Dosing & Uses
Dosing Forms & Strengths
chlorpheniramine/dextromethorphan
softchew tablet
- 1mg/5mg
oral syrup
- (1mg/7.5mg)/5mL
- (2mg/15mg)/15mL
tablet
- 4mg/30mg
Cough & Cold
4mg chlorpheniramine/30mg dextromethorphan PO q6hr PRN
Dosage Forms & Strengths
chlorpheniramine/dextromethorphan
softchew tablet
- 1mg/5mg
oral syrup
- (1mg/7.5mg)/5mL
- (2mg/15mg)/15mL
tablet
- 4mg/30mg
Cough & Cold
<6 years
- Safety and efficacy not established
6-12 years
- Syrup: 2 mg chlorpheniramine/15 mg dextromethorphan PO q6hr
- Softchew tablet: 2 mg chlorpheniramine/10 mg dextromethorphan PO q4-6hr
>12 years
- 4mg chlorpheniramine/30mg dextromethorphan PO q6hr PRN
Interactions
Interaction Checker
No Results
Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor
Contraindicated (7)
- isocarboxazid
isocarboxazid and dextromethorphan both increase serotonin levels. Contraindicated.
- phenelzine
phenelzine and dextromethorphan both increase serotonin levels. Contraindicated.
- procarbazine
procarbazine and dextromethorphan both increase serotonin levels. Contraindicated. Combination is contraindicated within 2 weeks of MAOI use.
- rasagiline
rasagiline and dextromethorphan both increase serotonin levels. Contraindicated. Risk of psychosis episodes or bizarre behavior.
- safinamide
dextromethorphan, safinamide. Other (see comment). Contraindicated. Comment: Coadministration of MAOIs and dextromethorphan has been reported to cause episodes of psychosis or bizarre behavior.
- selegiline
selegiline and dextromethorphan both increase serotonin levels. Contraindicated.
- tranylcypromine
tranylcypromine and dextromethorphan both increase serotonin levels. Contraindicated.
Serious - Use Alternative (55)
- amitriptyline
amitriptyline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- amoxapine
amoxapine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- 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.
- benzhydrocodone/acetaminophen
benzhydrocodone/acetaminophen and chlorpheniramine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
- buprenorphine subdermal implant
buprenorphine subdermal implant and chlorpheniramine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
- buprenorphine transdermal
buprenorphine transdermal and chlorpheniramine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
- buprenorphine, long-acting injection
buprenorphine, long-acting injection and chlorpheniramine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
- buspirone
buspirone and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- 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.
- citalopram
citalopram and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. Combination may increase risk of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
- clomipramine
clomipramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- desipramine
desipramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- desvenlafaxine
dextromethorphan and desvenlafaxine both increase serotonin levels. Avoid or Use Alternate Drug.
- doxepin
doxepin and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- duloxetine
duloxetine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
duloxetine and dextromethorphan both increase serotonin levels. 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.
- escitalopram
escitalopram and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- fentanyl
fentanyl and chlorpheniramine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
- fentanyl intranasal
fentanyl intranasal and chlorpheniramine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
- fentanyl iontophoretic transdermal system
fentanyl iontophoretic transdermal system and chlorpheniramine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
- fentanyl transdermal
fentanyl transdermal and chlorpheniramine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
- 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.
- fluoxetine
fluoxetine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
fluoxetine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. - fluvoxamine
fluvoxamine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- grapefruit
grapefruit will increase the level or effect of dextromethorphan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
- 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 and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- 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. .
- levomilnacipran
levomilnacipran and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- linezolid
linezolid and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. Linezolid may increase serotonin as a result of MAO-A inhibition. If linezolid must be administered, discontinue serotonergic drug immediately and monitor for CNS toxicity. Serotonergic therapy may be resumed 24 hours after last linezolid dose or after 2 weeks of monitoring, whichever comes first.
- lofepramine
lofepramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- 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.
- lorcaserin
dextromethorphan and lorcaserin both increase serotonin levels. Avoid or Use Alternate Drug.
- maprotiline
maprotiline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- memantine
memantine, dextromethorphan. Either increases toxicity of the other by pharmacodynamic synergism. Contraindicated.
- meperidine
dextromethorphan and meperidine both increase serotonin levels. Avoid or Use Alternate Drug.
- methylene blue
methylene blue and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. Methylene blue may increase serotonin as a result of MAO-A inhibition. If methylene blue must be administered, discontinue serotonergic drug immediately and monitor for CNS toxicity. Serotonergic therapy may be resumed 24 hours after last methylene blue dose or after 2 weeks of monitoring, whichever comes first.
- 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 and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- nefazodone
nefazodone and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- nortriptyline
nortriptyline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- 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.
- paroxetine
paroxetine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
paroxetine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. - protriptyline
protriptyline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- selegiline transdermal
selegiline transdermal and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- sertraline
sertraline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- St John's Wort
dextromethorphan and St John's Wort both increase serotonin levels. Avoid or Use Alternate Drug.
- 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 and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- trimipramine
trimipramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
- 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 will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
venlafaxine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. - vilazodone
dextromethorphan, vilazodone. Either increases toxicity of the other by serotonin levels. Avoid or Use Alternate Drug. Concomitant therapy should be discontinued immediately if signs or symptoms of serotonin syndrome emerge and supportive symptomatic treatment should be initiated. .
- 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 (266)
- 5-HTP
5-HTP and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
- abiraterone
abiraterone increases levels of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Avoid coadministration of abiraterone with substrates of CYP2D6. If alternative therapy cannot be used, exercise caution and consider a dose reduction of the CYP2D6 substrate.
- 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.
- alfentanil
chlorpheniramine and alfentanil both increase sedation. Use Caution/Monitor.
- almotriptan
almotriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
- amisulpride
amisulpride and chlorpheniramine both increase sedation. Use Caution/Monitor.
- 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.
- amphetamine
amphetamine, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when amphemtamines are coadministered with dextromethorphan. .
- 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
dextromethorphan, aripiprazole. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
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.
- artemether/lumefantrine
artemether/lumefantrine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- asenapine
dextromethorphan, asenapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
asenapine and chlorpheniramine both increase sedation. Use Caution/Monitor. - asenapine transdermal
asenapine transdermal and chlorpheniramine both increase sedation. Use Caution/Monitor.
- bupropion
bupropion will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- avapritinib
avapritinib 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.
- brexpiprazole
brexpiprazole and chlorpheniramine both increase sedation. Use Caution/Monitor.
- brimonidine
brimonidine and chlorpheniramine both increase sedation. Use Caution/Monitor.
- brivaracetam
brivaracetam and chlorpheniramine both increase 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.
- cariprazine
dextromethorphan, cariprazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- 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).
clobazam will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Lower doses of drugs metabolized by CYP2D6 may be required when used concomitantly. - clomipramine
chlorpheniramine and clomipramine both increase sedation. Use Caution/Monitor.
- clozapine
dextromethorphan, clozapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- 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.
- cocaine topical
cocaine topical and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
- desvenlafaxine
desvenlafaxine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Desvenlafaxine inhibits CYP2D6; with higher desvenlafaxine doses (ie, 400 mg) decrease the CYP2D6 substrate dose by up to 50%; no dosage adjustment needed with desvenlafaxine doses <100 mg
- deutetrabenazine
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.
dexfenfluramine and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely. - dexmedetomidine
chlorpheniramine and dexmedetomidine both increase sedation. Use Caution/Monitor.
- dextroamphetamine
dextroamphetamine, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when amphemtamines are coadministered with dextromethorphan. .
- 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.
- dextroamphetamine transdermal
dextromethorphan, dextroamphetamine transdermal. Either increases effects of the other by serotonin levels. Modify Therapy/Monitor Closely. Initiate with lower doses and monitor for signs and symptoms of serotonin syndrome, particularly during initiation or dosage increase. If serotonin syndrome occurs, discontinue dextroamphetamine transdermal and concomitant serotonergic drug(s).
dextroamphetamine transdermal, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when amphemtamines are coadministered with dextromethorphan. . - 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.
- difelikefalin
difelikefalin and chlorpheniramine both increase sedation. Use Caution/Monitor.
- difenoxin hcl
chlorpheniramine and difenoxin hcl both increase sedation. Use Caution/Monitor.
- dihydroergotamine
dextromethorphan and dihydroergotamine both increase serotonin levels. Modify Therapy/Monitor Closely.
- dihydroergotamine intranasal
dextromethorphan and dihydroergotamine intranasal both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
- donepezil transdermal
donepezil transdermal, chlorpheniramine. Either decreases effects of the other by pharmacodynamic antagonism. 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.
- eletriptan
eletriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
- ergotamine
dextromethorphan and ergotamine both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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
fenfluramine, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Coadministration with drugs that increase serotoninergic effects may increase the risk of serotonin syndrome.
dextromethorphan and fenfluramine both increase serotonin levels. Modify Therapy/Monitor Closely.
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.
- fluphenazine
dextromethorphan, fluphenazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- 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.
- frovatriptan
frovatriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
- gepirone
gepirone and dextromethorphan both increase serotonin levels. Use Caution/Monitor. Monitor for symptoms of serotonin syndrome when gepirone is used gepirone with other drugs that may affect the serotonergic neurotransmitter systems. If serotonin syndrome occurs, consider discontinue gepirone and/or concomitant serotonergic drug.
- 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
dextromethorphan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
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.
- iloperidone
dextromethorphan, iloperidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- 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.
- isoniazid
dextromethorphan and isoniazid both increase serotonin levels. Modify Therapy/Monitor Closely.
- L-tryptophan
dextromethorphan and L-tryptophan both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
- 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 dextromethorphan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
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.
- lithium
dextromethorphan and lithium both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
dextromethorphan, loxapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction). - loxapine inhaled
dextromethorphan, loxapine inhaled. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
chlorpheniramine and loxapine inhaled both increase sedation. Use Caution/Monitor. - lsd
dextromethorphan and lsd both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
- lumefantrine
lumefantrine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- lurasidone
dextromethorphan, lurasidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- 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.
dextromethorphan and mirtazapine both increase serotonin levels. Modify Therapy/Monitor Closely. - 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.
- molindone
dextromethorphan, molindone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- 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.
dextromethorphan and morphine both increase serotonin levels. Modify Therapy/Monitor Closely. - motherwort
chlorpheniramine and motherwort both increase sedation. Use Caution/Monitor.
- naratriptan
naratriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
dextromethorphan, olanzapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction). - opium tincture
chlorpheniramine and opium tincture both increase sedation. Use Caution/Monitor.
- paliperidone
dextromethorphan, paliperidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- 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.
- panobinostat
panobinostat will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Panobinostat can increase the levels and effects of sensitive CYP2D6 substrates or those with a narrow therapeutic index CYP2D6.
- papaveretum
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.
- pazopanib
pazopanib increases levels of dextromethorphan by decreasing metabolism. Use Caution/Monitor.
- peginterferon alfa 2b
peginterferon alfa 2b, dextromethorphan. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.
- pentazocine
chlorpheniramine and pentazocine both increase sedation. Use Caution/Monitor.
dextromethorphan and pentazocine both increase serotonin levels. Modify Therapy/Monitor Closely. - pentobarbital
chlorpheniramine and pentobarbital both increase sedation. Use Caution/Monitor.
- perphenazine
dextromethorphan, perphenazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- 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.
- pimavanserin
dextromethorphan, pimavanserin. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- pimozide
dextromethorphan, pimozide. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
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.
- quetiapine
dextromethorphan, quetiapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- 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.
- quinidine
quinidine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.
- ramelteon
chlorpheniramine and ramelteon both increase sedation. Use Caution/Monitor.
- risperidone
chlorpheniramine and risperidone both increase sedation. Use Caution/Monitor.
dextromethorphan, risperidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction). - rizatriptan
rizatriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
- rolapitant
rolapitant will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor for adverse reactions when unable to avoid coadministration with narrow therapeutic index CYP2D6 substrates.
- SAMe
dextromethorphan and SAMe both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
- sumatriptan
sumatriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
- sumatriptan intranasal
sumatriptan intranasal and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
- 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.
dextromethorphan, thiothixene. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction). - topiramate
chlorpheniramine and topiramate both increase sedation. Modify Therapy/Monitor Closely.
- tramadol
dextromethorphan and tramadol both increase serotonin levels. 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.
dextromethorphan, trifluoperazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction). - trimipramine
chlorpheniramine and trimipramine both increase sedation. Use Caution/Monitor.
- ziprasidone
dextromethorphan, ziprasidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
- 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.
- zolmitriptan
zolmitriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
- zotepine
chlorpheniramine and zotepine both increase sedation. Use Caution/Monitor.
Minor (32)
- acetazolamide
acetazolamide will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- amiodarone
amiodarone will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- anastrozole
anastrozole will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- asenapine
asenapine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 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.
- celecoxib
celecoxib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- chloroquine
chloroquine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- cimetidine
cimetidine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- cyclophosphamide
cyclophosphamide will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- darifenacin
darifenacin will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- diphenhydramine
diphenhydramine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- dronedarone
dronedarone will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- eucalyptus
chlorpheniramine and eucalyptus both increase sedation. Minor/Significance Unknown.
- haloperidol
haloperidol will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- imatinib
imatinib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- larotrectinib
larotrectinib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- levoketoconazole
levoketoconazole will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- maraviroc
maraviroc will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- marijuana
marijuana will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- nettle
nettle increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. (High dose nettle; theoretical interaction) May enhance CNS depression.
- nilotinib
nilotinib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- parecoxib
parecoxib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- perphenazine
perphenazine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- propafenone
propafenone will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- quinacrine
quinacrine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- ranolazine
ranolazine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
- ribociclib
ribociclib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
- ritonavir
ritonavir will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 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.
- sertraline
sertraline will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.
Adverse Effects
Frequency Not Defined
Sedation ranging from mild drowsiness to deep sleep
CNS depression
Excitability may occur in children
Dizziness
Impaired coordination
Muscular weakness
Anorexia
Nausea
Vomiting
Urinary retention
Blurred vision
Xerostomia
Restlessness, insomnia, tremors, euphoria, nervousness, delirium, palpitations, seizures reported infrequently
Warnings
Contraindications
Hypersensitivity
Within 2 wk of taking a monoamine oxidase (MAO) inhibitor
Sedation of children
Cautions
Ask healthcare professional if trouble urinating due to enlarged prostate gland, history of glaucoma, experiencing a cough that occurs with too much phlegm (mucus), experiencing breathing problems or chronic cough that lasts or as occurs with smoking, asthma, chronic bronchitis or emphysema
If taking sedatives or tranquilizers, ask healthcare professional
Do not use more than directed
Marked drowsiness may occur; use caution when driving a motor vehicle or operating machinery
Avoid alcoholic drinks
Alcohol, sedatives, and tranquilizers may increase drowsiness
Excitability may occur, especially in children
Discontinue use and ask a healthcare professional if cough lasts more than 7 days, comes back, or is accompanied by fever, rash, or persistent headache as these could be signs of a serious condition
Pregnancy & Lactation
Pregnancy Category: C
Lactation: Unknown whether distributed in breast milk, caution advised
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Chlorpheniramine: Histamine H1-receptor antagonist; sedative effect is low; antihistamine and anticholinergic activity is moderate
Dextromethorphan: Antitussive; derivative of levorphanol; acts on cough center in medulla
Absorption
Peak Plasma Time: 2-6 hr (chlorpheniramine); 2-3 hr (dextromethorphan)
Onset: 15-30 min (dextromethorphan)
Duration: 3-6 hr (dextromethorphan)
Distribution
Protein Bound: 69-72% (chlorpheniramine)
Vd: 2.5-3.2 L/kg (chlorpheniramine)
Metabolism
Metabolism: GI mucosa, liver (chlorpheniramine); hepatic P450 enzyme CYP2D6 (dextromethorphan)
Metabolites: Monodesmethylchlorpheniramine, didesmethylchlorpheniramine
Elimination
Half-Life: 12-43 hr (chlorpheniramine); 2-4 hr (extensive dextromethorphan metabolizers); 24 hr (poor dextromethorphan metabolizers)
Excretion: Predominantly urine (chlorpheniramine and dextromethorphan)
