eribulin
eribulin and thioridazine 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
thioridazine and erythromycin base both increase QTc interval. Avoid or Use Alternate Drug.
- erythromycin ethylsuccinate
thioridazine and erythromycin ethylsuccinate both increase QTc interval. Avoid or Use Alternate Drug.
- erythromycin lactobionate
thioridazine and erythromycin lactobionate both increase QTc interval. Avoid or Use Alternate Drug.
- erythromycin stearate
thioridazine and erythromycin stearate both increase QTc interval. Avoid or Use Alternate Drug.
- fentanyl
fentanyl, thioridazine. 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.
- fentanyl intranasal
fentanyl intranasal, thioridazine. 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.
- fentanyl transdermal
fentanyl transdermal, thioridazine. 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.
- fentanyl transmucosal
fentanyl transmucosal, thioridazine. 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.
- fexinidazole
fexinidazole and thioridazine both increase QTc interval. Avoid or Use Alternate Drug. Avoid coadministration of fexinidazole with drugs known to block potassium channels and/or prolong QT interval.
- fluconazole
thioridazine and fluconazole both increase QTc interval. Avoid or Use Alternate Drug.
- fluoxetine
fluoxetine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- fluphenazine
fluphenazine and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.
- fluvoxamine
fluvoxamine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP1A2 metabolism. Contraindicated.
fluvoxamine and thioridazine both increase QTc interval. Contraindicated. - formoterol
thioridazine and formoterol both increase QTc interval. Avoid or Use Alternate Drug.
- givosiran
givosiran will increase the level or effect of thioridazine 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
thioridazine and glasdegib both increase QTc interval. Avoid or Use Alternate Drug. If coadministration unavoidable, monitor for increased risk of QTc interval prolongation.
- haloperidol
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. - histrelin
histrelin increases toxicity of thioridazine by QTc interval. Avoid or Use Alternate Drug. Increases risk of torsades de pointes.
- hydrocodone
hydrocodone, thioridazine. 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. Increased risk of hypotension if ability to maintain blood pressure has been compromised by a reduced blood volume or concurrent administration of certain CNS depressant drugs (eg, phenothiazines or general anesthetics).
- hydroxychloroquine sulfate
hydroxychloroquine sulfate and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.
- imatinib
imatinib will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- imipramine
thioridazine and imipramine both increase QTc interval. Avoid or Use Alternate Drug.
- inotuzumab
inotuzumab and thioridazine 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.
- itraconazole
thioridazine and itraconazole both increase QTc interval. Avoid or Use Alternate Drug.
- ivosidenib
ivosidenib and thioridazine 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.
- ketoconazole
thioridazine and ketoconazole both increase QTc interval. Avoid or Use Alternate Drug.
- lefamulin
lefamulin and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.
- levodopa
thioridazine decreases effects of levodopa by pharmacodynamic antagonism. Avoid or Use Alternate Drug.
- levodopa inhaled
thioridazine decreases effects of levodopa inhaled by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Phenothiazine/1st generation antipsychotics inhibit dopamine D2 receptors in varying degrees.
- levoketoconazole
thioridazine and levoketoconazole both increase QTc interval. Avoid or Use Alternate Drug.
- lisuride
thioridazine decreases effects of lisuride by pharmacodynamic antagonism. Contraindicated.
- lofepramine
thioridazine and lofepramine both increase QTc interval. Avoid or Use Alternate Drug.
- lumefantrine
lumefantrine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
thioridazine and lumefantrine both increase QTc interval. Avoid or Use Alternate Drug. - macimorelin
macimorelin and thioridazine 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
thioridazine and maprotiline both increase QTc interval. Avoid or Use Alternate Drug.
- maraviroc
maraviroc will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- marijuana
marijuana will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- mefloquine
mefloquine increases toxicity of thioridazine by QTc interval. Avoid or Use Alternate Drug. Mefloquine may enhance the QTc prolonging effect of high risk QTc prolonging agents.
- methyl aminolevulinate
thioridazine, methyl aminolevulinate. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Each drug may increase the photosensitizing effect of the other.
- methyldopa
thioridazine decreases effects of methyldopa by pharmacodynamic antagonism. Contraindicated.
- metoclopramide intranasal
thioridazine will increase the level or effect of metoclopramide intranasal by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Concurrent use of metoclopramide intranasal and strong CYP2D6 inhibitors is not recommended since the metoclopramide intranasal dose cannot be adjusted.
thioridazine, 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.
thioridazine 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
metoprolol, thioridazine. Either increases levels of the other by decreasing metabolism. Contraindicated. Not all beta blockers share this interaction (e.g., atenolol, nadolol, sotalol do not interact).
- mobocertinib
mobocertinib and thioridazine both increase QTc interval. Avoid or Use Alternate Drug. If coadministration unavoidable, reduce mobocertinib dose and monitor QTc interval more frequently.
- moxifloxacin
thioridazine and moxifloxacin both increase QTc interval. Avoid or Use Alternate Drug.
- nilotinib
nilotinib will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
thioridazine and nilotinib both increase QTc interval. Avoid or Use Alternate Drug. - nortriptyline
thioridazine and nortriptyline both increase QTc interval. Avoid or Use Alternate Drug.
- octreotide
thioridazine and octreotide both increase QTc interval. Avoid or Use Alternate Drug.
- octreotide (Antidote)
thioridazine and octreotide (Antidote) both increase QTc interval. Avoid or Use Alternate Drug.
- olopatadine intranasal
thioridazine 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.
- ondansetron
thioridazine 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.
- panobinostat
thioridazine 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.
- parecoxib
parecoxib will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- paroxetine
paroxetine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
thioridazine will increase the level or effect of paroxetine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
thioridazine and paroxetine both increase QTc interval. Avoid or Use Alternate Drug. - perphenazine
perphenazine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
perphenazine and thioridazine both increase QTc interval. Avoid or Use Alternate Drug. - pimavanserin
pimavanserin and thioridazine both increase QTc interval. Avoid or Use Alternate Drug. Coadministration may increase the risk of QT prolongation and cardiac arrhythmia.
- pitolisant
thioridazine and pitolisant both increase QTc interval. Avoid or Use Alternate Drug.
- pramipexole
thioridazine decreases effects of pramipexole by pharmacodynamic antagonism. Contraindicated.
- prochlorperazine
prochlorperazine and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.
- promazine
promazine and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.
- promethazine
promethazine and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.
- propafenone
propafenone will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. The concurrent administration of thioridazine and agents that prolong the QT interval, such as Class I antiarrhythmic agents, is contraindicated.
thioridazine will increase the level or effect of propafenone by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. The concurrent administration of thioridazine and agents that prolong the QT interval, such as Class I antiarrhythmic agents, is contraindicated. - propranolol
thioridazine will increase the level or effect of propranolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Due to the potential for significant, possibly life-threatening, proarrhythmic effects, concurrent administration of thioridazine and propranolol is contraindicated.
propranolol, thioridazine. Either increases levels of the other by decreasing metabolism. Contraindicated. Not all beta blockers share this interaction (e.g., atenolol, nadolol, sotalol do not interact). - protriptyline
thioridazine and protriptyline both increase QTc interval. Avoid or Use Alternate Drug.
- quinacrine
quinacrine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- quinidine
quinidine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
quinidine, thioridazine. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Additive cardiac effects. - ranolazine
ranolazine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- ribociclib
ribociclib and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.
- ritonavir
ritonavir will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- ropinirole
thioridazine decreases effects of ropinirole by pharmacodynamic antagonism. Contraindicated.
- safinamide
thioridazine decreases effects of safinamide by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Dopamine antagonists may decrease safinamide effects and exacerbate Parkinson disease symptoms.
- selinexor
selinexor, thioridazine. 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.
- sertraline
sertraline will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.
- sodium oxybate
thioridazine, 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.
- tipranavir
tipranavir will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
- trazodone
thioridazine and trazodone both increase QTc interval. Avoid or Use Alternate Drug.
- tretinoin
thioridazine, tretinoin. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.
- tretinoin topical
thioridazine, tretinoin topical. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.
- trifluoperazine
thioridazine and trifluoperazine both increase QTc interval. Avoid or Use Alternate Drug.
- trimipramine
thioridazine and trimipramine both increase QTc interval. Avoid or Use Alternate Drug.
- triptorelin
triptorelin increases toxicity of thioridazine by QTc interval. Avoid or Use Alternate Drug. Increases risk of torsades de pointes.
- umeclidinium bromide/vilanterol inhaled
thioridazine 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
thioridazine, 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 increases levels of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Concomitant use of vemurafenib with agents with narrow therapeutic windows is not recommended as vemurafenib may alter their concentrations. If coadministration cannot be avoided, use caution and consider dose reduction of concomitant CYP2D6 substrate drug. Combination may increase risk QT prolongation.
- venlafaxine
venlafaxine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
thioridazine and venlafaxine both increase QTc interval. Avoid or Use Alternate Drug. - vilanterol/fluticasone furoate inhaled
thioridazine 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.
- yohimbe
yohimbe decreases effects of thioridazine by pharmacodynamic antagonism. Contraindicated.
- ziprasidone
thioridazine and ziprasidone both increase QTc interval. Avoid or Use Alternate Drug.
Monitor Closely (320)
- abiraterone
abiraterone increases levels of thioridazine 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 thioridazine by pharmacodynamic synergism. Use Caution/Monitor. Use of anticholinergic drugs after administration of botulinum toxin-containing products may potentiate systemic anticholinergic effects.
- aclidinium
aclidinium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of aclidinium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - acrivastine
acrivastine and thioridazine both increase sedation. Use Caution/Monitor.
- albiglutide
thioridazine, albiglutide. Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase or decrease glucose levels, monitor therapy closely when these agents are concurrently administered.
- albuterol
thioridazine increases and albuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- alfentanil
alfentanil and thioridazine both increase sedation. Use Caution/Monitor.
- alfuzosin
thioridazine and alfuzosin both increase QTc interval. Use Caution/Monitor.
- alprazolam
alprazolam and thioridazine both increase sedation. Use Caution/Monitor.
- amifampridine
thioridazine 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
thioridazine and amitriptyline both increase sedation. Use Caution/Monitor.
- amobarbital
amobarbital and thioridazine both increase sedation. Use Caution/Monitor.
- amoxapine
thioridazine and amoxapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
thioridazine and amoxapine both increase sedation. Use Caution/Monitor. - anticholinergic/sedative combos
anticholinergic/sedative combos decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
anticholinergic/sedative combos decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of anticholinergic/sedative combos by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - arformoterol
thioridazine increases and arformoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- aripiprazole
aripiprazole and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
aripiprazole and thioridazine both increase sedation. Use Caution/Monitor. - armodafinil
thioridazine increases and armodafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- asenapine
asenapine and thioridazine both increase sedation. Use Caution/Monitor.
- asenapine transdermal
asenapine transdermal and thioridazine both increase sedation. Use Caution/Monitor.
- atomoxetine
thioridazine will increase the level or effect of atomoxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- atracurium
atracurium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
atracurium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of atracurium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - atropine
atropine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
atropine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of atropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - atropine IV/IM
thioridazine increases effects of atropine IV/IM by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
atropine IV/IM decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
atropine IV/IM decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor. - avapritinib
avapritinib and thioridazine both increase sedation. Use Caution/Monitor.
- azelastine
azelastine and thioridazine both increase sedation. Use Caution/Monitor.
- azithromycin
thioridazine and azithromycin both increase QTc interval. Use Caution/Monitor.
- baclofen
baclofen and thioridazine both increase sedation. Use Caution/Monitor.
- bedaquiline
thioridazine and bedaquiline both increase QTc interval. Modify Therapy/Monitor Closely. ECG should be monitored closely
- belladonna alkaloids
belladonna alkaloids decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
belladonna alkaloids decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of belladonna alkaloids by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - belladonna and opium
belladonna and opium and thioridazine both increase sedation. Use Caution/Monitor.
belladonna and opium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
belladonna and opium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of belladonna and opium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - benperidol
benperidol and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
benperidol and thioridazine both increase sedation. Use Caution/Monitor. - benzhydrocodone/acetaminophen
thioridazine 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.
- benzphetamine
thioridazine increases and benzphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, benzphetamine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - benztropine
thioridazine increases effects of benztropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic adverse effects may be seen with concurrent use. .
- berotralstat
berotralstat will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Monitor or titrate substrate dose when berotralstat is coadministered with narrow therapeutic index drugs that are CYP2D6 substrates.
- brexanolone
brexanolone, thioridazine. Either increases toxicity of the other by sedation. Use Caution/Monitor.
- brexpiprazole
thioridazine 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.
brexpiprazole and thioridazine both increase sedation. Use Caution/Monitor. - brimonidine
brimonidine and thioridazine both increase sedation. Use Caution/Monitor.
- brivaracetam
brivaracetam and thioridazine both increase sedation. Use Caution/Monitor.
- brompheniramine
brompheniramine and thioridazine both increase sedation. Use Caution/Monitor.
- buprenorphine
buprenorphine and thioridazine both increase sedation. Use Caution/Monitor.
- buprenorphine buccal
buprenorphine buccal and thioridazine both increase sedation. Use Caution/Monitor.
- buprenorphine, long-acting injection
thioridazine 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.
- butabarbital
butabarbital and thioridazine both increase sedation. Use Caution/Monitor.
- butalbital
butalbital and thioridazine both increase sedation. Use Caution/Monitor.
- butorphanol
butorphanol and thioridazine both increase sedation. Use Caution/Monitor.
- caffeine
thioridazine increases and caffeine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- carbinoxamine
carbinoxamine and thioridazine both increase sedation. Use Caution/Monitor.
- carisoprodol
carisoprodol and thioridazine both increase sedation. Use Caution/Monitor.
- carvedilol
thioridazine will increase the level or effect of carvedilol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- cenobamate
cenobamate, thioridazine. Either increases effects of the other by sedation. Use Caution/Monitor.
- chloral hydrate
chloral hydrate and thioridazine both increase sedation. Use Caution/Monitor.
- chlordiazepoxide
chlordiazepoxide and thioridazine both increase sedation. Use Caution/Monitor.
- chloroquine
chloroquine increases toxicity of thioridazine by QTc interval. Use Caution/Monitor.
- chlorpheniramine
chlorpheniramine and thioridazine both increase sedation. Use Caution/Monitor.
- chlorpromazine
chlorpromazine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
chlorpromazine and thioridazine both increase sedation. Use Caution/Monitor. - chlorzoxazone
chlorzoxazone and thioridazine both increase sedation. Use Caution/Monitor.
- cigarette smoking
cigarette smoking decreases levels of thioridazine by increasing metabolism. Use Caution/Monitor. Interaction mainly seen w/chlorpromazine & thioridazine, but may occur w/other phenothiazines.
- cinnarizine
cinnarizine and thioridazine both increase sedation. Use Caution/Monitor.
- ciprofloxacin
ciprofloxacin and thioridazine 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 thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
cisatracurium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of cisatracurium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - clemastine
clemastine and thioridazine both increase sedation. Use Caution/Monitor.
- clobazam
clobazam will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Lower doses of drugs metabolized by CYP2D6 may be required when used concomitantly.
thioridazine, clobazam. Other (see comment). Use Caution/Monitor. Comment: Concomitant administration can increase the potential for CNS effects (e.g., increased sedation or respiratory depression). - clomipramine
thioridazine and clomipramine both increase sedation. Use Caution/Monitor.
- clonazepam
clonazepam and thioridazine both increase sedation. Use Caution/Monitor.
- clonidine
clonidine, thioridazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- clorazepate
clorazepate and thioridazine both increase sedation. Use Caution/Monitor.
- clozapine
clozapine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
clozapine and thioridazine both increase sedation. Use Caution/Monitor. - cobicistat
cobicistat will increase the level or effect of thioridazine by Other (see comment). Modify Therapy/Monitor Closely. A decrease in the dose of antipsychotics that are metabolized by CYP3A or CYP2D6 may be needed upon coadministration.
- codeine
thioridazine decreases effects of codeine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Prevents conversion of codeine to its active metabolite morphine.
codeine and thioridazine both increase sedation. Use Caution/Monitor. - cyclizine
cyclizine and thioridazine both increase sedation. Use Caution/Monitor.
cyclizine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
cyclizine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of cyclizine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - cyclobenzaprine
cyclobenzaprine and thioridazine both increase sedation. Use Caution/Monitor.
cyclobenzaprine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
cyclobenzaprine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of cyclobenzaprine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - cyproheptadine
cyproheptadine and thioridazine both increase sedation. Use Caution/Monitor.
- dantrolene
dantrolene and thioridazine both increase sedation. Use Caution/Monitor.
- daridorexant
thioridazine 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 decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
darifenacin decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of darifenacin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - dasatinib
thioridazine and dasatinib both increase QTc interval. Modify Therapy/Monitor Closely.
- desflurane
desflurane and thioridazine both increase sedation. Use Caution/Monitor.
- desipramine
thioridazine and desipramine both increase sedation. Use Caution/Monitor.
- desvenlafaxine
desvenlafaxine will increase the level or effect of thioridazine 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
thioridazine 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.
thioridazine 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).
thioridazine will increase the level or effect of deutetrabenazine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Strong CYP2D6 inhibitors increase the systemic exposure to the active dihydro-metabolites of deutetrabenazine by approximately 3-fold. Do not exceed 18 mg/dose and 36 mg/day of deutetrabenazine if coadministered with strong CYP2D6 inhibitors. - dexchlorpheniramine
dexchlorpheniramine and thioridazine both increase sedation. Use Caution/Monitor.
- dexfenfluramine
thioridazine increases and dexfenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, dexfenfluramine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - dexmedetomidine
dexmedetomidine and thioridazine both increase sedation. Use Caution/Monitor.
- dexmethylphenidate
thioridazine increases and dexmethylphenidate decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, dexmethylphenidate. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - dextroamphetamine
thioridazine increases and dextroamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, dextroamphetamine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - dextroamphetamine transdermal
thioridazine will increase the level or effect of dextroamphetamine transdermal by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Initiate with lower doses and monitor patients for signs and symptoms of serotonin syndrome, particularly during dextroamphetamine initiation and after a dosage increase. If serotonin syndrome occurs, discontinue dextroamphetamine transdermal and CYP2D6 inhibitor.
- dextromoramide
dextromoramide and thioridazine both increase sedation. Use Caution/Monitor.
- diamorphine
diamorphine and thioridazine both increase sedation. Use Caution/Monitor.
- diazepam
diazepam and thioridazine both increase sedation. Use Caution/Monitor.
- dicyclomine
dicyclomine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
dicyclomine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of dicyclomine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - diethylpropion
thioridazine increases and diethylpropion decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, diethylpropion. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - difelikefalin
difelikefalin and thioridazine both increase sedation. Use Caution/Monitor.
- difenoxin hcl
difenoxin hcl and thioridazine both increase sedation. Use Caution/Monitor.
- dimenhydrinate
dimenhydrinate and thioridazine both increase sedation. Use Caution/Monitor.
- diphenhydramine
diphenhydramine and thioridazine both increase sedation. Use Caution/Monitor.
diphenhydramine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
diphenhydramine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - diphenoxylate hcl
diphenoxylate hcl and thioridazine both increase sedation. Use Caution/Monitor.
- dipipanone
dipipanone and thioridazine both increase sedation. Use Caution/Monitor.
- dobutamine
thioridazine increases and dobutamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, dobutamine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - dolasetron
thioridazine and dolasetron both increase QTc interval. Modify Therapy/Monitor Closely.
- donepezil transdermal
donepezil transdermal, thioridazine. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.
- dopamine
thioridazine increases and dopamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, dopamine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - dopexamine
thioridazine increases and dopexamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- dosulepin
thioridazine and dosulepin both increase sedation. Use Caution/Monitor.
- doxepin
thioridazine and doxepin both increase sedation. Use Caution/Monitor.
- doxylamine
doxylamine and thioridazine both increase sedation. Use Caution/Monitor.
- droperidol
droperidol and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
droperidol and thioridazine both increase sedation. Use Caution/Monitor. - eliglustat
eliglustat increases levels of thioridazine 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 thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP2D6 inhibitor; a decrease in dose of the neuroleptic may be needed when coadministered.
- ephedrine
thioridazine increases and ephedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, ephedrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - epinephrine
thioridazine increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, epinephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
thioridazine decreases effects of epinephrine by pharmacodynamic antagonism. Use Caution/Monitor. Block pressor response to epinephrine, which may result in severe hypotension and tachycardia. - epinephrine racemic
thioridazine increases and epinephrine racemic decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine decreases effects of epinephrine racemic by pharmacodynamic antagonism. Use Caution/Monitor. Block pressor response to epinephrine, which may result in severe hypotension and tachycardia. - esketamine intranasal
esketamine intranasal, thioridazine. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely.
- estazolam
estazolam and thioridazine both increase sedation. Use Caution/Monitor.
- ethanol
thioridazine and ethanol both increase sedation. Use Caution/Monitor.
- ezogabine
ezogabine, thioridazine. 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 thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.
- fenfluramine
thioridazine increases and fenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, fenfluramine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - ferric maltol
ferric maltol, thioridazine. Either increases levels of the other by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Coadministration of ferric maltol with certain oral medications may decrease the bioavailability of either ferric maltol and some oral drugs. For oral drugs where reductions in bioavailability may cause clinically significant effects on its safety or efficacy, separate administration of ferric maltol from these drugs. Duration of separation may depend on the absorption of the medication concomitantly administered (eg, time to peak concentration, whether the drug is an immediate or extended release product).
- fesoterodine
fesoterodine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
fesoterodine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - flavoxate
flavoxate decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
flavoxate decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of flavoxate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - flecainide
thioridazine will increase the level or effect of flecainide by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
thioridazine and flecainide both increase QTc interval. Modify Therapy/Monitor Closely. - fluphenazine
fluphenazine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
fluphenazine and thioridazine both increase sedation. Use Caution/Monitor. - flurazepam
flurazepam and thioridazine both increase sedation. Use Caution/Monitor.
- formoterol
thioridazine increases and formoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- foscarnet
thioridazine and foscarnet both increase QTc interval. Modify Therapy/Monitor Closely.
- fostemsavir
thioridazine and fostemsavir both increase QTc interval. Use Caution/Monitor. QTc prolongation reported with higher than recommended doses of fostemsavir.
- gadobenate
gadobenate and thioridazine both increase QTc interval. Use Caution/Monitor.
- ganaxolone
thioridazine and ganaxolone both increase sedation. Use Caution/Monitor.
- gemtuzumab
thioridazine and gemtuzumab both increase QTc interval. Use Caution/Monitor.
- glycopyrrolate
thioridazine increases effects of glycopyrrolate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
- glycopyrrolate inhaled
glycopyrrolate inhaled decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
glycopyrrolate inhaled decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of glycopyrrolate inhaled by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - glycopyrronium tosylate topical
glycopyrronium tosylate topical, thioridazine. 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.
- guanfacine
guanfacine, thioridazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.
- guselkumab
guselkumab, thioridazine. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, normalizing the formation of CYP450 enzymes. Upon initiation or discontinuation of guselkumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.
- haloperidol
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. - henbane
henbane decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
henbane decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of henbane by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - homatropine
homatropine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
homatropine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of homatropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - hydrocodone
thioridazine 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
thioridazine will increase the level or effect of hydromorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
hydromorphone and thioridazine both increase sedation. Use Caution/Monitor. - hydroxyzine
hydroxyzine and thioridazine both increase sedation. Use Caution/Monitor.
- hyoscyamine
hyoscyamine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - hyoscyamine spray
thioridazine increases effects of hyoscyamine spray by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
hyoscyamine spray decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
hyoscyamine spray decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor. - iloperidone
thioridazine will increase the level or effect of iloperidone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
iloperidone and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
thioridazine and iloperidone both increase QTc interval. Modify Therapy/Monitor Closely.
iloperidone and thioridazine both increase sedation. Use Caution/Monitor. - imipramine
thioridazine and imipramine both increase sedation. Use Caution/Monitor.
- incobotulinumtoxinA
thioridazine increases effects of incobotulinumtoxinA by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.
- indacaterol, inhaled
indacaterol, inhaled, thioridazine. QTc interval. Use Caution/Monitor. Drugs that are known to prolong the QTc interval may have an increased the risk of ventricular arrhythmias.
- insulin degludec
thioridazine decreases effects of insulin degludec by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.
- insulin degludec/insulin aspart
thioridazine decreases effects of insulin degludec/insulin aspart by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.
- insulin inhaled
thioridazine decreases effects of insulin inhaled by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.
- ipratropium
ipratropium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
ipratropium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of ipratropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - isoproterenol
thioridazine increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, isoproterenol. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - ketamine
ketamine and thioridazine both increase sedation. Use Caution/Monitor.
- ketotifen, ophthalmic
thioridazine and ketotifen, ophthalmic both increase sedation. Use Caution/Monitor.
- lapatinib
thioridazine and lapatinib both increase QTc interval. Modify Therapy/Monitor Closely.
- lasmiditan
lasmiditan, thioridazine. 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 will increase the level or effect of thioridazine by sedation. Modify Therapy/Monitor Closely. Dosage adjustment may be necessary if lemborexant is coadministered with other CNS depressants because of potentially additive effects.
- lenvatinib
thioridazine and lenvatinib both increase QTc interval. Use Caution/Monitor. Lenvatinib prescribing information recommends monitoring ECG closely when coadministered with QT prolonging drugs.
- levalbuterol
thioridazine increases and levalbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- levofloxacin
thioridazine and levofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.
- levorphanol
levorphanol and thioridazine both increase sedation. Use Caution/Monitor.
- liraglutide
thioridazine, liraglutide. Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase or decrease glucose levels, monitor therapy closely when these agents are concurrently administered.
- lisdexamfetamine
thioridazine increases and lisdexamfetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, lisdexamfetamine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - lithium
lithium, thioridazine. Other (see comment). Use Caution/Monitor. Comment: Risk of neurotoxicity. Multiple mechanisms involved.
- lofepramine
thioridazine will increase the level or effect of lofepramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
thioridazine and lofepramine both increase sedation. Use Caution/Monitor. - lofexidine
thioridazine and lofexidine both increase sedation. Use Caution/Monitor.
thioridazine will increase the level or effect of lofexidine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Concomitant use of lofexidine with strong CYP2D6 inhibitors may increase lofexidine plasma levels. Monitor for symptoms of orthostasis and bradycardia if coadministered with a CYP2D6 inhibitor. Consider lofexidine dose reduction.
thioridazine and lofexidine both increase QTc interval. Use Caution/Monitor. ECG monitoring is recommended. - loprazolam
loprazolam and thioridazine both increase sedation. Use Caution/Monitor.
- lorazepam
lorazepam and thioridazine both increase sedation. Use Caution/Monitor.
- lorcaserin
lorcaserin will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- lormetazepam
lormetazepam and thioridazine both increase sedation. Use Caution/Monitor.
- loxapine
loxapine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
loxapine and thioridazine both increase sedation. Use Caution/Monitor. - loxapine inhaled
loxapine inhaled and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
loxapine inhaled and thioridazine both increase sedation. Use Caution/Monitor. - lurasidone
lurasidone, thioridazine. 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
thioridazine and maprotiline both increase sedation. Use Caution/Monitor.
- marijuana
thioridazine and marijuana both increase sedation. Use Caution/Monitor.
- meclizine
meclizine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
meclizine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of meclizine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - melatonin
thioridazine and melatonin both increase sedation. Use Caution/Monitor.
- meperidine
meperidine and thioridazine both increase sedation. Use Caution/Monitor.
- meprobamate
thioridazine and meprobamate both increase sedation. Use Caution/Monitor.
- metaproterenol
thioridazine increases and metaproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- metaxalone
metaxalone and thioridazine both increase sedation. Use Caution/Monitor.
- metformin
thioridazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.
- methadone
thioridazine and methadone both increase QTc interval. Modify Therapy/Monitor Closely.
methadone and thioridazine both increase sedation. Use Caution/Monitor. - methamphetamine
thioridazine will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
thioridazine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, methamphetamine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - methocarbamol
methocarbamol and thioridazine both increase sedation. Use Caution/Monitor.
- methoxsalen
methoxsalen, thioridazine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive photosensitizing effects.
- methscopolamine
methscopolamine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
methscopolamine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of methscopolamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - methylenedioxymethamphetamine
thioridazine increases and methylenedioxymethamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, methylenedioxymethamphetamine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - methylphenidate
thioridazine, methylphenidate. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
- metoclopramide
thioridazine and metoclopramide both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
- metoprolol
thioridazine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- mexiletine
thioridazine will increase the level or effect of mexiletine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- midazolam
midazolam and thioridazine both increase sedation. Use Caution/Monitor.
- midazolam intranasal
midazolam intranasal, thioridazine. 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
thioridazine increases and midodrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, midodrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - mirabegron
mirabegron will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- mirtazapine
thioridazine and mirtazapine both increase sedation. Use Caution/Monitor.
- modafinil
thioridazine increases and modafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- morphine
thioridazine will increase the level or effect of morphine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
morphine and thioridazine both increase sedation. Use Caution/Monitor. - motherwort
thioridazine and motherwort both increase sedation. Use Caution/Monitor.
- moxonidine
thioridazine and moxonidine both increase sedation. Use Caution/Monitor.
- nabilone
thioridazine and nabilone both increase sedation. Use Caution/Monitor.
- nalbuphine
nalbuphine and thioridazine both increase sedation. Use Caution/Monitor.
- nebivolol
thioridazine will increase the level or effect of nebivolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- norepinephrine
thioridazine increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, norepinephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - nortriptyline
thioridazine and nortriptyline both increase sedation. Use Caution/Monitor.
- ofloxacin
thioridazine and ofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.
- olanzapine
olanzapine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
olanzapine and thioridazine both increase sedation. Use Caution/Monitor. - oliceridine
thioridazine 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, thioridazine. 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. Increased risk of hypotension if ability to maintain blood pressure has been compromised by a reduced blood volume or concurrent administration of certain CNS depressant drugs (eg, phenothiazines or general anesthetics). - olodaterol inhaled
thioridazine 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
- omaveloxolone
omaveloxolone will decrease the level or effect of thioridazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Omaveloxolone may reduce systemic exposure of sensitive CYP3A4 substrates. Check prescribing information of substrate if dosage modification is needed.
- onabotulinumtoxinA
onabotulinumtoxinA decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
onabotulinumtoxinA decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of onabotulinumtoxinA by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - opium tincture
opium tincture and thioridazine both increase sedation. Use Caution/Monitor.
- orphenadrine
orphenadrine and thioridazine both increase sedation. Use Caution/Monitor.
- osilodrostat
osilodrostat and thioridazine both increase QTc interval. Use Caution/Monitor.
- osimertinib
osimertinib and thioridazine 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 thioridazine 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 thioridazine both increase sedation. Use Caution/Monitor.
- oxybutynin
oxybutynin decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
oxybutynin decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of oxybutynin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - oxybutynin topical
oxybutynin topical decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
oxybutynin topical decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of oxybutynin topical by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - oxybutynin transdermal
oxybutynin transdermal decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
oxybutynin transdermal decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of oxybutynin transdermal by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - oxycodone
thioridazine will increase the level or effect of oxycodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
oxycodone and thioridazine both increase sedation. Use Caution/Monitor. - oxymorphone
thioridazine will increase the level or effect of oxymorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
oxymorphone and thioridazine both increase sedation. Use Caution/Monitor. - ozanimod
ozanimod and thioridazine 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.
- paliperidone
paliperidone and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
thioridazine and paliperidone both increase QTc interval. Modify Therapy/Monitor Closely.
paliperidone and thioridazine both increase sedation. Use Caution/Monitor. - pancuronium
pancuronium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
pancuronium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of pancuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - panobinostat
panobinostat will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Panobinostat can increase the levels and effects of sensitive CYP2D6 substrates or those with a narrow therapeutic index CYP2D6.
- papaveretum
papaveretum and thioridazine both increase sedation. Use Caution/Monitor.
- papaverine
thioridazine and papaverine both increase sedation. Use Caution/Monitor.
- pazopanib
thioridazine and pazopanib both increase QTc interval. Use Caution/Monitor.
- peginterferon alfa 2b
peginterferon alfa 2b, thioridazine. 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 thioridazine both increase sedation. Use Caution/Monitor.
- pentobarbital
pentobarbital and thioridazine both increase sedation. Use Caution/Monitor.
- perphenazine
perphenazine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
perphenazine and thioridazine both increase sedation. Use Caution/Monitor. - phendimetrazine
thioridazine increases and phendimetrazine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, phendimetrazine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - phenobarbital
phenobarbital and thioridazine both increase sedation. Use Caution/Monitor.
- phentermine
thioridazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, phentermine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - phenylephrine
thioridazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - phenylephrine PO
thioridazine increases and phenylephrine PO decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. .
thioridazine, phenylephrine PO. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - pholcodine
thioridazine and pholcodine both increase sedation. Use Caution/Monitor.
- pimozide
pimozide and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
pimozide and thioridazine both increase sedation. Use Caution/Monitor. - pirbuterol
thioridazine increases and pirbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- pitolisant
thioridazine will increase the level or effect of pitolisant by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If coadministered with strong CYP2D6 inhibitors, initiate pitolisant at 8.9 mg/day and increase after 7 days to maximum of 17.8 mg/day. For patients currently taking pitolisant, reduce pitolisant dose by half upon initiating strong CYP2D6 inhibitors.
- porfimer
thioridazine, porfimer. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Enhanced photosensitivity.
- posaconazole
thioridazine and posaconazole both increase QTc interval. Modify Therapy/Monitor Closely.
- pralidoxime
pralidoxime decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
pralidoxime decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of pralidoxime by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - primidone
primidone and thioridazine both increase sedation. Use Caution/Monitor.
- procarbazine
procarbazine, thioridazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Excessive sedation.
- prochlorperazine
prochlorperazine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
prochlorperazine and thioridazine both increase sedation. Use Caution/Monitor. - promethazine
promethazine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
promethazine and thioridazine both increase sedation. Use Caution/Monitor. - propantheline
propantheline decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
propantheline decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of propantheline by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - propofol
propofol and thioridazine both increase sedation. Use Caution/Monitor.
- propylhexedrine
thioridazine increases and propylhexedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, propylhexedrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - protriptyline
thioridazine and protriptyline both increase sedation. Use Caution/Monitor.
- pseudoephedrine
thioridazine, pseudoephedrine. Mechanism: unknown. Use Caution/Monitor. Consider avoiding use of pseudoephedrine in patients receiving phenothiazines (especially thioridazine) due to the potential risk of cardiac arrhythmia or sudden death. Monitor for evidence of ventricular arrhythmias during concomitant use.
- quazepam
quazepam and thioridazine both increase sedation. Use Caution/Monitor.
- quetiapine
quetiapine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
quetiapine and thioridazine both increase sedation. Use Caution/Monitor.
quetiapine, thioridazine. 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. - ramelteon
thioridazine and ramelteon both increase sedation. Use Caution/Monitor.
- ranolazine
thioridazine and ranolazine both increase QTc interval. Modify Therapy/Monitor Closely.
- rapacuronium
rapacuronium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
rapacuronium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of rapacuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - rilpivirine
rilpivirine increases toxicity of thioridazine by QTc interval. Use Caution/Monitor. Rilpivirine should be used with caution when co-administered with a drug with a known risk of Torsade de Pointes.
- rimabotulinumtoxinB
thioridazine, 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.
- risperidone
risperidone and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
thioridazine and risperidone both increase QTc interval. Modify Therapy/Monitor Closely.
risperidone and thioridazine both increase sedation. Use Caution/Monitor. - rocuronium
rocuronium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
rocuronium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of rocuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - romidepsin
thioridazine and romidepsin both increase QTc interval. Modify Therapy/Monitor Closely.
- ropeginterferon alfa 2b
ropeginterferon alfa 2b will increase the level or effect of thioridazine by Other (see comment). Use Caution/Monitor. Certain proinflammatory cytokines, including interferons, can suppress CYP450 enzymes resulting in increased exposures of some CYP substrates. Therefore, monitor patients who are receiving concomitant drugs that are CYP450 substrates with a narrow therapeutic index from toxicities to such drugs.
- salmeterol
thioridazine increases and salmeterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- saquinavir
saquinavir, thioridazine. Either increases toxicity of the other by QTc interval. Modify Therapy/Monitor Closely. Use alternatives if available.
- scopolamine
scopolamine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
scopolamine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of scopolamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - scullcap
thioridazine and scullcap both increase sedation. Use Caution/Monitor.
- secobarbital
secobarbital and thioridazine both increase sedation. Use Caution/Monitor.
- selpercatinib
selpercatinib increases toxicity of thioridazine by QTc interval. Use Caution/Monitor.
- serdexmethylphenidate/dexmethylphenidate
thioridazine, serdexmethylphenidate/dexmethylphenidate. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
- sevoflurane
sevoflurane and thioridazine both increase sedation. Use Caution/Monitor.
- shepherd's purse
thioridazine and shepherd's purse both increase sedation. Use Caution/Monitor.
- smoking
smoking decreases levels of thioridazine by increasing metabolism. Use Caution/Monitor. Interaction mainly seen w/chlorpromazine & thioridazine, but may occur w/other phenothiazines.
- sodium sulfate/?magnesium sulfate/potassium chloride
sodium sulfate/?magnesium sulfate/potassium chloride increases toxicity of thioridazine by QTc interval. Use Caution/Monitor. Consider predose and post-colonoscopy ECGs in patients at increased risk of serious cardiac arrhythmias. .
- sodium sulfate/potassium sulfate/magnesium sulfate
sodium sulfate/potassium sulfate/magnesium sulfate increases toxicity of thioridazine by QTc interval. Use Caution/Monitor. Consider predose and post-colonoscopy ECGs in patients at increased risk of serious cardiac arrhythmias. .
- solifenacin
solifenacin decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
solifenacin decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of solifenacin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - stiripentol
stiripentol, thioridazine. Either decreases toxicity 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 thioridazine both increase sedation. Use Caution/Monitor.
- sulfamethoxazole
thioridazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.
- tamsulosin
thioridazine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- tapentadol
tapentadol and thioridazine both increase sedation. Use Caution/Monitor.
- teclistamab
teclistamab will increase the level or effect of thioridazine by altering metabolism. Use Caution/Monitor. Teclistamab causes release of cytokines that may suppress activity of CYP450 enzymes, resulting in increased exposure of CYP substrates. Monitor for increased concentrations or toxicities of sensitive CYP substrates. Adjust dose of CYP substrate drug as needed.
- teduglutide
teduglutide increases levels of thioridazine 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
thioridazine and telavancin both increase QTc interval. Modify Therapy/Monitor Closely.
- temazepam
temazepam and thioridazine both increase sedation. Use Caution/Monitor.
- terbinafine
terbinafine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.
- terbutaline
thioridazine increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- tetrabenazine
thioridazine and tetrabenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely.
- thiothixene
thioridazine and thiothixene both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
thioridazine and thiothixene both increase sedation. Use Caution/Monitor. - timolol
thioridazine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- tiotropium
tiotropium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
tiotropium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of tiotropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - tobacco use
tobacco use decreases levels of thioridazine by increasing metabolism. Use Caution/Monitor. Interaction mainly seen w/chlorpromazine & thioridazine, but may occur w/other phenothiazines.
- tolterodine
tolterodine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
tolterodine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - topiramate
thioridazine and topiramate both increase sedation. Modify Therapy/Monitor Closely.
- tramadol
thioridazine decreases effects of tramadol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Decreased conversion of tramadol to active metabolite.
tramadol and thioridazine both increase sedation. Use Caution/Monitor.
thioridazine decreases effects of tramadol by decreasing metabolism. Use Caution/Monitor. Decreased conversion of tramadol to active metabolite. - trazodone
thioridazine and trazodone both increase sedation. Use Caution/Monitor.
- triazolam
triazolam and thioridazine both increase sedation. Use Caution/Monitor.
- triclabendazole
triclabendazole and thioridazine both increase QTc interval. Use Caution/Monitor.
- triclofos
triclofos and thioridazine both increase sedation. Use Caution/Monitor.
- trifluoperazine
thioridazine and trifluoperazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
thioridazine and trifluoperazine both increase sedation. Use Caution/Monitor. - trihexyphenidyl
trihexyphenidyl decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects. - trimethoprim
thioridazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.
- trimipramine
thioridazine and trimipramine both increase sedation. Use Caution/Monitor.
- triprolidine
triprolidine and thioridazine both increase sedation. Use Caution/Monitor.
- trofinetide
trofinetide will increase the level or effect of thioridazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor CYP3A4 substrates for which a small increase in plasma concentration may lead to serious toxicities if coadministered with trofinetide (a weak CYP3A4 inhibitor).
- tropisetron
thioridazine and tropisetron both increase QTc interval. Modify Therapy/Monitor Closely.
- trospium chloride
trospium chloride decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
trospium chloride decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of trospium chloride by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - ustekinumab
ustekinumab, thioridazine. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, normalizing the formation of CYP450 enzymes. Upon initiation or discontinuation of ustekinumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.
- vecuronium
vecuronium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.
vecuronium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.
thioridazine increases effects of vecuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia. - voclosporin
voclosporin, thioridazine. Either increases effects of the other by QTc interval. Use Caution/Monitor.
- voriconazole
thioridazine and voriconazole both increase QTc interval. Modify Therapy/Monitor Closely.
- xylometazoline
thioridazine increases and xylometazoline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, xylometazoline. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - yohimbine
thioridazine increases and yohimbine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine, yohimbine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. - ziconotide
thioridazine and ziconotide both increase sedation. Use Caution/Monitor.
- ziprasidone
thioridazine and ziprasidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
thioridazine and ziprasidone both increase sedation. Use Caution/Monitor. - zolpidem
thioridazine will increase the level or effect of zolpidem by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Additive effect of decreased alertness and psychomotor performance
- zotepine
thioridazine and zotepine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.
thioridazine and zotepine both increase sedation. Use Caution/Monitor.
Minor (70)
- amantadine
amantadine increases toxicity of thioridazine by pharmacodynamic synergism. Minor/Significance Unknown. May increase Parkinsonian tremor.
- amitriptyline
amitriptyline, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
amitriptyline, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - amobarbital
thioridazine decreases levels of amobarbital by unspecified interaction mechanism. Minor/Significance Unknown.
- amoxapine
amoxapine, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
amoxapine, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - aripiprazole
thioridazine will increase the level or effect of aripiprazole by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- atropine
thioridazine increases toxicity of atropine by unknown mechanism. Minor/Significance Unknown.
- atropine IV/IM
thioridazine increases toxicity of atropine IV/IM by unknown mechanism. Minor/Significance Unknown.
- benazepril
thioridazine, benazepril. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. May increase risk of hypotension.
- brimonidine
brimonidine increases effects of thioridazine by pharmacodynamic synergism. Minor/Significance Unknown. Increased CNS depression.
- bupropion
thioridazine increases toxicity of bupropion by unspecified interaction mechanism. Minor/Significance Unknown. May lower seizure threshold; keep bupropion dose as low as possible.
- butabarbital
thioridazine decreases levels of butabarbital by unspecified interaction mechanism. Minor/Significance Unknown.
- butalbital
thioridazine decreases levels of butalbital by unspecified interaction mechanism. Minor/Significance Unknown.
- captopril
thioridazine increases effects of captopril by unspecified interaction mechanism. Minor/Significance Unknown.
- chasteberry
chasteberry decreases effects of thioridazine by pharmacodynamic antagonism. Minor/Significance Unknown. (Theoretical interaction).
- chloroquine
chloroquine increases levels of thioridazine by decreasing metabolism. Minor/Significance Unknown.
- chlorpromazine
thioridazine will increase the level or effect of chlorpromazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- clomipramine
clomipramine, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
clomipramine, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - codeine
thioridazine decreases effects of codeine by decreasing metabolism. Minor/Significance Unknown. Decreased conversion of codeine to active metabolite morphine.
- desipramine
desipramine, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
desipramine, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - dexfenfluramine
thioridazine will increase the level or effect of dexfenfluramine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- dextroamphetamine
thioridazine will increase the level or effect of dextroamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- dextromethorphan
thioridazine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- donepezil
thioridazine will increase the level or effect of donepezil by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- doxepin
doxepin, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
doxepin, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - enalapril
thioridazine increases effects of enalapril by unspecified interaction mechanism. Minor/Significance Unknown.
- encainide
thioridazine will increase the level or effect of encainide by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- ethanol
ethanol, thioridazine. Either increases toxicity of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive CNS depression.
- eucalyptus
thioridazine and eucalyptus both increase sedation. Minor/Significance Unknown.
- fesoterodine
thioridazine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- fluphenazine
thioridazine will increase the level or effect of fluphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- fosinopril
thioridazine increases effects of fosinopril by unspecified interaction mechanism. Minor/Significance Unknown.
- galantamine
thioridazine will increase the level or effect of galantamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- glycopyrrolate
thioridazine increases toxicity of glycopyrrolate by unknown mechanism. Minor/Significance Unknown.
- glycopyrrolate inhaled
thioridazine increases toxicity of glycopyrrolate inhaled by unknown mechanism. Minor/Significance Unknown.
- imidapril
thioridazine increases effects of imidapril by unspecified interaction mechanism. Minor/Significance Unknown.
- imipramine
imipramine, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
imipramine, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - lisinopril
thioridazine increases effects of lisinopril by unspecified interaction mechanism. Minor/Significance Unknown.
- lofepramine
lofepramine, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
lofepramine, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - loratadine
thioridazine will increase the level or effect of loratadine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- maprotiline
maprotiline, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
maprotiline, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - metyrapone
thioridazine decreases effects of metyrapone by unspecified interaction mechanism. Minor/Significance Unknown.
- metyrosine
metyrosine increases toxicity of thioridazine by pharmacodynamic synergism. Minor/Significance Unknown. Increased extrapyramidal symptoms.
- moexipril
thioridazine increases effects of moexipril by unspecified interaction mechanism. Minor/Significance Unknown.
- nortriptyline
nortriptyline, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
nortriptyline, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - oxybutynin
oxybutynin increases toxicity of thioridazine by unspecified interaction mechanism. Minor/Significance Unknown.
- oxybutynin topical
oxybutynin topical increases toxicity of thioridazine by unspecified interaction mechanism. Minor/Significance Unknown.
- oxybutynin transdermal
oxybutynin transdermal increases toxicity of thioridazine by unspecified interaction mechanism. Minor/Significance Unknown.
- oxycodone
thioridazine decreases effects of oxycodone by decreasing metabolism. Minor/Significance Unknown. Decreased conversion of oxycodone to active metabolite morphine.
- pentobarbital
thioridazine decreases levels of pentobarbital by unspecified interaction mechanism. Minor/Significance Unknown.
- perhexiline
thioridazine will increase the level or effect of perhexiline by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- perindopril
thioridazine increases effects of perindopril by unspecified interaction mechanism. Minor/Significance Unknown.
- perphenazine
thioridazine will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- phenobarbital
thioridazine decreases levels of phenobarbital by unspecified interaction mechanism. Minor/Significance Unknown.
- primidone
thioridazine decreases levels of primidone by unspecified interaction mechanism. Minor/Significance Unknown.
- prochlorperazine
thioridazine will increase the level or effect of prochlorperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- promazine
thioridazine will increase the level or effect of promazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- promethazine
thioridazine will increase the level or effect of promethazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- protriptyline
protriptyline, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
protriptyline, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - pyrimethamine
pyrimethamine increases levels of thioridazine by decreasing metabolism. Minor/Significance Unknown.
- quinapril
thioridazine increases effects of quinapril by unspecified interaction mechanism. Minor/Significance Unknown.
- ramipril
thioridazine increases effects of ramipril by unspecified interaction mechanism. Minor/Significance Unknown.
- risperidone
thioridazine will increase the level or effect of risperidone by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- sage
thioridazine and sage both increase sedation. Minor/Significance Unknown.
- secobarbital
thioridazine decreases levels of secobarbital by unspecified interaction mechanism. Minor/Significance Unknown.
- tolterodine
thioridazine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- trandolapril
thioridazine increases effects of trandolapril by unspecified interaction mechanism. Minor/Significance Unknown.
- trazodone
trazodone, thioridazine. Either increases toxicity of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive hypotensive effects.
trazodone, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects. - trifluoperazine
thioridazine will increase the level or effect of trifluoperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- trimipramine
trimipramine, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.
trimipramine, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects. - tropisetron
thioridazine will increase the level or effect of tropisetron by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
Adverse Effects
Frequency Not Defined
EPS (muscle stiffness, dystonia, parkinsonism, tardive dyskinesia, akathisia) (60%)
NMS (infrequent but serious)
Sedation
Anticholinergic effects
Weight gain
Oligomenorrhea/amenorrhea
Erectile dysfunction
Insomnia
Restlessness
Anxiety
Euphoria
Agitation
Depression
Weakness
Headache
Cerebral edema
Poikilothermia
Orthostatic hypotension
Tachycardia
Dizziness
Lens opacities (prolonged use)
Anorexia
Dyspepsia
Constipation
Ileus
Blood dyscrasia
ECG changes
Photosensitivity
Pruritis
Diarrhea
Galactorrhea
Ejaculatory disorder
Seizure (rare)
Priapism (rare)
Cholestatic jaundice (rare)
Warnings
Black Box Warnings
Patients with dementia-related psychosis who are treated with antipsychotic drugs are at an increased risk of death as shown in short-term controlled trials; the deaths appeared to be either cardiovascular (eg, heart failure, sudden death) or infectious (eg, pneumonia) in nature; this drug is not approved for the treatment of patients with dementia-related psychosis
Shown to prolong QTc interval in a dose-related manner; drugs with this potential have been associated with Torsades de pointes type arrhythmias and sudden death; due to potential for significant, possibly life-threatening, proarrhythmic effects, therapy should be reserved for use in treatment of schizophrenic patients who fail to show acceptable response to adequate courses of treatment with other antipsychotic drugs, either because of insufficient effectiveness or inability to achieve effective dose due to intolerable adverse effects from those drugs
Contraindications
Documented hypersensitivity to phenothiazines
Coadministration with cytochrome P450 2D6 isozyme inhibitors (eg, fluoxetine and paroxetine) and certain other drugs (eg, fluvoxamine, propranolol, and pindolol)
Patients who are known to have a genetic defect leading to reduced levels of activity of P450 2D6
Patients with hypertensive or hypotensive heart disease of extreme degree
Patients in comatose state
Severe CNS depression
Severe hyper-/hypotensive heart disease
Cautions
Avoid using in children with suspected Reye's syndrome
Hypotension may be particularly severe in patients with pheochromocytoma or mitral insufficiency
Depresses hypothalamic thermoregulatory mechanism; exposure to extreme temperatures may cause hypo- or hyperthermia
Leukopenia and/or agranulocytosis and convulsive seizures reported but infrequent; in schizophrenic patients with epilepsy, anticonvulsant medication should be maintained during treatment
Pigmentary retinopathy, which has been observed primarily in patients taking larger than recommended doses, is characterized by diminution of visual acuity, brownish coloring of vision, and impairment of night vision; examination of the fundus discloses deposits of pigment; the possibility of this complication may be reduced by remaining within recommended limits of dosage
Where patients are participating in activities requiring complete mental alertness (eg, driving) it is advisable to administer the phenothiazines cautiously and to increase the dosage gradually
Female patients appear to have a greater tendency to orthostatic hypotension than male patients; administration of epinephrine should be avoided in treatment of drug-induced hypotension as it may induce a reversed epinephrine effect on occasion; should a vasoconstrictor be required, the most suitable are levarterenol and phenylephrine
An increase in mammary neoplasms has been found in rodents after chronic administration of neuroleptic drugs; neither clinical studies nor epidemiologic studies conducted to date have shown an association between chronic administration of these drugs and mammary tumorigenesis; the available evidence is considered too limited to be conclusive at this time
Prolactin
- Antipsychotic drugs elevate prolactin levels; the elevation persists during chronic administration; tissue culture experiments indicate that approximately one-third of human breast cancers are prolactin dependent in vitro, a factor of potential importance if the prescription of these drugs is contemplated in a patient with a previously detected breast cancer
- Although disturbances such as galactorrhea, amenorrhea, gynecomastia, and impotence have been reported, the clinical significance of elevated serum prolactin levels is unknown for most patients
Proarrhythmic effects
- Certain factors may increase risk of Torsades de pointes and/or sudden death in association with the use of drugs that prolong the QTc interval, including bradycardia, hypokalemia, concomitant use of other drugs that prolong the QTc interval, presence of congenital prolongation of the QT interval, and for thioridazine in particular, its use in patients with reduced activity of P450 2D6 or its coadministration with drugs that may inhibit P450 2D6 or by some other mechanism interfere with the clearance of thioridazine
- Patients being considered for thioridazine treatment should have baseline ECG performed and serum potassium levels measured; serum potassium should be normalized before initiating treatment and patients with a QTc interval > 450 msec should not receive the therapy; may also be useful to periodically monitor ECG’s and serum potassium during thioridazine treatment, especially during a period of dose adjustment; therapy should be discontinued in patients who are found to have a QTc interval over 500 msec
- Patients receiving therapy who experience symptoms that may be associated with occurrence of Torsades de pointes (eg, dizziness, palpitations, or syncope) may warrant further cardiac evaluation; in particular, Holter monitoring should be considered
Tardive dyskinesia
- Tardive dyskinesia, a syndrome consisting of potentially irreversible, involuntary, dyskinetic movements may develop in patients treated with antipsychotic drugs; it is impossible to rely upon prevalence estimates to predict, at inception of antipsychotic treatment, which patients are likely to develop the syndrome; whether antipsychotic drug products differ in their potential to cause tardive dyskinesia is unknown
- The risk of developing the syndrome and likelihood that it will become irreversible are believed to increase as the duration of treatment and the total cumulative dose of antipsychotic drugs administered to the patient increase; syndrome can develop, although much less commonly, after relatively brief treatment periods at low doses
- There is no known treatment for established cases of tardive dyskinesia, although the syndrome may remit, partially or completely, if antipsychotic treatment is withdrawn; antipsychotic treatment itself, however, may suppress (or partially suppress) signs and symptoms of syndrome and thereby may possibly mask underlying disease process; effect that symptomatic suppression has upon long-term course of syndrome is unknown
- Given these considerations, antipsychotics should be prescribed in a manner that is most likely to minimize occurrence of tardive dyskinesia; chronic antipsychotic treatment should generally be reserved for patients who suffer from chronic illness that, is known to respond to antipsychotic drugs and for whom alternative, equally effective, but potentially less harmful treatments are not available or appropriate
- In patients who do require chronic treatment, the smallest dose and shortest duration of treatment producing a satisfactory clinical response should be sought; the need for continued treatment should be reassessed periodically
- If signs and symptoms of tardive dyskinesia appear in a patient on antipsychotics, drug discontinuation should be considered. However, some patients may require treatment despite the presence of the syndrome
- It has been suggested that people who have demonstrated a hypersensitivity reaction (eg, blood dyscrasias, jaundice) to one may be more prone to demonstrate a reaction to others; physicians should carefully consider benefit versus risk when treating less severe disorders
Neuroleptic malignant syndrome
- A potentially fatal symptom complex sometimes referred to as neuroleptic malignant syndrome (NMS) has been reported in association with antipsychotic drugs; clinical manifestations of NMS are hyperpyrexia, muscle rigidity, altered mental status, and evidence of autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis, and cardiac dysrhythmias)
- The diagnostic evaluation of patients with this syndrome is complicated; in arriving at a diagnosis, it is important to identify cases where clinical presentation includes both serious medical illness (eg, pneumonia, systemic infection, etc.) and untreated or inadequately treated extrapyramidal signs and symptoms (EPS); other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever, and primary central nervous system (CNS) pathology
- Management of NMS should include, immediate discontinuation of antipsychotic drugs and other drugs not essential to concurrent therapy, intensive symptomatic treatment and medical monitoring, and treatment of any concomitant serious medical problems for which specific treatments are available; there is no general agreement about specific pharmacological treatment regimens for uncomplicated NMS
- If patient requires antipsychotic drug treatment after recovery from NMS, potential reintroduction of drug therapy should be carefully considered; the patient should be carefully monitored, since recurrences of NMS have been reported
Drug interaction overview
- Drugs that inhibit cytochrome P450 2D6 isozyme activity (eg, fluoxetine and paroxetine), and certain other drugs (eg, fluvoxamine, propranolol, and pindolol) appear to appreciably inhibit metabolism of this drug; the resulting elevated levels of the drug would be expected to augment the prolongation of the QTc interval associated with thioridazine and may increase risk of serious, potentially fatal, cardiac arrhythmias, such as Torsades de pointes type arrhythmias
- Such an increased risk may result also from additive effect of coadministering this drug with other agents that prolong the QTc interval; therefore, thioridazine is contraindicated with these drugs as well as in patients, comprising about 7% of the normal population, who are known to have a genetic defect leading to reduced levels of activity of P450 2D6
Pregnancy & Lactation
Pregnancy
Use during pregnancy only if potential benefit justifies potential risk to fetus
Neonates exposed to antipsychotic drugs, during third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery; there have been reports of agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress and feeding disorder; these complications have varied in severity; while in some cases symptoms have been self-limited, in other cases neonates have required intensive care unit support and prolonged hospitalization
Lactation
Not known whether the drug is present in the milk; infants exposed to antipsychotic agents should be monitored for signs of adverse effects; routine monitoring of infant serum concentrations not recommended
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Piperazine phenothiazine agent; antagonist for the postsynaptic mesolimbic dopaminergic D2 receptors in the brain; decreases the release of hypothalamic and hypophyseal hormones
Pharmacokinetics
Half-Life elimination: 24 hr
Metabolism: Hepatic P450 enzyme CYP2D6
Enzymes inhibited: CYP2D6
Protein bound: 95%
Duration: 4-5 days
Images
BRAND | FORM. | UNIT PRICE | PILL IMAGE |
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thioridazine oral - | 100 mg tablet | ![]() | |
thioridazine oral - | 25 mg tablet | ![]() | |
thioridazine oral - | 10 mg tablet | ![]() | |
thioridazine oral - | 50 mg tablet | ![]() | |
thioridazine oral - | 50 mg tablet | ![]() | |
thioridazine oral - | 25 mg tablet | ![]() | |
thioridazine oral - | 10 mg tablet | ![]() | |
thioridazine oral - | 100 mg tablet | ![]() |
Copyright © 2010 First DataBank, Inc.
Patient Handout
thioridazine oral
THIORIDAZINE - ORAL
(thigh-oh-RID-uh-zeen)
COMMON BRAND NAME(S): Mellaril
WARNING: Thioridazine rarely has caused very serious (possibly fatal) irregular heartbeat (QT prolongation in the EKG). It should be used only in patients who have not shown improvement with at least 2 other antipsychotic medications or who cannot tolerate other antipsychotic medications. This medication should not be used with other medications that can also cause a slow or irregular heartbeat. (See also Drug Interactions.)There may be a slightly increased risk of serious, possibly fatal side effects (such as heart failure, fast/irregular heartbeat, pneumonia) when this medication is used by older adults with dementia. This medication is not approved for the treatment of dementia-related behavior problems. Discuss the risks and benefits of this medication, as well as other effective and possibly safer treatments for dementia-related behavior problems, with the doctor.
USES: This medication is used to treat certain mental/mood disorders (such as schizophrenia). This medication helps you to think more clearly, feel less nervous, and take part in everyday life. It can also help prevent suicide in people likely to harm themselves and reduce aggression and the desire to hurt others. It can help decrease your negative thoughts and hallucinations. Thioridazine belongs to a class of drugs known as phenothiazines.
HOW TO USE: Take this medication by mouth with or without food as directed by your doctor, usually 2 to 4 times a day.Dosage is based on your medical condition and response to therapy. Once your condition improves and you are better for a while, your doctor may work with you to reduce your regular dose. This may be done over time. Do not stop your medication or lower your dose without talking with your doctor first. Some conditions may become worse when the drug is stopped abruptly. Your dose may need to be gradually reduced.Use this medication regularly in order to get the most benefit from it. To help you remember, use it at the same times each day.Tell your doctor if your condition lasts or gets worse.
SIDE EFFECTS: Dizziness, lightheadedness, drowsiness, difficulty urinating, constipation, restlessness, headache, and blurred vision may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Dizziness and lightheadedness can increase the risk of falling. Get up slowly when rising from a sitting or lying position.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if you have any serious side effects, including: shakiness (tremors), mask-like facial expression, jerking movements while walking, signs of infection (such as sore throat that doesn't go away, fever), vision changes (such as vision loss, sudden difficulty seeing at night, brown-tinged vision).Get medical help right away if you have any very serious side effects, including: severe dizziness, fainting, slow heartbeat, seizures.Thioridazine may rarely cause a condition known as tardive dyskinesia. In some cases this condition may be permanent. Tell your doctor right away if you develop any unusual/uncontrolled movements (especially of the face, lips, tongue, arms or legs).In rare cases, thioridazine may increase your level of a certain chemical made by the body (prolactin). For females, this increase in prolactin may result in unwanted breast milk, missed/stopped periods, or difficulty becoming pregnant. For males, it may result in decreased sexual ability, inability to produce sperm, or enlarged breasts. If you develop any of these symptoms, tell your doctor right away.This medication may rarely cause a very serious condition called neuroleptic malignant syndrome (NMS). Get medical help right away if you have any of the following symptoms: fever, muscle stiffness/pain/tenderness/weakness, severe tiredness, severe confusion, sweating, fast/irregular heartbeat, dark urine, signs of kidney problems (such as change in the amount of urine).A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
PRECAUTIONS: Before taking thioridazine, tell your doctor or pharmacist if you are allergic to it; or to other phenothiazines (such as chlorpromazine); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: nervous system problems (such as seizures, drug/alcohol overdose, severe drowsiness), blood pressure problems, certain blood problems (such as low white blood cell count), Parkinson's disease, low enzymes needed to remove drugs from the body (slow hydroxylator).Thioridazine may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using thioridazine, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using thioridazine safely.This drug may make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness.Older adults may be more sensitive to the side effects of this drug, especially dizziness, lightheadedness, drowsiness, confusion, constipation, difficulty urinating, and QT prolongation (see above). Dizziness, lightheadedness, drowsiness, and confusion can increase the risk of falling.During pregnancy, this medication should be used only when clearly needed. Babies born to mothers who have used this drug during the last 3 months of pregnancy may rarely develop symptoms including muscle stiffness or shakiness, drowsiness, feeding/breathing difficulties, or constant crying. If you notice any of these symptoms in your newborn especially during their first month, tell the doctor right away.Since untreated mental/mood problems (such as schizophrenia, depression) can be a serious condition, do not stop taking this medication unless directed by your doctor. If you are planning pregnancy, become pregnant, or think you may be pregnant, immediately discuss with your doctor the benefits and risks of using this medication during pregnancy.It is unknown if this drug passes into breast milk. Consult your doctor before breast-feeding.
DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug include: cabergoline, elacestrant, lithium, certain products used to treat chronic hepatitis C (asunaprevir, ombitasvir/paritaprevir/ritonavir), medications for Parkinson's disease (such as levodopa).Many drugs besides thioridazine may affect the heart rhythm (QT prolongation), including amiodarone, dofetilide, pimozide, procainamide, quinidine, sotalol, macrolide antibiotics (such as erythromycin), ziprasidone, among others. Before using thioridazine, report all medications you are currently using to your doctor or pharmacist.Other medications can affect the removal of thioridazine from your body, which may affect how thioridazine works. Examples include bupropion, cinacalcet, dacomitinib, duloxetine, mirabegron, pindolol, propranolol, rolapitant, terbinafine, certain SSRI antidepressants (such as fluoxetine, fluvoxamine, paroxetine), among others.Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.
OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.
NOTES: Do not share this medication with others.Lab and/or medical tests (such as eye exams, potassium levels, EKG) may be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.
MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.
STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Information last revised May 2023. Copyright(c) 2023 First Databank, Inc.
IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.
Formulary
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