chlorpheniramine/pseudoephedrine (OTC)

Rhinitis/Decongestant

Liquid: 10mL PO q4-6hr; not to exceed 60mL/24hr

Chewable tablet: 2 tabs PO q4-6hr; not to exceed 8 tabs/24hr

Tablet: 1 tab PO q4-6hr; not to exceed 4 tabs/24hr

Rhinitis/Decongestant

<6 Years Old

• Ask a pediatrician

6-12 Years Old

• Liquid drops: 2 mL PO q4-6hr; not to exceed 8 mL/24hr
• Liquid: 5 mL PO q4-6hr; not to exceed 30 mL/24hr
• Chewable tablet: Chlorpheniramine maleate 2 mg and pseudoephedrine HCl 30 mg PO q4-6hr
• Tablet: One half tablet PO q4-6hr; not to exceed 2 tabs/24hr

>12 Years Old

• Liquid: 10mL PO q4-6hr; not to exceed 60mL/24hr
• Chewable tablet: 2 tabs PO q4-6hr; not to exceed 8 tabs/24hr
• Tablet: Chlorpheniramine maleate 4 mg and pseudoephedrine HCl 60 mg PO q4-6hr

Contraindicated (15)

• dihydroergotamine

  dihydroergotamine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• dihydroergotamine inhaled

  dihydroergotamine inhaled increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• dihydroergotamine intranasal

  dihydroergotamine intranasal increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• ergoloid mesylates

  ergoloid mesylates increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• ergonovine

  ergonovine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• ergotamine

  ergotamine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• isocarboxazid

  isocarboxazid increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• linezolid

  linezolid increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• methylergonovine

  methylergonovine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• phenelzine

  phenelzine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• procarbazine

  procarbazine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• rasagiline

  rasagiline increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• selegiline

  selegiline increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• selegiline transdermal

  selegiline transdermal increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• tranylcypromine

  tranylcypromine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

Serious - Use Alternative (40)

• abametapir

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

• amitriptyline

  amitriptyline increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• amoxapine

  amoxapine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• apalutamide

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

• cabergoline

  cabergoline, pseudoephedrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.

• calcium/magnesium/potassium/sodium oxybates

  chlorpheniramine, 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.

• clomipramine

  clomipramine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• cocaine topical

  cocaine topical increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• desipramine

  desipramine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• desvenlafaxine

  desvenlafaxine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• doxapram

  doxapram increases effects of pseudoephedrine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Additive pressor effect.

• doxepin

  doxepin increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• duloxetine

  duloxetine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• eluxadoline

  chlorpheniramine, eluxadoline. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration with other drugs that cause constipation. Increases risk for constipation related serious adverse reactions.

• fexinidazole

  fexinidazole will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

• idelalisib

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

• imipramine

  imipramine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• iobenguane I 123

  pseudoephedrine decreases effects of iobenguane I 123 by receptor binding competition. Avoid or Use Alternate Drug. If clinically appropriate, discontinue drugs that compete for NE receptor sites for at least 5 half-lives; may cause false-negative imaging results. Do not administer pseudoephedrine until at least 7 days after each iobenguane dose.

• iobenguane I 131

  pseudoephedrine decreases effects of iobenguane I 131 by receptor binding competition. Avoid or Use Alternate Drug. If clinically appropriate, discontinue drugs that compete for NE receptor sites for at least 5 half-lives; may cause false-negative imaging results. Do not administer pseudoephedrine until at least 7 days after each iobenguane dose.

• isocarboxazid

  isocarboxazid increases effects of chlorpheniramine by Other (see comment). Avoid or Use Alternate Drug. Comment: Isocarboxazid should not be administered in combination with antihistamines because of potential additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .

• isoflurane

  isoflurane increases toxicity of pseudoephedrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.

• levomilnacipran

  levomilnacipran increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• lofepramine

  lofepramine, pseudoephedrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• lonafarnib

  lonafarnib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with sensitive CYP3A substrates. If coadministration unavoidable, monitor for adverse reactions and reduce CYP3A substrate dose in accordance with product labeling.

• maprotiline

  maprotiline, pseudoephedrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• methoxyflurane

  methoxyflurane increases toxicity of pseudoephedrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.

• metoclopramide intranasal

  chlorpheniramine, 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.

• milnacipran

  milnacipran increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• nortriptyline

  nortriptyline increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• olopatadine intranasal

  chlorpheniramine 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.

• ozanimod

  ozanimod increases toxicity of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Because the active metabolite of ozanimod inhibits MAO-B in vitro, there is a potential for serious adverse reactions, including hypertensive crisis. Therefore, coadministration of ozanimod with drugs that can increase norepinephrine or serotonin is not recommended. Monitor for hypertension with concomitant use.

• protriptyline

  protriptyline increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• sevoflurane

  sevoflurane increases toxicity of pseudoephedrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.

• sodium oxybate

  chlorpheniramine, 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.

• tranylcypromine

  tranylcypromine increases effects of chlorpheniramine by Other (see comment). Avoid or Use Alternate Drug. Comment: Tranylcypromine should not be administered in combination with antihistamines because of potential additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .

• trazodone

  trazodone, pseudoephedrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• trimipramine

  trimipramine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• tucatinib

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

• venlafaxine

  venlafaxine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• voxelotor

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

Monitor Closely (265)

• acetazolamide

  acetazolamide will increase the level or effect of pseudoephedrine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor.

• acrivastine

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

• albuterol

  chlorpheniramine increases and albuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  albuterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• alfentanil

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

• alfuzosin

  pseudoephedrine decreases effects of alfuzosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• alprazolam

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

• aluminum hydroxide

  aluminum hydroxide will increase the level or effect of pseudoephedrine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor. Caution advised with frequent or high dose antacids

• amifampridine

  chlorpheniramine 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.

• amisulpride

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

• amitriptyline

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

• ammonium chloride

  ammonium chloride decreases effects of pseudoephedrine by unknown mechanism. Use Caution/Monitor. Urinary excretion of indirect acting alpha/beta agonists (eg, pseudoephedrine) may increase when administered concomitantly with urinary acidifying agents, resulting in lower serum concentrations.

• amobarbital

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

• amoxapine

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

• apomorphine

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

• arformoterol

  chlorpheniramine increases and arformoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  arformoterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• aripiprazole

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

• benzphetamine

  benzphetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• armodafinil

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

• asenapine

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

• asenapine transdermal

  asenapine transdermal and chlorpheniramine both increase sedation. Use Caution/Monitor.

• azelastine

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

• baclofen

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

• belladonna and opium

  chlorpheniramine and belladonna and opium both increase sedation. Use Caution/Monitor.

• belzutifan

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

• benperidol

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

• benzphetamine

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

• brexanolone

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

• bromocriptine

  bromocriptine, pseudoephedrine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Hypertension, V tach.

• brompheniramine

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

• buprenorphine

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

• buprenorphine buccal

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

• butabarbital

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

• butalbital

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

• butorphanol

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

• caffeine

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

• carbinoxamine

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

• carisoprodol

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

• cenobamate

  cenobamate will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.
  
  cenobamate, chlorpheniramine. Either increases effects of the other by sedation. Use Caution/Monitor.

• chloral hydrate

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

• chlordiazepoxide

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

• chlorpromazine

  chlorpheniramine and chlorpromazine both increase sedation. Use Caution/Monitor.
  
  chlorpromazine, 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.

• chlorzoxazone

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

• dexfenfluramine

  dexfenfluramine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• cinnarizine

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

• clemastine

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

• clobazam

  chlorpheniramine, 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

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

• clonazepam

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

• clorazepate

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

• clozapine

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

• codeine

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

• crofelemer

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

• cyclizine

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

• cyclobenzaprine

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

• cyproheptadine

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

• dabrafenib

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

• dantrolene

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

• daridorexant

  chlorpheniramine 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.

• desflurane

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

• desipramine

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

• deutetrabenazine

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

• dexchlorpheniramine

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

• dexfenfluramine

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

• dexmedetomidine

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

• dexmethylphenidate

  dexmethylphenidate and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and dexmethylphenidate decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dextroamphetamine

  dextroamphetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and dextroamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dextromoramide

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

• diethylpropion

  diethylpropion and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• diamorphine

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

• diazepam

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

• diazepam intranasal

  diazepam intranasal, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration may potentiate the CNS-depressant effects of each drug.

• diethylpropion

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

• difelikefalin

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

• difenoxin hcl

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

• dimenhydrinate

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

• diphenhydramine

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

• diphenoxylate hcl

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

• dipipanone

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

• dobutamine

  chlorpheniramine increases and dobutamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dobutamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• donepezil transdermal

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

• dopamine

  dopamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• dopamine

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

• dopexamine

  dopexamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and dopexamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dosulepin

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

• doxazosin

  pseudoephedrine decreases effects of doxazosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• doxepin

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

• doxylamine

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

• droperidol

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

• droxidopa

  pseudoephedrine and droxidopa both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. May increase risk for supine hypertension

• efavirenz

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

• elagolix

  elagolix will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

• ephedrine

  ephedrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  ephedrine, pseudoephedrine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.
  
  chlorpheniramine increases and ephedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• epinephrine

  epinephrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• epinephrine inhaled

  pseudoephedrine, epinephrine inhaled. Either increases effects of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• epinephrine racemic

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

• epinephrine racemic

  epinephrine racemic and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• esketamine intranasal

  esketamine intranasal, chlorpheniramine. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely.
  
  esketamine intranasal, pseudoephedrine. Either increases toxicity of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Closely monitor blood pressure with concomitant use of esketamine nasal with stimulants. .

• estazolam

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

• fenfluramine

  fenfluramine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• ethanol

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

• etomidate

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

• fedratinib

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

• fenfluramine

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

• fentanyl

  fentanyl, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.

• fentanyl intranasal

  fentanyl intranasal, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.

• fentanyl transdermal

  fentanyl transdermal, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.

• fentanyl transmucosal

  fentanyl transmucosal, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.

• flibanserin

  chlorpheniramine and flibanserin both increase sedation. Modify Therapy/Monitor Closely. Risk for sedation increased if flibanserin is coadministration with other CNS depressants.

• fluphenazine

  chlorpheniramine and fluphenazine both increase sedation. Use Caution/Monitor.
  
  fluphenazine, 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.

• flurazepam

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

• formoterol

  formoterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• formoterol

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

• fosphenytoin

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

• gabapentin

  gabapentin, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.

• gabapentin enacarbil

  gabapentin enacarbil, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.

• ganaxolone

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

• glycopyrronium tosylate topical

  glycopyrronium tosylate topical, chlorpheniramine. 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.

• gotu kola

  gotu kola increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• haloperidol

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

• hawthorn

  hawthorn increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• hops

  hops increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• hyaluronidase

  chlorpheniramine decreases effects of hyaluronidase by Other (see comment). Use Caution/Monitor. Comment: Antihistamines, when given in large systemic doses, may render tissues partially resistant to the action of hyaluronidase. Patients may require larger amounts of hyaluronidase for equivalent dispersing effect.

• hydralazine

  hydralazine, pseudoephedrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• hydromorphone

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

• hydroxyzine

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

• iloperidone

  chlorpheniramine and iloperidone both increase sedation. Use Caution/Monitor.
  
  iloperidone increases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.

• imipramine

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

• insulin degludec

  pseudoephedrine decreases effects of insulin degludec by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• insulin degludec/insulin aspart

  pseudoephedrine decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• insulin detemir

  pseudoephedrine decreases effects of insulin detemir by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• insulin glargine

  pseudoephedrine decreases effects of insulin glargine by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• insulin inhaled

  pseudoephedrine decreases effects of insulin inhaled by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• insulin regular human

  pseudoephedrine decreases effects of insulin regular human by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• isoproterenol

  chlorpheniramine increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  isoproterenol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• istradefylline

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

• levalbuterol

  levalbuterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• kava

  kava increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• ketamine

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

• ketotifen, ophthalmic

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

• lasmiditan

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

• lenacapavir

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

• letermovir

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

• levalbuterol

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

• levorphanol

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

• lisdexamfetamine

  lisdexamfetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and lisdexamfetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• lofepramine

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

• metaproterenol

  metaproterenol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• lofexidine

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

• loprazolam

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

• lorazepam

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

• lormetazepam

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

• loxapine

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

• loxapine inhaled

  chlorpheniramine and loxapine inhaled both increase sedation. Use Caution/Monitor.

• lurasidone

  lurasidone, chlorpheniramine. 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

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

• marijuana

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

• melatonin

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

• meperidine

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

• meprobamate

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

• metaproterenol

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

• metaxalone

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

• methadone

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

• methamphetamine

  chlorpheniramine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  methamphetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• methenamine

  methenamine decreases effects of pseudoephedrine by unknown mechanism. Use Caution/Monitor. Urinary excretion of indirect acting alpha/beta agonists (eg, pseudoephedrine) may increase when administered concomitantly with urinary acidifying agents, resulting in lower serum concentrations.

• methocarbamol

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

• methyldopa

  methyldopa increases effects of pseudoephedrine by unknown mechanism. Use Caution/Monitor.

• methylenedioxymethamphetamine

  chlorpheniramine increases and methylenedioxymethamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  methylenedioxymethamphetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• midazolam

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

• midodrine

  midodrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• midazolam intranasal

  midazolam intranasal, chlorpheniramine. Either increases effects 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

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

• mirtazapine

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

• mitotane

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

• modafinil

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

• morphine

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

• motherwort

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

• moxonidine

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

• nabilone

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

• nalbuphine

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

• nateglinide

  pseudoephedrine decreases effects of nateglinide by pharmacodynamic antagonism. Use Caution/Monitor. Coadministration may reduce nateglinide's hypoglycemic action.

• norepinephrine

  norepinephrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• nortriptyline

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

• olodaterol inhaled

  pseudoephedrine and olodaterol inhaled both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Caution with coadministration of adrenergic drugs by any route because of additive sympathetic effects

• olanzapine

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

• opium tincture

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

• orphenadrine

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

• oxazepam

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

• oxycodone

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

• oxymorphone

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

• oxytocin

  oxytocin increases effects of pseudoephedrine by pharmacodynamic synergism. Use Caution/Monitor.

• paliperidone

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

• papaveretum

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

• papaverine

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

• passion flower

  passion flower increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• pentazocine

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

• pentobarbital

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

• perphenazine

  perphenazine, 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.
  
  chlorpheniramine and perphenazine both increase sedation. Use Caution/Monitor.

• phendimetrazine

  phendimetrazine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and phendimetrazine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenelzine

  phenelzine increases effects of chlorpheniramine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Coadministration of phenelzine and antihistamines may result in additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .

• phentermine

  phentermine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• phenobarbital

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

• phentermine

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

• phenylephrine

  phenylephrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenylephrine PO

  chlorpheniramine increases and phenylephrine PO decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. .
  
  phenylephrine PO and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• pholcodine

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

• pirbuterol

  pirbuterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• pimozide

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

• pirbuterol

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

• potassium phosphate

  potassium phosphate decreases effects of pseudoephedrine by unknown mechanism. Use Caution/Monitor. Urinary excretion of indirect acting alpha/beta agonists (eg, pseudoephedrine) may increase when administered concomitantly with urinary acidifying agents, resulting in lower serum concentrations.

• pregabalin

  pregabalin, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.

• primidone

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

• prochlorperazine

  chlorpheniramine and prochlorperazine both increase sedation. Use Caution/Monitor.
  
  prochlorperazine, 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.

• promazine

  promazine, pseudoephedrine. 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.

• promethazine

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

• promethazine

  promethazine, pseudoephedrine. 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.

• propofol

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

• propylhexedrine

  propylhexedrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and propylhexedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• protriptyline

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

• safinamide

  pseudoephedrine and safinamide both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Monitor patients for hypertension if safinamide is prescribed concomitantly with prescription or nonprescription sympathomimetics, including nasal, oral, or ophthalmic decongestants and cold remedies.

• quazepam

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

• quetiapine

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

• ramelteon

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

• risperidone

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

• rucaparib

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

• salmeterol

  chlorpheniramine increases and salmeterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  salmeterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• scullcap

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

• serdexmethylphenidate/dexmethylphenidate

  serdexmethylphenidate/dexmethylphenidate and pseudoephedrine both decrease sedation. Use Caution/Monitor.
  
  serdexmethylphenidate/dexmethylphenidate and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• secobarbital

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

• sevoflurane

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

• shepherd's purse

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

• silodosin

  pseudoephedrine decreases effects of silodosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• sodium bicarbonate

  sodium bicarbonate will increase the level or effect of pseudoephedrine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor. Caution advised with frequent or high dose antacids

• sodium citrate/citric acid

  sodium citrate/citric acid will increase the level or effect of pseudoephedrine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor.

• sodium lactate

  sodium lactate will increase the level or effect of pseudoephedrine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor.

• sodium phosphates, IV

  sodium phosphates, IV decreases effects of pseudoephedrine by unknown mechanism. Use Caution/Monitor. Urinary excretion of indirect acting alpha/beta agonists (eg, pseudoephedrine) may increase when administered concomitantly with urinary acidifying agents, resulting in lower serum concentrations.

• solriamfetol

  pseudoephedrine and solriamfetol both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• spironolactone

  spironolactone decreases effects of pseudoephedrine by pharmacodynamic antagonism. Use Caution/Monitor.

• stiripentol

  stiripentol, chlorpheniramine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.

• sufentanil

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

• tamsulosin

  pseudoephedrine decreases effects of tamsulosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• tapentadol

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

• tazemetostat

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

• tecovirimat

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

• temazepam

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

• terazosin

  pseudoephedrine decreases effects of terazosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• terbutaline

  chlorpheniramine increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  terbutaline and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• thioridazine

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

• thiothixene

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

• trifluoperazine

  trifluoperazine, 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.

• topiramate

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

• tramadol

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

• trazodone

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

• triazolam

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

• triclofos

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

• trifluoperazine

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

• trimipramine

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

• triprolidine

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

• valerian

  valerian increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• xylometazoline

  chlorpheniramine increases and xylometazoline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  pseudoephedrine and xylometazoline both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• yohimbine

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

• ziconotide

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

• ziprasidone

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

• zotepine

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

Minor (7)

• acetazolamide

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

• anastrozole

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

• ashwagandha

  ashwagandha increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. May enhance CNS depression.

• brimonidine

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

• cyclophosphamide

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

• desmopressin

  desmopressin increases effects of pseudoephedrine by pharmacodynamic synergism. Minor/Significance Unknown.

• eucalyptus

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

• abametapir

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

• acetazolamide

  Monitor Closely (1)acetazolamide will increase the level or effect of pseudoephedrine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor.Minor (1)acetazolamide will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• acrivastine

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

• albuterol

  Monitor Closely (2)chlorpheniramine increases and albuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  albuterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• alfentanil

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

• alfuzosin

  Monitor Closely (1)pseudoephedrine decreases effects of alfuzosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• alprazolam

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

• aluminum hydroxide

  Monitor Closely (1)aluminum hydroxide will increase the level or effect of pseudoephedrine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor. Caution advised with frequent or high dose antacids

• amifampridine

  Monitor Closely (1)chlorpheniramine 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.

• amisulpride

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

• amitriptyline

  Monitor Closely (1)chlorpheniramine and amitriptyline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)amitriptyline increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• ammonium chloride

  Monitor Closely (1)ammonium chloride decreases effects of pseudoephedrine by unknown mechanism. Use Caution/Monitor. Urinary excretion of indirect acting alpha/beta agonists (eg, pseudoephedrine) may increase when administered concomitantly with urinary acidifying agents, resulting in lower serum concentrations.

• amobarbital

  Monitor Closely (2)amobarbital will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  chlorpheniramine and amobarbital both increase sedation. Use Caution/Monitor.

• amoxapine

  Monitor Closely (1)chlorpheniramine and amoxapine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)amoxapine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• anastrozole

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

• apalutamide

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

• apomorphine

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

• arformoterol

  Monitor Closely (2)chlorpheniramine increases and arformoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  arformoterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• aripiprazole

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

• armodafinil

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

• asenapine

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

• asenapine transdermal

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

• ashwagandha

  Minor (1)ashwagandha increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. May enhance CNS depression.

• azelastine

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

• baclofen

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

• belladonna and opium

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

• belzutifan

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

• benperidol

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

• benzphetamine

  Monitor Closely (2)benzphetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and benzphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• brexanolone

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

• brimonidine

  Minor (1)brimonidine increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. Increased CNS depression.

• bromocriptine

  Monitor Closely (1)bromocriptine, pseudoephedrine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Hypertension, V tach.

• brompheniramine

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

• buprenorphine

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

• buprenorphine buccal

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

• butabarbital

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

• butalbital

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

• butorphanol

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

• cabergoline

  Serious - Use Alternative (1)cabergoline, pseudoephedrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.

• caffeine

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

• calcium/magnesium/potassium/sodium oxybates

  Serious - Use Alternative (1)chlorpheniramine, 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.

• carbinoxamine

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

• carisoprodol

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

• cenobamate

  Monitor Closely (2)cenobamate, chlorpheniramine. Either increases effects of the other by sedation. Use Caution/Monitor.
  
  cenobamate will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.

• chloral hydrate

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

• chlordiazepoxide

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

• chlorpromazine

  Monitor Closely (2)chlorpheniramine and chlorpromazine both increase sedation. Use Caution/Monitor.
  
  chlorpromazine, 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.

• chlorzoxazone

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

• cinnarizine

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

• clemastine

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

• clobazam

  Monitor Closely (1)chlorpheniramine, 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

  Monitor Closely (1)chlorpheniramine and clomipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)clomipramine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• clonazepam

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

• clorazepate

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

• clozapine

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

• cocaine topical

  Serious - Use Alternative (1)cocaine topical increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• codeine

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

• crofelemer

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

• cyclizine

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

• cyclobenzaprine

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

• cyclophosphamide

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

• cyproheptadine

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

• dabrafenib

  Monitor Closely (1)dabrafenib will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• dantrolene

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

• daridorexant

  Monitor Closely (1)chlorpheniramine 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.

• desflurane

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

• desipramine

  Monitor Closely (1)chlorpheniramine and desipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)desipramine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• desmopressin

  Minor (1)desmopressin increases effects of pseudoephedrine by pharmacodynamic synergism. Minor/Significance Unknown.

• desvenlafaxine

  Serious - Use Alternative (1)desvenlafaxine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• deutetrabenazine

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

• dexchlorpheniramine

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

• dexfenfluramine

  Monitor Closely (2)chlorpheniramine increases and dexfenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dexfenfluramine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• dexmedetomidine

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

• dexmethylphenidate

  Monitor Closely (2)dexmethylphenidate and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and dexmethylphenidate decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dextroamphetamine

  Monitor Closely (2)dextroamphetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and dextroamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dextromoramide

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

• diamorphine

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

• diazepam

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

• diazepam intranasal

  Monitor Closely (1)diazepam intranasal, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration may potentiate the CNS-depressant effects of each drug.

• diethylpropion

  Monitor Closely (2)chlorpheniramine increases and diethylpropion decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  diethylpropion and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• difelikefalin

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

• difenoxin hcl

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

• dihydroergotamine

  Contraindicated (1)dihydroergotamine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• dihydroergotamine inhaled

  Contraindicated (1)dihydroergotamine inhaled increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• dihydroergotamine intranasal

  Contraindicated (1)dihydroergotamine intranasal increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• dimenhydrinate

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

• diphenhydramine

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

• diphenoxylate hcl

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

• dipipanone

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

• dobutamine

  Monitor Closely (2)chlorpheniramine increases and dobutamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dobutamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• donepezil transdermal

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

• dopamine

  Monitor Closely (2)dopamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and dopamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dopexamine

  Monitor Closely (2)dopexamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and dopexamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dosulepin

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

• doxapram

  Serious - Use Alternative (1)doxapram increases effects of pseudoephedrine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Additive pressor effect.

• doxazosin

  Monitor Closely (1)pseudoephedrine decreases effects of doxazosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• doxepin

  Monitor Closely (1)chlorpheniramine and doxepin both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)doxepin increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• doxylamine

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

• droperidol

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

• droxidopa

  Monitor Closely (1)pseudoephedrine and droxidopa both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. May increase risk for supine hypertension

• duloxetine

  Serious - Use Alternative (1)duloxetine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• efavirenz

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

• elagolix

  Monitor Closely (1)elagolix will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.

• eluxadoline

  Serious - Use Alternative (1)chlorpheniramine, eluxadoline. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration with other drugs that cause constipation. Increases risk for constipation related serious adverse reactions.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  Monitor Closely (1)elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

• ephedrine

  Monitor Closely (3)ephedrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and ephedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  ephedrine, pseudoephedrine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.

• epinephrine

  Monitor Closely (2)epinephrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• epinephrine inhaled

  Monitor Closely (1)pseudoephedrine, epinephrine inhaled. Either increases effects of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• epinephrine racemic

  Monitor Closely (2)chlorpheniramine increases and epinephrine racemic decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  epinephrine racemic and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• ergoloid mesylates

  Contraindicated (1)ergoloid mesylates increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• ergonovine

  Contraindicated (1)ergonovine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• ergotamine

  Contraindicated (1)ergotamine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• esketamine intranasal

  Monitor Closely (2)esketamine intranasal, chlorpheniramine. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely.
  
  esketamine intranasal, pseudoephedrine. Either increases toxicity of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Closely monitor blood pressure with concomitant use of esketamine nasal with stimulants. .

• estazolam

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

• ethanol

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

• etomidate

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

• eucalyptus

  Minor (1)chlorpheniramine and eucalyptus both increase sedation. Minor/Significance Unknown.

• fedratinib

  Monitor Closely (1)fedratinib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.

• fenfluramine

  Monitor Closely (2)fenfluramine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and fenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• fentanyl

  Monitor Closely (1)fentanyl, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.

• fentanyl intranasal

  Monitor Closely (1)fentanyl intranasal, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.

• fentanyl transdermal

  Monitor Closely (1)fentanyl transdermal, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.

• fentanyl transmucosal

  Monitor Closely (1)fentanyl transmucosal, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.

• fexinidazole

  Serious - Use Alternative (1)fexinidazole will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

• flibanserin

  Monitor Closely (1)chlorpheniramine and flibanserin both increase sedation. Modify Therapy/Monitor Closely. Risk for sedation increased if flibanserin is coadministration with other CNS depressants.

• fluphenazine

  Monitor Closely (2)chlorpheniramine and fluphenazine both increase sedation. Use Caution/Monitor.
  
  fluphenazine, 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.

• flurazepam

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

• formoterol

  Monitor Closely (2)chlorpheniramine increases and formoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  formoterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• fosphenytoin

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

• gabapentin

  Monitor Closely (1)gabapentin, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.

• gabapentin enacarbil

  Monitor Closely (1)gabapentin enacarbil, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.

• ganaxolone

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

• glycopyrronium tosylate topical

  Monitor Closely (1)glycopyrronium tosylate topical, chlorpheniramine. 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.

• gotu kola

  Monitor Closely (1)gotu kola increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• haloperidol

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

• hawthorn

  Monitor Closely (1)hawthorn increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• hops

  Monitor Closely (1)hops increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• hyaluronidase

  Monitor Closely (1)chlorpheniramine decreases effects of hyaluronidase by Other (see comment). Use Caution/Monitor. Comment: Antihistamines, when given in large systemic doses, may render tissues partially resistant to the action of hyaluronidase. Patients may require larger amounts of hyaluronidase for equivalent dispersing effect.

• hydralazine

  Monitor Closely (1)hydralazine, pseudoephedrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.

• hydromorphone

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

• hydroxyzine

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

• idelalisib

  Serious - Use Alternative (1)idelalisib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates

• iloperidone

  Monitor Closely (2)chlorpheniramine and iloperidone both increase sedation. Use Caution/Monitor.
  
  iloperidone increases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.

• imipramine

  Monitor Closely (1)chlorpheniramine and imipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)imipramine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• insulin degludec

  Monitor Closely (1)pseudoephedrine decreases effects of insulin degludec by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• insulin degludec/insulin aspart

  Monitor Closely (1)pseudoephedrine decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• insulin detemir

  Monitor Closely (1)pseudoephedrine decreases effects of insulin detemir by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• insulin glargine

  Monitor Closely (1)pseudoephedrine decreases effects of insulin glargine by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• insulin inhaled

  Monitor Closely (1)pseudoephedrine decreases effects of insulin inhaled by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• insulin regular human

  Monitor Closely (1)pseudoephedrine decreases effects of insulin regular human by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.

• iobenguane I 123

  Serious - Use Alternative (1)pseudoephedrine decreases effects of iobenguane I 123 by receptor binding competition. Avoid or Use Alternate Drug. If clinically appropriate, discontinue drugs that compete for NE receptor sites for at least 5 half-lives; may cause false-negative imaging results. Do not administer pseudoephedrine until at least 7 days after each iobenguane dose.

• iobenguane I 131

  Serious - Use Alternative (1)pseudoephedrine decreases effects of iobenguane I 131 by receptor binding competition. Avoid or Use Alternate Drug. If clinically appropriate, discontinue drugs that compete for NE receptor sites for at least 5 half-lives; may cause false-negative imaging results. Do not administer pseudoephedrine until at least 7 days after each iobenguane dose.

• isocarboxazid

  Contraindicated (1)isocarboxazid increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.Serious - Use Alternative (1)isocarboxazid increases effects of chlorpheniramine by Other (see comment). Avoid or Use Alternate Drug. Comment: Isocarboxazid should not be administered in combination with antihistamines because of potential additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .

• isoflurane

  Serious - Use Alternative (1)isoflurane increases toxicity of pseudoephedrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.

• isoproterenol

  Monitor Closely (2)chlorpheniramine increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  isoproterenol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• istradefylline

  Monitor Closely (1)istradefylline will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.

• kava

  Monitor Closely (1)kava increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• ketamine

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

• ketotifen, ophthalmic

  Monitor Closely (1)chlorpheniramine and ketotifen, ophthalmic both increase sedation. Use Caution/Monitor.

• larotrectinib

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

• lasmiditan

  Monitor Closely (1)lasmiditan, chlorpheniramine. 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

  Monitor Closely (1)lemborexant, chlorpheniramine. Either increases effects of the other by sedation. Modify Therapy/Monitor Closely. Dosage adjustment may be necessary if lemborexant is coadministered with other CNS depressants because of potentially additive effects.

• lenacapavir

  Monitor Closely (1)lenacapavir will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir (a moderate CYP3A4 inhibitor) may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.

• letermovir

  Monitor Closely (1)letermovir increases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• levalbuterol

  Monitor Closely (2)levalbuterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and levalbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• levoketoconazole

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

• levomilnacipran

  Serious - Use Alternative (1)levomilnacipran increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• levorphanol

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

• linezolid

  Contraindicated (1)linezolid increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• lisdexamfetamine

  Monitor Closely (2)lisdexamfetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and lisdexamfetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• lofepramine

  Monitor Closely (1)chlorpheniramine and lofepramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)lofepramine, pseudoephedrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• lofexidine

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

• lonafarnib

  Serious - Use Alternative (1)lonafarnib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with sensitive CYP3A substrates. If coadministration unavoidable, monitor for adverse reactions and reduce CYP3A substrate dose in accordance with product labeling.

• loprazolam

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

• lorazepam

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

• lormetazepam

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

• loxapine

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

• loxapine inhaled

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

• lurasidone

  Monitor Closely (1)lurasidone, chlorpheniramine. 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

  Monitor Closely (1)chlorpheniramine and maprotiline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)maprotiline, pseudoephedrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• marijuana

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

• melatonin

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

• meperidine

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

• meprobamate

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

• metaproterenol

  Monitor Closely (2)metaproterenol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and metaproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• metaxalone

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

• methadone

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

• methamphetamine

  Monitor Closely (2)chlorpheniramine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  methamphetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• methenamine

  Monitor Closely (1)methenamine decreases effects of pseudoephedrine by unknown mechanism. Use Caution/Monitor. Urinary excretion of indirect acting alpha/beta agonists (eg, pseudoephedrine) may increase when administered concomitantly with urinary acidifying agents, resulting in lower serum concentrations.

• methocarbamol

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

• methoxyflurane

  Serious - Use Alternative (1)methoxyflurane increases toxicity of pseudoephedrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.

• methyldopa

  Monitor Closely (1)methyldopa increases effects of pseudoephedrine by unknown mechanism. Use Caution/Monitor.

• methylenedioxymethamphetamine

  Monitor Closely (2)chlorpheniramine increases and methylenedioxymethamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  methylenedioxymethamphetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• methylergonovine

  Contraindicated (1)methylergonovine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Ergot derivatives may enhance the vasoconstricting effect of pseudoephedrine and eventually significantly increasing blood pressure.

• metoclopramide intranasal

  Serious - Use Alternative (1)chlorpheniramine, 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.

• midazolam

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

• midazolam intranasal

  Monitor Closely (1)midazolam intranasal, chlorpheniramine. Either increases effects 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

  Monitor Closely (2)midodrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and midodrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• milnacipran

  Serious - Use Alternative (1)milnacipran increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• mirtazapine

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

• mitotane

  Monitor Closely (1)mitotane decreases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.

• modafinil

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

• morphine

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

• motherwort

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

• moxonidine

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

• nabilone

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

• nalbuphine

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

• nateglinide

  Monitor Closely (1)pseudoephedrine decreases effects of nateglinide by pharmacodynamic antagonism. Use Caution/Monitor. Coadministration may reduce nateglinide's hypoglycemic action.

• nettle

  Minor (1)nettle increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. (High dose nettle; theoretical interaction) May enhance CNS depression.

• norepinephrine

  Monitor Closely (2)norepinephrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• nortriptyline

  Monitor Closely (1)chlorpheniramine and nortriptyline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)nortriptyline increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• olanzapine

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

• olodaterol inhaled

  Monitor Closely (1)pseudoephedrine and olodaterol inhaled both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Caution with coadministration of adrenergic drugs by any route because of additive sympathetic effects

• olopatadine intranasal

  Serious - Use Alternative (1)chlorpheniramine 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.

• opium tincture

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

• orphenadrine

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

• oxazepam

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

• oxycodone

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

• oxymorphone

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

• oxytocin

  Monitor Closely (1)oxytocin increases effects of pseudoephedrine by pharmacodynamic synergism. Use Caution/Monitor.

• ozanimod

  Serious - Use Alternative (1)ozanimod increases toxicity of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Because the active metabolite of ozanimod inhibits MAO-B in vitro, there is a potential for serious adverse reactions, including hypertensive crisis. Therefore, coadministration of ozanimod with drugs that can increase norepinephrine or serotonin is not recommended. Monitor for hypertension with concomitant use.

• paliperidone

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

• papaveretum

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

• papaverine

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

• passion flower

  Monitor Closely (1)passion flower increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• pentazocine

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

• pentobarbital

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

• perphenazine

  Monitor Closely (2)perphenazine, 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.
  
  chlorpheniramine and perphenazine both increase sedation. Use Caution/Monitor.

• phendimetrazine

  Monitor Closely (2)phendimetrazine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and phendimetrazine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenelzine

  Contraindicated (1)phenelzine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.Monitor Closely (1)phenelzine increases effects of chlorpheniramine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Coadministration of phenelzine and antihistamines may result in additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .

• phenobarbital

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

• phentermine

  Monitor Closely (2)phentermine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenylephrine

  Monitor Closely (2)phenylephrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenylephrine PO

  Monitor Closely (2)chlorpheniramine increases and phenylephrine PO decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. .
  
  phenylephrine PO and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• pholcodine

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

• pimozide

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

• pirbuterol

  Monitor Closely (2)pirbuterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and pirbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• potassium phosphate

  Monitor Closely (1)potassium phosphate decreases effects of pseudoephedrine by unknown mechanism. Use Caution/Monitor. Urinary excretion of indirect acting alpha/beta agonists (eg, pseudoephedrine) may increase when administered concomitantly with urinary acidifying agents, resulting in lower serum concentrations.

• pregabalin

  Monitor Closely (1)pregabalin, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.

• primidone

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

• procarbazine

  Contraindicated (1)procarbazine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• prochlorperazine

  Monitor Closely (2)chlorpheniramine and prochlorperazine both increase sedation. Use Caution/Monitor.
  
  prochlorperazine, 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.

• promazine

  Monitor Closely (1)promazine, pseudoephedrine. 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.

• promethazine

  Monitor Closely (2)chlorpheniramine and promethazine both increase sedation. Use Caution/Monitor.
  
  promethazine, pseudoephedrine. 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.

• propofol

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

• propylhexedrine

  Monitor Closely (2)propylhexedrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  chlorpheniramine increases and propylhexedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• protriptyline

  Monitor Closely (1)chlorpheniramine and protriptyline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)protriptyline increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• quazepam

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

• quetiapine

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

• ramelteon

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

• rasagiline

  Contraindicated (1)rasagiline increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• ribociclib

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

• risperidone

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

• rucaparib

  Monitor Closely (1)rucaparib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.

• safinamide

  Monitor Closely (1)pseudoephedrine and safinamide both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Monitor patients for hypertension if safinamide is prescribed concomitantly with prescription or nonprescription sympathomimetics, including nasal, oral, or ophthalmic decongestants and cold remedies.

• sage

  Minor (1)chlorpheniramine and sage both increase sedation. Minor/Significance Unknown.

• salmeterol

  Monitor Closely (2)chlorpheniramine increases and salmeterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  salmeterol and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• scullcap

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

• secobarbital

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

• selegiline

  Contraindicated (1)selegiline increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• selegiline transdermal

  Contraindicated (1)selegiline transdermal increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

• serdexmethylphenidate/dexmethylphenidate

  Monitor Closely (2)serdexmethylphenidate/dexmethylphenidate and pseudoephedrine both decrease sedation. Use Caution/Monitor.
  
  serdexmethylphenidate/dexmethylphenidate and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• sevoflurane

  Monitor Closely (1)sevoflurane and chlorpheniramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)sevoflurane increases toxicity of pseudoephedrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.

• shepherd's purse

  Monitor Closely (1)chlorpheniramine and shepherd's purse both increase sedation. Use Caution/Monitor.

• Siberian ginseng

  Minor (1)Siberian ginseng increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. May enhance CNS depression.

• silodosin

  Monitor Closely (1)pseudoephedrine decreases effects of silodosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• sodium bicarbonate

  Monitor Closely (1)sodium bicarbonate will increase the level or effect of pseudoephedrine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor. Caution advised with frequent or high dose antacids

• sodium citrate/citric acid

  Monitor Closely (1)sodium citrate/citric acid will increase the level or effect of pseudoephedrine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor.

• sodium lactate

  Monitor Closely (1)sodium lactate will increase the level or effect of pseudoephedrine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor.

• sodium oxybate

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

• sodium phosphates, IV

  Monitor Closely (1)sodium phosphates, IV decreases effects of pseudoephedrine by unknown mechanism. Use Caution/Monitor. Urinary excretion of indirect acting alpha/beta agonists (eg, pseudoephedrine) may increase when administered concomitantly with urinary acidifying agents, resulting in lower serum concentrations.

• solriamfetol

  Monitor Closely (1)pseudoephedrine and solriamfetol both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• spironolactone

  Monitor Closely (1)spironolactone decreases effects of pseudoephedrine by pharmacodynamic antagonism. Use Caution/Monitor.

• stiripentol

  Monitor Closely (1)stiripentol, chlorpheniramine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.

• sufentanil

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

• tamsulosin

  Monitor Closely (1)pseudoephedrine decreases effects of tamsulosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• tapentadol

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

• tazemetostat

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

• tecovirimat

  Monitor Closely (1)tecovirimat will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.

• temazepam

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

• terazosin

  Monitor Closely (1)pseudoephedrine decreases effects of terazosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• terbutaline

  Monitor Closely (2)chlorpheniramine increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  terbutaline and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• thioridazine

  Monitor Closely (2)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.
  
  chlorpheniramine and thioridazine both increase sedation. Use Caution/Monitor.

• thiothixene

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

• topiramate

  Monitor Closely (1)chlorpheniramine and topiramate both increase sedation. Modify Therapy/Monitor Closely.

• tramadol

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

• tranylcypromine

  Contraindicated (1)tranylcypromine increases effects of pseudoephedrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.Serious - Use Alternative (1)tranylcypromine increases effects of chlorpheniramine by Other (see comment). Avoid or Use Alternate Drug. Comment: Tranylcypromine should not be administered in combination with antihistamines because of potential additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .

• trazodone

  Monitor Closely (1)chlorpheniramine and trazodone both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)trazodone, pseudoephedrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• triazolam

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

• triclofos

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

• trifluoperazine

  Monitor Closely (2)chlorpheniramine and trifluoperazine both increase sedation. Use Caution/Monitor.
  
  trifluoperazine, 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.

• trimipramine

  Monitor Closely (1)chlorpheniramine and trimipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)trimipramine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.

• triprolidine

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

• tucatinib

  Serious - Use Alternative (1)tucatinib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.

• valerian

  Monitor Closely (1)valerian increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• venlafaxine

  Serious - Use Alternative (1)venlafaxine increases effects of pseudoephedrine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug.

• voxelotor

  Serious - Use Alternative (1)voxelotor will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.

• xylometazoline

  Monitor Closely (2)chlorpheniramine increases and xylometazoline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  pseudoephedrine and xylometazoline both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• yohimbine

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

• ziconotide

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

• ziprasidone

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

• zotepine

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