chlorpheniramine (OTC)

Brand and Other Names:ChlorTrimeton, Diabetic Tussin
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Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

tablet

  • 4mg
  • 8mg
  • 12mg

syrup

  • 2mg/5mL

Allergic Rhinitis

Tablets or syrup: 4 mg PO q4-6hr; not to exceed 24 mg/day

Extended-release tablets: 8 mg PO q8-12hr or 12 mg q12hr; not to exceed 24 mg/day

Extended-release capsules: 12 mg PO qDay; not to exceed 24 mg/day

Sustained-release capsules: 8-12 mg PO q8-12hr, up to 16-24 mg/day

Additional Information

See also combo with hydrocodone (Tussionex)

Other Indications & Uses

Perennial & seasonal allergic & vasomotor rhinitis, relief of symptoms from colds, urticaria, angioedema, anaphylactic reactions, pruritus, allergic conjunctivitis

Dosage Forms & Strengths

tablet

  • 4mg
  • 8mg
  • 12mg

suspension

  • 2mg/mL

syrup

  • 2mg/5mL

Allergic Rhinitis

<2 years: Safety & efficacy not established

2-6 years: 1 mg PO q4-6hr; not to exceed 6 mg/day

6-12 years: 2 mg PO q4-6hr; not to exceed 12 mg/day or sustained release HS

>12 years

  • Tablets or syrup: 4 mg PO q4-6hr; not to exceed 24 mg/day
  • Extended-release tablets: 8 mg PO q8-12hr or 12 mg q12hr; not to exceed 24 mg/day
  • Extended-release capsules: 12 mg PO qDay; not to exceed 24 mg/day
  • Sustained-release capsules: 8-12 mg PO q8-12hr, up to 16-24 mg/day

4 mg PO qDay or q12hr

Sustained-release: 8 mg PO qHS

Nonanticholinergic antihistamines should be considered first when treating allergic reactions (Beers Criteria)

Avoid use in elderly because of high incidence of anticholinergic effects

Clearance reduced with advanced age, greater risk of confusion, dry mouth, constipation, and other anticholinergic effects and toxicity

May exacerbate existing lower urinary conditions or benign prostatic hyperplasia

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Interactions

Interaction Checker

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              Serious - Use Alternative (13)

              • 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.

              • 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.

              • 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.

              • 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

              • 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. .

              • 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.

              • 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.

              • 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. .

              • 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.

              • 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 (209)

              • albuterol

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

              • alfentanil

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

              • alprazolam

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

              • 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.

              • amitriptyline

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

              • 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.

              • aripiprazole

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

              • armodafinil

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

              • 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.

              • chlorzoxazone

                chlorpheniramine and chlorzoxazone both increase sedation. 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.

              • 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

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

              • dextroamphetamine

                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.

              • 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.

              • 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.

              • dopamine

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

              • dopexamine

                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.

              • 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.

              • 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

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

              • epinephrine

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

              • epinephrine racemic

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

              • esketamine intranasal

                esketamine intranasal, chlorpheniramine. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely.

              • estazolam

                chlorpheniramine and estazolam both increase sedation. 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.

              • flurazepam

                chlorpheniramine and flurazepam both increase sedation. 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.

              • 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.

              • 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.

              • isoproterenol

                chlorpheniramine increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. 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.

              • 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.

              • 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

                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.

              • 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.

              • methocarbamol

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

              • methylenedioxymethamphetamine

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

              • midazolam

                chlorpheniramine and midazolam both increase sedation. 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.

              • norepinephrine

                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.

              • 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.

              • 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

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

              • phendimetrazine

                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. .

              • 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

                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. .

              • pholcodine

                chlorpheniramine and pholcodine both increase sedation. 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.

              • 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.

              • promethazine

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

              • propofol

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

              • propylhexedrine

                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.

              • 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.

              • scullcap

                chlorpheniramine and scullcap both increase sedation. 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.

              • 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.

              • 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.

              • terbutaline

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

              • thioridazine

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

              • thiothixene

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

              • 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.

              • 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)

              • 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.

              • eucalyptus

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

              • nettle

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

              • ribociclib

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

              • sage

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

              • Siberian ginseng

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

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              Adverse Effects

              Varies in incidence & severity with the individual drug; also individual patients vary in susceptibility

              Frequency Not Defined

              CNS depression

              Drowsiness

              Sedation ranging from mild drowsiness to deep sleep (most frequent)

              Dizziness

              Lassitude

              Disturbed coordination

              Muscular weakness

              Restlessness, insomnia, tremors, euphoria, nervousness, delirium, palpitation, seizures is less common

              Epigastric distress

              Anorexia

              Nausea

              Vomiting

              Diarrhea

              Constipation

              Cholestasis, hepatitis, hepatic failure, hepatic function abnormality, jaundice is rare

              Tachycardia, palpitation ECG changes (eg, widened QRS)

              Arrhythmias (eg, extrasystole, heart block)

              Hypotension

              Hypertension

              Dizziness, sedation, and hypotension may occur in geriatric patients

              Dryness of mouth, nose, and throat

              Dysuria

              Urinary retention

              Impotence

              Vertigo

              Visual disturbances

              Blurred vision

              Diplopia; tinnitus

              Acute labyrinthitis

              Insomnia

              Tremors

              Nervousness

              Irritability

              Facial dyskinesia

              Tightness of the chest

              Thickening of bronchial secretions

              Wheezing

              Nasal stuffiness

              Sweating

              Chills

              Early menses

              Toxic psychosis

              Headache

              Faintness

              Paresthesia

              Agranulocytosis

              Hemolytic anemia

              Leukopenia

              Thrombocytopenia

              Pancytopenia

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              Warnings

              Contraindications

              Documented hypersensitivity

              Lower respiratory disease, eg, asthma (controversial)

              Preemies & neonates

              Nursing women

              Acute asthma, sleep apnea

              Cautions

              Caution in narrow angle glaucoma, prostatic hypertrophy, stenosing peptic ulcer, pyloroduodenal obstruction, or bladder neck obstruction

              Chlor Trimeton non-drowsy contains no chlorpheniramine, only pseudoephedrine

              All injections discontinued

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              Pregnancy & Lactation

              Pregnancy

              Antihistamine exposure in first trimester not reported to be associated with increased risk of malformations; animal studies not reported; there are no controlled data in human pregnancy; only recommended for use during pregnancy when benefit outweighs risk

              Lactation

              Excretion into human milk; the manufacturer recommends that caution be used when administering chlorpheniramine to nursing women; infants should be monitored for irritability or drowsiness; antihistamines may temporarily decrease maternal serum prolactin concentrations when administered prior to nursing infant for the first time

              Pregnancy Categories

              A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

              B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

              C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

              D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

              X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

              NA: Information not available.

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              Pharmacology

              Mechanism of Action

              Histamine H1-receptor antagonist in blood vessels, respiratory tract, and gastrointestinal tract

              Pharmacokinetics

              Half-Life elimination: 10-13 hr (children); 14-24hr (adult)

              Duration: 24 hr

              Peak Plasma Time: 2-3 hr (range 1-6 hr)

              Protein Bound: 29-37%

              Vd: 4-7 L/kg (children); 6-12 L/kg (adults)

              Metabolism: Liver (CYP2D6)

              Metabolites: Monodesmethylchlorpheniramine, didesmethylchlorpheniramine

              Excretion: Urine

              Sedative effect: Low

              Antihistamine activity: Moderate

              Anticholinergic acitivity: Moderate

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              Administration

              Parenteral forms discontinued

              IV Compatibilities

              Additive: amikacin, calcium chloride, kanamycin, norepinephrine, pentobarbital

              Syringe: diatrizoate meglumine, diatrizoate sodium, iodipamide meglumine, iothalamate meglumine, iothalamate sodium

              IV/IM Administration

              Administer SC/IM/IV injection over 1 min

              100 mg/mL injection should not be given IV

              Storage

              Store at 25C

              Protect from light

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              Images

              No images available for this drug.
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              Patient Handout

              A Patient Handout is not currently available for this monograph.
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              Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.