Indication-specific dosing for Actifed Cold and Allergy (chlorpheniramine, phenylephrine), frequency-based adverse effects, comprehensive interactions, contraindications, pregnancy & lactation schedules, and cost information.

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Sections chlorpheniramine/phenylephrine
Dosing & Uses
Interactions
Adverse Effects
Warnings
Pregnancy
Pharmacology
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Patient Handout

Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

chlorpheniramine/phenylephrine

tablet

4mg/10mg

liquid

(4mg/10mg)/5mL

liquid (drops)

(1mg/2mg)/1mL
(1mg/2.5mg)/1mL
(1-2mg/3.5-5mg)/1mL
(2mg/5mg)/1mL

Nasal Congestion or Sneezing Due to Common Cold, Hay Fever, Allergic Rhinitis

Tablet

1 tablet PO q4hr; not to exceed 6 tab/24h

Liquid

5 mL PO q4-6hr; not to exceed 30 mL/24hr

Dosage Forms & Strengths

chlorpheniramine/phenylephrine

tablet

4mg/10mg

liquid

(4mg/10mg)/5mL

liquid (drops)

(1mg/2mg)/1mL
(1mg/2.5mg)/1mL
(1-2mg/3.5-5mg)/1mL
(2mg/5mg)/1mL

Nasal Congestion or Sneezing Due to Common Cold, Hay Fever, Allergic Rhinitis

chlorpheniramine/phenylephrine

Liquid (drops)

<2 years: Not recommended
2-6 years: 1 mL [(1 mg/2.5mg)/1mL] PO q4-6hr; not to exceed 4mL/24hr; alternetively, 1 mL [(2 mg/5mg)/1mL] PO q4hr; not to exceed 3mL/24hr
6-12 years: 2 mL [(1 mg/2.5mg)/1mL] PO q4-6hr; not to exceed 4mL/24hr; alternetively, 2 mL [(2 mg/5mg)/1mL] PO q4hr; not to exceed 3mL/24hr
>12 years: 4 mL [(1 mg/2mg)/1mL] PO q4-6hr; not to exceed 4mL/24hr; alternetively, 2 mL [(2 mg/5mg)/1mL] PO q4hr; not to exceed 3mL/24hr

Liquid

>12 years: 5 mL PO q4-6hr; not to exceed 30 mL/24hr

tablet

>12 years: 1 tablet PO q4hr; not to exceed 6 tab/24h

Interaction Checker

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Contraindicated (7)

iobenguane I 123
phenylephrine decreases effects of iobenguane I 123 by receptor binding competition. Contraindicated. If clinically appropriate, discontinue drugs that compete for NE receptor sites for at least 5 half-lives; may cause false-negative imaging results.
isocarboxazid
isocarboxazid increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
linezolid
linezolid increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
phenelzine
phenelzine increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
procarbazine
procarbazine increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
selegiline transdermal
selegiline transdermal increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
tranylcypromine
tranylcypromine increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

Serious - Use Alternative (44)

amitriptyline
amitriptyline, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
amoxapine
amoxapine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
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
cabergoline
cabergoline, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
calcium/magnesium/potassium/sodium oxybates
chlorpheniramine, calcium/magnesium/potassium/sodium oxybates. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.
clomipramine
clomipramine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
desflurane
desflurane increases toxicity of phenylephrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.

desflurane increases levels of phenylephrine by decreasing metabolism. Contraindicated.
desipramine
desipramine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
dihydroergotamine
dihydroergotamine, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
dihydroergotamine intranasal
dihydroergotamine intranasal, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
doxapram
doxapram increases effects of phenylephrine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Additive pressor effect.
doxepin
doxepin, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
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.
ergoloid mesylates
ergoloid mesylates, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
ergotamine
ergotamine, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
ether
ether increases toxicity of phenylephrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.
etomidate
etomidate increases levels of phenylephrine by decreasing metabolism. Contraindicated.
fexinidazole
fexinidazole will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.
idelalisib
idelalisib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates
imipramine
imipramine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
isocarboxazid
isocarboxazid increases effects of chlorpheniramine by Other (see comment). Avoid or Use Alternate Drug. Comment: Isocarboxazid should not be administered in combination with antihistamines because of potential additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .
isoflurane
isoflurane increases toxicity of phenylephrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.
lofepramine
lofepramine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
lonafarnib
lonafarnib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with sensitive CYP3A substrates. If coadministration unavoidable, monitor for adverse reactions and reduce CYP3A substrate dose in accordance with product labeling.
maprotiline
maprotiline, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
methoxyflurane
methoxyflurane increases toxicity of phenylephrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.
methylergonovine
methylergonovine, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
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.
nortriptyline
nortriptyline, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
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.
propofol
propofol increases levels of phenylephrine by decreasing metabolism. Contraindicated.
protriptyline
protriptyline, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
sevoflurane
sevoflurane increases toxicity of phenylephrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.

sevoflurane increases levels of phenylephrine by decreasing metabolism. Contraindicated.
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, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
trimipramine
trimipramine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
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.
yohimbe
yohimbe, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

Monitor Closely (281)

acrivastine
acrivastine and chlorpheniramine both increase sedation. Use Caution/Monitor.
albuterol
albuterol and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

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

albuterol and phenylephrine both decrease sedation. Use Caution/Monitor.
alfentanil
alfentanil increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

alprazolam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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
amitriptyline increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
amisulpride
amisulpride and chlorpheniramine both increase sedation. Use Caution/Monitor.
amitriptyline
chlorpheniramine and amitriptyline both increase sedation. Use Caution/Monitor.
amobarbital
amobarbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

chlorpheniramine and amobarbital both increase sedation. Use Caution/Monitor.
amoxapine
amoxapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and amoxapine both increase sedation. Use Caution/Monitor.
apomorphine
chlorpheniramine and apomorphine both increase sedation. Use Caution/Monitor.
arformoterol
arformoterol and phenylephrine both decrease sedation. Use Caution/Monitor.

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

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.

armodafinil and phenylephrine both decrease sedation. Use Caution/Monitor.
asenapine
asenapine and chlorpheniramine both increase sedation. Use Caution/Monitor.
atomoxetine
atomoxetine, phenylephrine. Other (see comment). Use Caution/Monitor. Comment: Due to the potential for increases in blood pressure and heart rate, atomoxetine should be used cautiously with vasopressors such as phenylephrine.
asenapine transdermal
asenapine transdermal and chlorpheniramine both increase sedation. Use Caution/Monitor.
avapritinib
avapritinib and chlorpheniramine both increase sedation. Use Caution/Monitor.
azelastine
azelastine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

azelastine and chlorpheniramine both increase sedation. Use Caution/Monitor.
baclofen
chlorpheniramine and baclofen both increase sedation. Use Caution/Monitor.
belladonna and opium
belladonna and opium increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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
benperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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.

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

benzphetamine and phenylephrine both decrease sedation. Use Caution/Monitor.
brexanolone
brexanolone, chlorpheniramine. Either increases toxicity of the other by sedation. Use Caution/Monitor.
bromocriptine
bromocriptine, phenylephrine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Hypertension, V tach.
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 increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

brompheniramine and chlorpheniramine both increase sedation. Use Caution/Monitor.
buprenorphine
chlorpheniramine and buprenorphine both increase sedation. Use Caution/Monitor.
buprenorphine buccal
buprenorphine buccal increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
buprenorphine buccal
chlorpheniramine and buprenorphine buccal both increase sedation. Use Caution/Monitor.
butabarbital
butabarbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

butalbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
butorphanol
chlorpheniramine and butorphanol both increase sedation. Use Caution/Monitor.

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

caffeine and phenylephrine both decrease sedation. Use Caution/Monitor.
carbinoxamine
carbinoxamine and chlorpheniramine both increase sedation. Use Caution/Monitor.

carbinoxamine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
carisoprodol
chlorpheniramine and carisoprodol both increase sedation. Use Caution/Monitor.
chloral hydrate
chloral hydrate increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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.

chlordiazepoxide increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
chlorpheniramine
chlorpheniramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
chlorpromazine
chlorpheniramine and chlorpromazine both increase sedation. Use Caution/Monitor.
chlorpromazine
chlorpromazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpromazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
chlorzoxazone
chlorpheniramine and chlorzoxazone both increase sedation. Use Caution/Monitor.
cinnarizine
chlorpheniramine and cinnarizine both increase sedation. Use Caution/Monitor.

cinnarizine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
clemastine
chlorpheniramine and clemastine both increase sedation. Use Caution/Monitor.

clemastine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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
clomipramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
clomipramine
chlorpheniramine and clomipramine both increase sedation. Use Caution/Monitor.
clonazepam
clonazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

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

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

codeine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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
cyclizine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
cyclizine
chlorpheniramine and cyclizine both increase sedation. Use Caution/Monitor.
cyclobenzaprine
chlorpheniramine and cyclobenzaprine both increase sedation. Use Caution/Monitor.
cyproheptadine
cyproheptadine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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.
desipramine
desipramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
dantrolene
chlorpheniramine and dantrolene both increase sedation. Use Caution/Monitor.
daridorexant
chlorpheniramine and daridorexant both increase sedation. Modify Therapy/Monitor Closely. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.
desflurane
desflurane and chlorpheniramine both increase sedation. Use Caution/Monitor.
desipramine
chlorpheniramine and desipramine both increase sedation. Use Caution/Monitor.
deutetrabenazine
chlorpheniramine and deutetrabenazine both increase sedation. Use Caution/Monitor.
dexchlorpheniramine
dexchlorpheniramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

dexfenfluramine and phenylephrine both decrease sedation. Use Caution/Monitor.
dexmedetomidine
dexmedetomidine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and dexmedetomidine both increase sedation. Use Caution/Monitor.
dexmethylphenidate
dexmethylphenidate and phenylephrine both decrease sedation. Use Caution/Monitor.

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

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

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

dextroamphetamine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
dextromoramide
chlorpheniramine and dextromoramide both increase sedation. Use Caution/Monitor.

dextromoramide increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
diamorphine
chlorpheniramine and diamorphine both increase sedation. Use Caution/Monitor.

diamorphine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
diazepam
chlorpheniramine and diazepam both increase sedation. Use Caution/Monitor.
diethylpropion
diethylpropion and phenylephrine both decrease sedation. Use Caution/Monitor.

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

chlorpheniramine and difenoxin hcl both increase sedation. Use Caution/Monitor.
dimenhydrinate
dimenhydrinate increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and dimenhydrinate both increase sedation. Use Caution/Monitor.
diphenhydramine
diphenhydramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

diphenoxylate hcl increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
dipipanone
chlorpheniramine and dipipanone both increase sedation. Use Caution/Monitor.

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

dobutamine and phenylephrine both decrease sedation. Use Caution/Monitor.

dobutamine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
donepezil transdermal
donepezil transdermal, chlorpheniramine. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.
dopamine
dopamine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

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

dopexamine and phenylephrine both decrease sedation. Use Caution/Monitor.
dosulepin
chlorpheniramine and dosulepin both increase sedation. Use Caution/Monitor.
doxepin
doxepin increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
doxepin
chlorpheniramine and doxepin both increase sedation. Use Caution/Monitor.
doxylamine
chlorpheniramine and doxylamine both increase sedation. Use Caution/Monitor.
droperidol
droperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and droperidol both increase sedation. Use Caution/Monitor.
droxidopa
phenylephrine and droxidopa both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. May increase risk for supine hypertension
efavirenz
efavirenz will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
elagolix
elagolix will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.
elvitegravir/cobicistat/emtricitabine/tenofovir DF
elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.
ephedrine
ephedrine, phenylephrine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.

ephedrine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

ephedrine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
epinephrine
epinephrine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

chlorpheniramine increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
epinephrine inhaled
phenylephrine, epinephrine inhaled. Either increases effects of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
epinephrine racemic
chlorpheniramine increases and epinephrine racemic decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
epinephrine racemic
epinephrine racemic and phenylephrine both decrease sedation. Use Caution/Monitor.

epinephrine racemic and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
esketamine intranasal
esketamine intranasal, chlorpheniramine. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely.
estazolam
estazolam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and estazolam both increase sedation. Use Caution/Monitor.
ethanol
ethanol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and ethanol both increase sedation. Use Caution/Monitor.
etomidate
etomidate and chlorpheniramine both increase sedation. Use Caution/Monitor.
fenfluramine
fenfluramine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

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

fluphenazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
flurazepam
chlorpheniramine and flurazepam both increase sedation. Use Caution/Monitor.

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

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

formoterol and phenylephrine both decrease sedation. Use Caution/Monitor.
fosphenytoin
fosphenytoin will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
haloperidol
haloperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
gabapentin
gabapentin, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.
gabapentin enacarbil
gabapentin enacarbil, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.
ganaxolone
chlorpheniramine and ganaxolone both increase sedation. Use Caution/Monitor.
glycopyrronium tosylate topical
glycopyrronium tosylate topical, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration of glycopyrronium tosylate topical with other anticholinergic medications may result in additive anticholinergic adverse effects.
gotu kola
gotu kola increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.
haloperidol
chlorpheniramine and haloperidol both increase sedation. Use Caution/Monitor.
hawthorn
hawthorn increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.
hops
hops increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.
hyaluronidase
chlorpheniramine decreases effects of hyaluronidase by Other (see comment). Use Caution/Monitor. Comment: Antihistamines, when given in large systemic doses, may render tissues partially resistant to the action of hyaluronidase. Patients may require larger amounts of hyaluronidase for equivalent dispersing effect.
hydralazine
hydralazine, phenylephrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.
hydromorphone
chlorpheniramine and hydromorphone both increase sedation. Use Caution/Monitor.

hydromorphone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
hydroxyzine
chlorpheniramine and hydroxyzine both increase sedation. Use Caution/Monitor.

hydroxyzine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
iloperidone
chlorpheniramine and iloperidone both increase sedation. Use Caution/Monitor.

iloperidone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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.

imipramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
indacaterol, inhaled
phenylephrine increases effects of indacaterol, inhaled by Other (see comment). Use Caution/Monitor. Comment: If additional adrenergic drugs are to be administered by any route, they should be used with caution because the sympathetic effects of indacaterol may be potentiated.
isoproterenol
chlorpheniramine increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
insulin degludec
phenylephrine decreases effects of insulin degludec by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.
insulin degludec/insulin aspart
phenylephrine decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.
insulin inhaled
phenylephrine decreases effects of insulin inhaled by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.
isoproterenol
isoproterenol and phenylephrine both decrease sedation. Use Caution/Monitor.

isoproterenol and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
istradefylline
istradefylline will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.
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.

ketotifen, ophthalmic increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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.
levalbuterol
levalbuterol and phenylephrine both decrease sedation. Use Caution/Monitor.

levalbuterol and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
lemborexant
lemborexant, chlorpheniramine. Either increases effects of the other by sedation. Modify Therapy/Monitor Closely. Dosage adjustment may be necessary if lemborexant is coadministered with other CNS depressants because of potentially additive effects.
lenacapavir
lenacapavir will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir (a moderate CYP3A4 inhibitor) may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.
letermovir
letermovir increases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
levalbuterol
chlorpheniramine increases and levalbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
levorphanol
levorphanol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and levorphanol both increase sedation. Use Caution/Monitor.
lisdexamfetamine
lisdexamfetamine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

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

lisdexamfetamine and phenylephrine both decrease sedation. Use Caution/Monitor.
lofepramine
chlorpheniramine and lofepramine both increase sedation. Use Caution/Monitor.

lofepramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
lofexidine
chlorpheniramine and lofexidine both increase sedation. Use Caution/Monitor.

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

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

lorazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
lormetazepam
chlorpheniramine and lormetazepam both increase sedation. Use Caution/Monitor.

lormetazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
loxapine
chlorpheniramine and loxapine both increase sedation. Use Caution/Monitor.

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

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
maprotiline increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
maprotiline
chlorpheniramine and maprotiline both increase sedation. Use Caution/Monitor.
marijuana
chlorpheniramine and marijuana both increase sedation. Use Caution/Monitor.

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

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

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

chlorpheniramine and meprobamate both increase sedation. Use Caution/Monitor.
metaproterenol
metaproterenol and phenylephrine both decrease sedation. Use Caution/Monitor.

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

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

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

methamphetamine and phenylephrine both decrease sedation. Use Caution/Monitor.
methocarbamol
chlorpheniramine and methocarbamol both increase sedation. Use Caution/Monitor.
methyldopa
methyldopa increases effects of phenylephrine by unknown mechanism. Use Caution/Monitor.
methylenedioxymethamphetamine
chlorpheniramine increases and methylenedioxymethamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

methylenedioxymethamphetamine and phenylephrine both decrease sedation. Use Caution/Monitor.
midazolam
midazolam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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
midodrine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

mirtazapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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
modafinil and phenylephrine both decrease sedation. Use Caution/Monitor.
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.

morphine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
motherwort
chlorpheniramine and motherwort both increase sedation. Use Caution/Monitor.

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

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

nabilone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
nadolol
nadolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).
nalbuphine
chlorpheniramine and nalbuphine both increase sedation. Use Caution/Monitor.
nalbuphine
nalbuphine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
norepinephrine
norepinephrine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

chlorpheniramine increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
nortriptyline
chlorpheniramine and nortriptyline both increase sedation. Use Caution/Monitor.

nortriptyline increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
olanzapine
chlorpheniramine and olanzapine both increase sedation. Use Caution/Monitor.

olanzapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
olodaterol inhaled
phenylephrine and olodaterol inhaled both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Caution with coadministration of adrenergic drugs by any route because of additive sympathetic effects
opium tincture
chlorpheniramine and opium tincture both increase sedation. Use Caution/Monitor.
opium tincture
opium tincture increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
orphenadrine
chlorpheniramine and orphenadrine both increase sedation. Use Caution/Monitor.
oxazepam
oxazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and oxazepam both increase sedation. Use Caution/Monitor.
oxycodone
oxycodone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and oxycodone both increase sedation. Use Caution/Monitor.
oxymetazoline topical
oxymetazoline topical and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
oxymorphone
chlorpheniramine and oxymorphone both increase sedation. Use Caution/Monitor.
oxymorphone
oxymorphone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
oxytocin
oxytocin increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor.
paliperidone
chlorpheniramine and paliperidone both increase sedation. Use Caution/Monitor.

paliperidone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
papaveretum
chlorpheniramine and papaveretum both increase sedation. Use Caution/Monitor.

papaveretum increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
papaverine
chlorpheniramine and papaverine both increase sedation. Use Caution/Monitor.
pentazocine
pentazocine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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
pentobarbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and pentobarbital both increase sedation. Use Caution/Monitor.
perphenazine
perphenazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

perphenazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.

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.

phendimetrazine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

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

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

chlorpheniramine and pimozide both increase sedation. Use Caution/Monitor.
pindolol
pindolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).
pirbuterol
chlorpheniramine increases and pirbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
pirbuterol
pirbuterol and phenylephrine both decrease sedation. Use Caution/Monitor.

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

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

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

prochlorperazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
promazine
promazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
promethazine
chlorpheniramine and promethazine both increase sedation. Use Caution/Monitor.
promethazine
promethazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

promethazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
propofol
propofol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

propofol and chlorpheniramine both increase sedation. Use Caution/Monitor.
propranolol
propranolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).
propylhexedrine
chlorpheniramine increases and propylhexedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
propylhexedrine
phenylephrine and propylhexedrine both decrease sedation. Use Caution/Monitor.

phenylephrine and propylhexedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
protriptyline
chlorpheniramine and protriptyline both increase sedation. Use Caution/Monitor.

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

chlorpheniramine and quetiapine both increase sedation. Use Caution/Monitor.
ramelteon
chlorpheniramine and ramelteon both increase sedation. Use Caution/Monitor.
rasagiline
rasagiline increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode.
risperidone
risperidone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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.
safinamide
phenylephrine and safinamide both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Monitor patients for hypertension if safinamide is prescribed concomitantly with prescription or nonprescription sympathomimetics, including nasal, oral, or ophthalmic decongestants and cold remedies.
salmeterol
chlorpheniramine increases and salmeterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

salmeterol and phenylephrine both decrease sedation. Use Caution/Monitor.
scullcap
chlorpheniramine and scullcap both increase sedation. Use Caution/Monitor.

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

chlorpheniramine and secobarbital both increase sedation. Use Caution/Monitor.
selegiline
selegiline increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode.
sevoflurane
sevoflurane and chlorpheniramine both increase sedation. Use Caution/Monitor.
serdexmethylphenidate/dexmethylphenidate
serdexmethylphenidate/dexmethylphenidate and phenylephrine both decrease sedation. Use Caution/Monitor.

serdexmethylphenidate/dexmethylphenidate and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
shepherd's purse
chlorpheniramine and shepherd's purse both increase sedation. Use Caution/Monitor.

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

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

tapentadol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
tazemetostat
tazemetostat will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
temazepam
temazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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
terbutaline and phenylephrine both decrease sedation. Use Caution/Monitor.

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

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.

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

thioridazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
thiothixene
chlorpheniramine and thiothixene both increase sedation. Use Caution/Monitor.

thiothixene increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
timolol
timolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).
topiramate
chlorpheniramine and topiramate both increase sedation. Modify Therapy/Monitor Closely.
topiramate
topiramate increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.
tramadol
chlorpheniramine and tramadol both increase sedation. Use Caution/Monitor.

tramadol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
trazodone
chlorpheniramine and trazodone both increase sedation. Use Caution/Monitor.

trazodone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
triazolam
chlorpheniramine and triazolam both increase sedation. Use Caution/Monitor.

triazolam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
triclofos
chlorpheniramine and triclofos both increase sedation. Use Caution/Monitor.

triclofos increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
trifluoperazine
chlorpheniramine and trifluoperazine both increase sedation. Use Caution/Monitor.

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

trifluoperazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
trimipramine
trimipramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and trimipramine both increase sedation. Use Caution/Monitor.
triprolidine
triprolidine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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
phenylephrine and xylometazoline both decrease sedation. Use Caution/Monitor.

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

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

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.

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

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

Minor (22)

acetazolamide
acetazolamide will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
alfuzosin
alfuzosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. 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, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
ashwagandha
ashwagandha increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. May enhance CNS depression.
brimonidine
brimonidine increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. Increased CNS depression.
cyclophosphamide
cyclophosphamide will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
desmopressin
desmopressin increases effects of phenylephrine by pharmacodynamic synergism. Minor/Significance Unknown.
doxazosin
doxazosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
eucalyptus
eucalyptus increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.

chlorpheniramine and eucalyptus both increase sedation. Minor/Significance Unknown.
larotrectinib
larotrectinib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
moxisylyte
moxisylyte, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
levoketoconazole
levoketoconazole will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 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.
phenoxybenzamine
phenoxybenzamine, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
phentolamine
phentolamine, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
prazosin
prazosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
ribociclib
ribociclib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
sage
sage increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.

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.
silodosin
silodosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
terazosin
terazosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.

acetazolamide
Minor (1)acetazolamide will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
acrivastine
Monitor Closely (1)acrivastine and chlorpheniramine both increase sedation. Use Caution/Monitor.
albuterol
Monitor Closely (3)chlorpheniramine increases and albuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

albuterol and phenylephrine both decrease sedation. Use Caution/Monitor.
alfentanil
Monitor Closely (2)alfentanil increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and alfentanil both increase sedation. Use Caution/Monitor.
alfuzosin
Minor (1)alfuzosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
alprazolam
Monitor Closely (2)chlorpheniramine and alprazolam both increase sedation. Use Caution/Monitor.

alprazolam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
amifampridine
Monitor Closely (1)chlorpheniramine increases toxicity of amifampridine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Amifampridine can cause seizures. Coadministration with drugs that lower seizure threshold may increase this risk.
amisulpride
Monitor Closely (1)amisulpride and chlorpheniramine both increase sedation. Use Caution/Monitor.
amitriptyline
Monitor Closely (2)amitriptyline increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and amitriptyline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)amitriptyline, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
amobarbital
Monitor Closely (3)amobarbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

chlorpheniramine and amobarbital both increase sedation. Use Caution/Monitor.
amoxapine
Monitor Closely (2)amoxapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and amoxapine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)amoxapine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
anastrozole
Minor (1)anastrozole will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
apalutamide
Serious - Use Alternative (1)apalutamide will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.
apomorphine
Monitor Closely (1)chlorpheniramine and apomorphine both increase sedation. Use Caution/Monitor.
arformoterol
Monitor Closely (3)chlorpheniramine increases and arformoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

arformoterol and phenylephrine both decrease sedation. Use Caution/Monitor.
aripiprazole
Monitor Closely (2)aripiprazole increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and aripiprazole both increase sedation. Use Caution/Monitor.
armodafinil
Monitor Closely (2)chlorpheniramine increases and armodafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

armodafinil and phenylephrine both decrease sedation. Use Caution/Monitor.
asenapine
Monitor Closely (1)asenapine and chlorpheniramine both increase sedation. Use Caution/Monitor.Minor (1)asenapine, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
asenapine transdermal
Monitor Closely (1)asenapine transdermal and chlorpheniramine both increase sedation. Use Caution/Monitor.
ashwagandha
Minor (1)ashwagandha increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. May enhance CNS depression.
atomoxetine
Monitor Closely (1)atomoxetine, phenylephrine. Other (see comment). Use Caution/Monitor. Comment: Due to the potential for increases in blood pressure and heart rate, atomoxetine should be used cautiously with vasopressors such as phenylephrine.
avapritinib
Monitor Closely (1)avapritinib and chlorpheniramine both increase sedation. Use Caution/Monitor.
azelastine
Monitor Closely (2)azelastine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

azelastine and chlorpheniramine both increase sedation. Use Caution/Monitor.
baclofen
Monitor Closely (1)chlorpheniramine and baclofen both increase sedation. Use Caution/Monitor.
belladonna and opium
Monitor Closely (2)chlorpheniramine and belladonna and opium both increase sedation. Use Caution/Monitor.

belladonna and opium increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
belzutifan
Monitor Closely (1)belzutifan will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If unable to avoid coadministration of belzutifan with sensitive CYP3A4 substrates, consider increasing the sensitive CYP3A4 substrate dose in accordance with its prescribing information.
benperidol
Monitor Closely (2)chlorpheniramine and benperidol both increase sedation. Use Caution/Monitor.

benperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
benzhydrocodone/acetaminophen
Serious - Use Alternative (1)benzhydrocodone/acetaminophen and chlorpheniramine both increase sedation. Avoid or Use Alternate Drug. Limit use to patients for whom alternative treatment options are inadequate
benzphetamine
Monitor Closely (3)chlorpheniramine increases and benzphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

benzphetamine and phenylephrine both decrease sedation. Use Caution/Monitor.
brexanolone
Monitor Closely (1)brexanolone, chlorpheniramine. Either increases toxicity of the other by sedation. Use Caution/Monitor.
brexpiprazole
Monitor Closely (1)brexpiprazole and chlorpheniramine both increase sedation. Use Caution/Monitor.
brimonidine
Monitor Closely (1)brimonidine and chlorpheniramine both increase sedation. Use Caution/Monitor.Minor (1)brimonidine increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. Increased CNS depression.
brivaracetam
Monitor Closely (1)brivaracetam and chlorpheniramine both increase sedation. Use Caution/Monitor.
bromocriptine
Monitor Closely (1)bromocriptine, phenylephrine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Hypertension, V tach.
brompheniramine
Monitor Closely (2)brompheniramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

brompheniramine and chlorpheniramine both increase sedation. Use Caution/Monitor.
buprenorphine
Monitor Closely (1)chlorpheniramine and buprenorphine both increase sedation. Use Caution/Monitor.
buprenorphine buccal
Monitor Closely (2)chlorpheniramine and buprenorphine buccal both increase sedation. Use Caution/Monitor.

buprenorphine buccal increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
buprenorphine subdermal implant
Serious - Use Alternative (1)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
Serious - Use Alternative (1)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
Serious - Use Alternative (1)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
butabarbital
Monitor Closely (2)chlorpheniramine and butabarbital both increase sedation. Use Caution/Monitor.

butabarbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
butalbital
Monitor Closely (2)chlorpheniramine and butalbital both increase sedation. Use Caution/Monitor.

butalbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
butorphanol
Monitor Closely (2)chlorpheniramine and butorphanol both increase sedation. Use Caution/Monitor.

butorphanol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
cabergoline
Serious - Use Alternative (1)cabergoline, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
caffeine
Monitor Closely (2)chlorpheniramine increases and caffeine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

caffeine and phenylephrine both decrease sedation. Use Caution/Monitor.
calcium/magnesium/potassium/sodium oxybates
Serious - Use Alternative (1)chlorpheniramine, calcium/magnesium/potassium/sodium oxybates. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.
carbinoxamine
Monitor Closely (2)carbinoxamine and chlorpheniramine both increase sedation. Use Caution/Monitor.

carbinoxamine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
carisoprodol
Monitor Closely (1)chlorpheniramine and carisoprodol both increase sedation. Use Caution/Monitor.
cenobamate
Monitor Closely (2)cenobamate, chlorpheniramine. Either increases effects of the other by sedation. Use Caution/Monitor.

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

chloral hydrate increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
chlordiazepoxide
Monitor Closely (2)chlorpheniramine and chlordiazepoxide both increase sedation. Use Caution/Monitor.

chlordiazepoxide increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
chlorpheniramine
Monitor Closely (1)chlorpheniramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
chlorpromazine
Monitor Closely (3)chlorpheniramine and chlorpromazine both increase sedation. Use Caution/Monitor.

chlorpromazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.

chlorpromazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
chlorzoxazone
Monitor Closely (1)chlorpheniramine and chlorzoxazone both increase sedation. Use Caution/Monitor.
cinnarizine
Monitor Closely (2)chlorpheniramine and cinnarizine both increase sedation. Use Caution/Monitor.

cinnarizine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
clemastine
Monitor Closely (2)chlorpheniramine and clemastine both increase sedation. Use Caution/Monitor.

clemastine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
clobazam
Monitor Closely (1)chlorpheniramine, clobazam. Other (see comment). Use Caution/Monitor. Comment: Concomitant administration can increase the potential for CNS effects (e.g., increased sedation or respiratory depression).
clomipramine
Monitor Closely (2)chlorpheniramine and clomipramine both increase sedation. Use Caution/Monitor.

clomipramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)clomipramine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
clonazepam
Monitor Closely (2)chlorpheniramine and clonazepam both increase sedation. Use Caution/Monitor.

clonazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
clorazepate
Monitor Closely (2)chlorpheniramine and clorazepate both increase sedation. Use Caution/Monitor.

clorazepate increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
clozapine
Monitor Closely (2)clozapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

codeine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
crofelemer
Monitor Closely (1)crofelemer increases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.
cyclizine
Monitor Closely (2)cyclizine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and cyclizine both increase sedation. Use Caution/Monitor.
cyclobenzaprine
Monitor Closely (1)chlorpheniramine and cyclobenzaprine both increase sedation. Use Caution/Monitor.
cyclophosphamide
Minor (1)cyclophosphamide will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
cyproheptadine
Monitor Closely (2)chlorpheniramine and cyproheptadine both increase sedation. Use Caution/Monitor.

cyproheptadine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
dabrafenib
Monitor Closely (1)dabrafenib will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.
dantrolene
Monitor Closely (1)chlorpheniramine and dantrolene both increase sedation. Use Caution/Monitor.
daridorexant
Monitor Closely (1)chlorpheniramine and daridorexant both increase sedation. Modify Therapy/Monitor Closely. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.
desflurane
Monitor Closely (1)desflurane and chlorpheniramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)desflurane increases toxicity of phenylephrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.

desflurane increases levels of phenylephrine by decreasing metabolism. Contraindicated.
desipramine
Monitor Closely (2)chlorpheniramine and desipramine both increase sedation. Use Caution/Monitor.

desipramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)desipramine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
desmopressin
Minor (1)desmopressin increases effects of phenylephrine by pharmacodynamic synergism. Minor/Significance Unknown.
deutetrabenazine
Monitor Closely (1)chlorpheniramine and deutetrabenazine both increase sedation. Use Caution/Monitor.
dexchlorpheniramine
Monitor Closely (2)dexchlorpheniramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and dexchlorpheniramine both increase sedation. Use Caution/Monitor.
dexfenfluramine
Monitor Closely (3)chlorpheniramine increases and dexfenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

dexfenfluramine and phenylephrine both decrease sedation. Use Caution/Monitor.
dexmedetomidine
Monitor Closely (2)dexmedetomidine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and dexmedetomidine both increase sedation. Use Caution/Monitor.
dexmethylphenidate
Monitor Closely (3)dexmethylphenidate and phenylephrine both decrease sedation. Use Caution/Monitor.

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

dexmethylphenidate and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
dextroamphetamine
Monitor Closely (3)dextroamphetamine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

dextroamphetamine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
dextromoramide
Monitor Closely (2)chlorpheniramine and dextromoramide both increase sedation. Use Caution/Monitor.

dextromoramide increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
diamorphine
Monitor Closely (2)chlorpheniramine and diamorphine both increase sedation. Use Caution/Monitor.

diamorphine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
diazepam
Monitor Closely (1)chlorpheniramine and diazepam both increase sedation. Use Caution/Monitor.
diazepam intranasal
Monitor Closely (1)diazepam intranasal, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration may potentiate the CNS-depressant effects of each drug.
diethylpropion
Monitor Closely (3)diethylpropion and phenylephrine both decrease sedation. Use Caution/Monitor.

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

chlorpheniramine increases and diethylpropion decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
difelikefalin
Monitor Closely (1)difelikefalin and chlorpheniramine both increase sedation. Use Caution/Monitor.
difenoxin hcl
Monitor Closely (2)difenoxin hcl increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and difenoxin hcl both increase sedation. Use Caution/Monitor.
dihydroergotamine
Serious - Use Alternative (1)dihydroergotamine, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
dihydroergotamine intranasal
Serious - Use Alternative (1)dihydroergotamine intranasal, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
dimenhydrinate
Monitor Closely (2)dimenhydrinate increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and dimenhydrinate both increase sedation. Use Caution/Monitor.
diphenhydramine
Monitor Closely (2)diphenhydramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and diphenhydramine both increase sedation. Use Caution/Monitor.
diphenoxylate hcl
Monitor Closely (2)chlorpheniramine and diphenoxylate hcl both increase sedation. Use Caution/Monitor.

diphenoxylate hcl increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
dipipanone
Monitor Closely (2)chlorpheniramine and dipipanone both increase sedation. Use Caution/Monitor.

dipipanone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
dobutamine
Monitor Closely (3)chlorpheniramine increases and dobutamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

dobutamine and phenylephrine both decrease sedation. Use Caution/Monitor.

dobutamine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
donepezil transdermal
Monitor Closely (1)donepezil transdermal, chlorpheniramine. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.
dopamine
Monitor Closely (3)chlorpheniramine increases and dopamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

dopamine and phenylephrine both decrease sedation. Use Caution/Monitor.

dopamine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
dopexamine
Monitor Closely (3)chlorpheniramine increases and dopexamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

dopexamine and phenylephrine both decrease sedation. Use Caution/Monitor.
dosulepin
Monitor Closely (1)chlorpheniramine and dosulepin both increase sedation. Use Caution/Monitor.
doxapram
Serious - Use Alternative (1)doxapram increases effects of phenylephrine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Additive pressor effect.
doxazosin
Minor (1)doxazosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
doxepin
Monitor Closely (2)doxepin increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and doxepin both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)doxepin, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
doxylamine
Monitor Closely (1)chlorpheniramine and doxylamine both increase sedation. Use Caution/Monitor.
droperidol
Monitor Closely (2)chlorpheniramine and droperidol both increase sedation. Use Caution/Monitor.

droperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
droxidopa
Monitor Closely (1)phenylephrine and droxidopa both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. May increase risk for supine hypertension
efavirenz
Monitor Closely (1)efavirenz will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
elagolix
Monitor Closely (1)elagolix will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.
eluxadoline
Serious - Use Alternative (1)chlorpheniramine, eluxadoline. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration with other drugs that cause constipation. Increases risk for constipation related serious adverse reactions.
elvitegravir/cobicistat/emtricitabine/tenofovir DF
Monitor Closely (1)elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.
ephedrine
Monitor Closely (4)ephedrine, phenylephrine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.

ephedrine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

ephedrine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
epinephrine
Monitor Closely (3)epinephrine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

chlorpheniramine increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
epinephrine inhaled
Monitor Closely (1)phenylephrine, epinephrine inhaled. Either increases effects of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
epinephrine racemic
Monitor Closely (3)chlorpheniramine increases and epinephrine racemic decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

epinephrine racemic and phenylephrine both decrease sedation. Use Caution/Monitor.
ergoloid mesylates
Serious - Use Alternative (1)ergoloid mesylates, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
ergotamine
Serious - Use Alternative (1)ergotamine, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
esketamine intranasal
Monitor Closely (1)esketamine intranasal, chlorpheniramine. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely.
estazolam
Monitor Closely (2)estazolam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and estazolam both increase sedation. Use Caution/Monitor.
ethanol
Monitor Closely (2)ethanol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and ethanol both increase sedation. Use Caution/Monitor.
ether
Serious - Use Alternative (1)ether increases toxicity of phenylephrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.
etomidate
Monitor Closely (1)etomidate and chlorpheniramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)etomidate increases levels of phenylephrine by decreasing metabolism. Contraindicated.
eucalyptus
Minor (2)eucalyptus increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.

chlorpheniramine and eucalyptus both increase sedation. Minor/Significance Unknown.
fedratinib
Monitor Closely (1)fedratinib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.
fenfluramine
Monitor Closely (3)fenfluramine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

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

fenfluramine and phenylephrine both decrease sedation. Use Caution/Monitor.
fentanyl
Monitor Closely (1)fentanyl, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.
fentanyl intranasal
Monitor Closely (1)fentanyl intranasal, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.
fentanyl transdermal
Monitor Closely (1)fentanyl transdermal, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.
fentanyl transmucosal
Monitor Closely (1)fentanyl transmucosal, chlorpheniramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with anticholinergics may increase risk for urinary retention and/or severe constipation, which may lead to paralytic ileus.
fexinidazole
Serious - Use Alternative (1)fexinidazole will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.
flibanserin
Monitor Closely (1)chlorpheniramine and flibanserin both increase sedation. Modify Therapy/Monitor Closely. Risk for sedation increased if flibanserin is coadministration with other CNS depressants.
fluphenazine
Monitor Closely (3)fluphenazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

fluphenazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
flurazepam
Monitor Closely (2)chlorpheniramine and flurazepam both increase sedation. Use Caution/Monitor.

flurazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
formoterol
Monitor Closely (3)chlorpheniramine increases and formoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

formoterol and phenylephrine both decrease sedation. Use Caution/Monitor.
fosphenytoin
Monitor Closely (1)fosphenytoin will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
gabapentin
Monitor Closely (1)gabapentin, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.
gabapentin enacarbil
Monitor Closely (1)gabapentin enacarbil, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.
ganaxolone
Monitor Closely (1)chlorpheniramine and ganaxolone both increase sedation. Use Caution/Monitor.
glycopyrronium tosylate topical
Monitor Closely (1)glycopyrronium tosylate topical, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration of glycopyrronium tosylate topical with other anticholinergic medications may result in additive anticholinergic adverse effects.
gotu kola
Monitor Closely (1)gotu kola increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.
haloperidol
Monitor Closely (2)haloperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and haloperidol both increase sedation. Use Caution/Monitor.
hawthorn
Monitor Closely (1)hawthorn increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.
hops
Monitor Closely (1)hops increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.
hyaluronidase
Monitor Closely (1)chlorpheniramine decreases effects of hyaluronidase by Other (see comment). Use Caution/Monitor. Comment: Antihistamines, when given in large systemic doses, may render tissues partially resistant to the action of hyaluronidase. Patients may require larger amounts of hyaluronidase for equivalent dispersing effect.
hydralazine
Monitor Closely (1)hydralazine, phenylephrine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.
hydromorphone
Monitor Closely (2)chlorpheniramine and hydromorphone both increase sedation. Use Caution/Monitor.

hydromorphone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
hydroxyzine
Monitor Closely (2)chlorpheniramine and hydroxyzine both increase sedation. Use Caution/Monitor.

hydroxyzine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
idelalisib
Serious - Use Alternative (1)idelalisib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates
iloperidone
Monitor Closely (3)chlorpheniramine and iloperidone both increase sedation. Use Caution/Monitor.

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

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

imipramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)imipramine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
indacaterol, inhaled
Monitor Closely (1)phenylephrine increases effects of indacaterol, inhaled by Other (see comment). Use Caution/Monitor. Comment: If additional adrenergic drugs are to be administered by any route, they should be used with caution because the sympathetic effects of indacaterol may be potentiated.
insulin degludec
Monitor Closely (1)phenylephrine decreases effects of insulin degludec by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.
insulin degludec/insulin aspart
Monitor Closely (1)phenylephrine decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.
insulin inhaled
Monitor Closely (1)phenylephrine decreases effects of insulin inhaled by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Sympathomimetics increase blood glucose by stimulating alpha and beta receptors; this action results in increased hepatic glucose production, glycogenolysis, and decreased insulin secretion.
iobenguane I 123
Contraindicated (1)phenylephrine decreases effects of iobenguane I 123 by receptor binding competition. Contraindicated. If clinically appropriate, discontinue drugs that compete for NE receptor sites for at least 5 half-lives; may cause false-negative imaging results.
isocarboxazid
Contraindicated (1)isocarboxazid increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.Serious - Use Alternative (1)isocarboxazid increases effects of chlorpheniramine by Other (see comment). Avoid or Use Alternate Drug. Comment: Isocarboxazid should not be administered in combination with antihistamines because of potential additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .
isoflurane
Serious - Use Alternative (1)isoflurane increases toxicity of phenylephrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.
isoproterenol
Monitor Closely (3)chlorpheniramine increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

isoproterenol and phenylephrine both decrease sedation. Use Caution/Monitor.

isoproterenol and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
istradefylline
Monitor Closely (1)istradefylline will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.
kava
Monitor Closely (1)kava increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.
ketamine
Monitor Closely (1)ketamine and chlorpheniramine both increase sedation. Use Caution/Monitor.
ketotifen, ophthalmic
Monitor Closely (2)chlorpheniramine and ketotifen, ophthalmic both increase sedation. Use Caution/Monitor.

ketotifen, ophthalmic increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
larotrectinib
Minor (1)larotrectinib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
lasmiditan
Monitor Closely (1)lasmiditan, chlorpheniramine. Either increases effects of the other by sedation. Use Caution/Monitor. Coadministration of lasmiditan and other CNS depressant drugs, including alcohol have not been evaluated in clinical studies. Lasmiditan may cause sedation, as well as other cognitive and/or neuropsychiatric adverse reactions.
lemborexant
Monitor Closely (1)lemborexant, chlorpheniramine. Either increases effects of the other by sedation. Modify Therapy/Monitor Closely. Dosage adjustment may be necessary if lemborexant is coadministered with other CNS depressants because of potentially additive effects.
lenacapavir
Monitor Closely (1)lenacapavir will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir (a moderate CYP3A4 inhibitor) may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.
letermovir
Monitor Closely (1)letermovir increases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
levalbuterol
Monitor Closely (3)chlorpheniramine increases and levalbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

levalbuterol and phenylephrine both decrease sedation. Use Caution/Monitor.
levoketoconazole
Minor (1)levoketoconazole will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
levorphanol
Monitor Closely (2)levorphanol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and levorphanol both increase sedation. Use Caution/Monitor.
linezolid
Contraindicated (1)linezolid increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
lisdexamfetamine
Monitor Closely (3)lisdexamfetamine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

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

lisdexamfetamine and phenylephrine both decrease sedation. Use Caution/Monitor.
lofepramine
Monitor Closely (2)chlorpheniramine and lofepramine both increase sedation. Use Caution/Monitor.

lofepramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)lofepramine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
lofexidine
Monitor Closely (2)chlorpheniramine and lofexidine both increase sedation. Use Caution/Monitor.

lofexidine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
lonafarnib
Serious - Use Alternative (1)lonafarnib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with sensitive CYP3A substrates. If coadministration unavoidable, monitor for adverse reactions and reduce CYP3A substrate dose in accordance with product labeling.
loprazolam
Monitor Closely (2)loprazolam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

lorazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
lormetazepam
Monitor Closely (2)chlorpheniramine and lormetazepam both increase sedation. Use Caution/Monitor.

lormetazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
loxapine
Monitor Closely (2)chlorpheniramine and loxapine both increase sedation. Use Caution/Monitor.

loxapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
loxapine inhaled
Monitor Closely (2)loxapine inhaled increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and loxapine inhaled both increase sedation. Use Caution/Monitor.
lurasidone
Monitor Closely (1)lurasidone, chlorpheniramine. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Potential for increased CNS depressant effects when used concurrently; monitor for increased adverse effects and toxicity.
maprotiline
Monitor Closely (2)maprotiline increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and maprotiline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)maprotiline, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
marijuana
Monitor Closely (2)chlorpheniramine and marijuana both increase sedation. Use Caution/Monitor.

marijuana increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
melatonin
Monitor Closely (2)melatonin increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

meperidine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
meprobamate
Monitor Closely (2)meprobamate increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and meprobamate both increase sedation. Use Caution/Monitor.
metaproterenol
Monitor Closely (3)metaproterenol and phenylephrine both decrease sedation. Use Caution/Monitor.

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

metaproterenol and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
metaxalone
Monitor Closely (1)chlorpheniramine and metaxalone both increase sedation. Use Caution/Monitor.
methadone
Monitor Closely (2)chlorpheniramine and methadone both increase sedation. Use Caution/Monitor.

methadone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
methamphetamine
Monitor Closely (3)chlorpheniramine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

methamphetamine and phenylephrine both decrease sedation. Use Caution/Monitor.
methocarbamol
Monitor Closely (1)chlorpheniramine and methocarbamol both increase sedation. Use Caution/Monitor.
methoxyflurane
Serious - Use Alternative (1)methoxyflurane increases toxicity of phenylephrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.
methyldopa
Monitor Closely (1)methyldopa increases effects of phenylephrine by unknown mechanism. Use Caution/Monitor.
methylenedioxymethamphetamine
Monitor Closely (3)chlorpheniramine increases and methylenedioxymethamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

methylenedioxymethamphetamine and phenylephrine both decrease sedation. Use Caution/Monitor.
methylergonovine
Serious - Use Alternative (1)methylergonovine, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.
metoclopramide intranasal
Serious - Use Alternative (1)chlorpheniramine, metoclopramide intranasal. Either increases effects of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid use of metoclopramide intranasal or interacting drug, depending on importance of drug to patient.
midazolam
Monitor Closely (2)midazolam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and midazolam both increase sedation. Use Caution/Monitor.
midazolam intranasal
Monitor Closely (1)midazolam intranasal, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase the risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.
midodrine
Monitor Closely (3)midodrine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

midodrine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
mirtazapine
Monitor Closely (2)chlorpheniramine and mirtazapine both increase sedation. Use Caution/Monitor.

mirtazapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
mitotane
Monitor Closely (1)mitotane decreases levels of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.
modafinil
Monitor Closely (2)chlorpheniramine increases and modafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

modafinil and phenylephrine both decrease sedation. Use Caution/Monitor.
morphine
Monitor Closely (2)chlorpheniramine and morphine both increase sedation. Use Caution/Monitor.

morphine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
motherwort
Monitor Closely (2)chlorpheniramine and motherwort both increase sedation. Use Caution/Monitor.

motherwort increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
moxisylyte
Minor (1)moxisylyte, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
moxonidine
Monitor Closely (2)moxonidine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

nabilone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
nadolol
Monitor Closely (1)nadolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).
nalbuphine
Monitor Closely (2)nalbuphine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and nalbuphine both increase sedation. Use Caution/Monitor.
nettle
Minor (1)nettle increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. (High dose nettle; theoretical interaction) May enhance CNS depression.
norepinephrine
Monitor Closely (3)norepinephrine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

chlorpheniramine increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
nortriptyline
Monitor Closely (2)chlorpheniramine and nortriptyline both increase sedation. Use Caution/Monitor.

nortriptyline increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)nortriptyline, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
olanzapine
Monitor Closely (2)chlorpheniramine and olanzapine both increase sedation. Use Caution/Monitor.

olanzapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
olodaterol inhaled
Monitor Closely (1)phenylephrine and olodaterol inhaled both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Caution with coadministration of adrenergic drugs by any route because of additive sympathetic effects
olopatadine intranasal
Serious - Use Alternative (1)chlorpheniramine and olopatadine intranasal both increase sedation. Avoid or Use Alternate Drug. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.
opium tincture
Monitor Closely (2)chlorpheniramine and opium tincture both increase sedation. Use Caution/Monitor.

opium tincture increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
orphenadrine
Monitor Closely (1)chlorpheniramine and orphenadrine both increase sedation. Use Caution/Monitor.
oxazepam
Monitor Closely (2)chlorpheniramine and oxazepam both increase sedation. Use Caution/Monitor.

oxazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
oxycodone
Monitor Closely (2)oxycodone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and oxycodone both increase sedation. Use Caution/Monitor.
oxymetazoline topical
Monitor Closely (1)oxymetazoline topical and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
oxymorphone
Monitor Closely (2)oxymorphone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and oxymorphone both increase sedation. Use Caution/Monitor.
oxytocin
Monitor Closely (1)oxytocin increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor.
paliperidone
Monitor Closely (2)chlorpheniramine and paliperidone both increase sedation. Use Caution/Monitor.

paliperidone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
papaveretum
Monitor Closely (2)chlorpheniramine and papaveretum both increase sedation. Use Caution/Monitor.

papaveretum increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
papaverine
Monitor Closely (1)chlorpheniramine and papaverine both increase sedation. Use Caution/Monitor.
passion flower
Monitor Closely (1)passion flower increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.
pentazocine
Monitor Closely (2)chlorpheniramine and pentazocine both increase sedation. Use Caution/Monitor.

pentazocine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
pentobarbital
Monitor Closely (2)chlorpheniramine and pentobarbital both increase sedation. Use Caution/Monitor.

pentobarbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
perphenazine
Monitor Closely (3)perphenazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

perphenazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.

chlorpheniramine and perphenazine both increase sedation. Use Caution/Monitor.
phendimetrazine
Monitor Closely (3)chlorpheniramine increases and phendimetrazine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

phendimetrazine and phenylephrine both decrease sedation. Use Caution/Monitor.

phendimetrazine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
phenelzine
Contraindicated (1)phenelzine increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.Monitor Closely (1)phenelzine increases effects of chlorpheniramine by Other (see comment). Modify Therapy/Monitor Closely. Comment: Coadministration of phenelzine and antihistamines may result in additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .
phenobarbital
Monitor Closely (2)chlorpheniramine and phenobarbital both increase sedation. Use Caution/Monitor.

phenobarbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
phenoxybenzamine
Minor (1)phenoxybenzamine, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
phentermine
Monitor Closely (3)phentermine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

phentermine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
phentolamine
Minor (1)phentolamine, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
phenylephrine
Monitor Closely (1)chlorpheniramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
phenylephrine PO
Monitor Closely (1)chlorpheniramine increases and phenylephrine PO decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. .
pholcodine
Monitor Closely (2)pholcodine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

pimozide increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
pindolol
Monitor Closely (1)pindolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).
pirbuterol
Monitor Closely (3)chlorpheniramine increases and pirbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

pirbuterol and phenylephrine both decrease sedation. Use Caution/Monitor.

pirbuterol and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
prazosin
Minor (1)prazosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
pregabalin
Monitor Closely (1)pregabalin, chlorpheniramine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.
primidone
Monitor Closely (2)primidone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and primidone both increase sedation. Use Caution/Monitor.
procarbazine
Contraindicated (1)procarbazine increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
prochlorperazine
Monitor Closely (3)chlorpheniramine and prochlorperazine both increase sedation. Use Caution/Monitor.

prochlorperazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.

prochlorperazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
promazine
Monitor Closely (1)promazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
promethazine
Monitor Closely (3)promethazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

promethazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.
propofol
Monitor Closely (2)propofol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

propofol and chlorpheniramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)propofol increases levels of phenylephrine by decreasing metabolism. Contraindicated.
propranolol
Monitor Closely (1)propranolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).
propylhexedrine
Monitor Closely (3)phenylephrine and propylhexedrine both decrease sedation. Use Caution/Monitor.

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

phenylephrine and propylhexedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
protriptyline
Monitor Closely (2)chlorpheniramine and protriptyline both increase sedation. Use Caution/Monitor.

protriptyline increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)protriptyline, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
pseudoephedrine
Monitor Closely (1)phenylephrine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
quazepam
Monitor Closely (2)chlorpheniramine and quazepam both increase sedation. Use Caution/Monitor.

quazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
quetiapine
Monitor Closely (2)quetiapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and quetiapine both increase sedation. Use Caution/Monitor.
ramelteon
Monitor Closely (1)chlorpheniramine and ramelteon both increase sedation. Use Caution/Monitor.
rasagiline
Monitor Closely (1)rasagiline increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode.
ribociclib
Minor (1)ribociclib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
risperidone
Monitor Closely (2)chlorpheniramine and risperidone both increase sedation. Use Caution/Monitor.

risperidone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
rucaparib
Monitor Closely (1)rucaparib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.
safinamide
Monitor Closely (1)phenylephrine and safinamide both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Monitor patients for hypertension if safinamide is prescribed concomitantly with prescription or nonprescription sympathomimetics, including nasal, oral, or ophthalmic decongestants and cold remedies.
sage
Minor (2)sage increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.

chlorpheniramine and sage both increase sedation. Minor/Significance Unknown.
salmeterol
Monitor Closely (3)chlorpheniramine increases and salmeterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

salmeterol and phenylephrine both decrease sedation. Use Caution/Monitor.
scullcap
Monitor Closely (2)chlorpheniramine and scullcap both increase sedation. Use Caution/Monitor.

scullcap increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
secobarbital
Monitor Closely (2)secobarbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and secobarbital both increase sedation. Use Caution/Monitor.
selegiline
Monitor Closely (1)selegiline increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode.
selegiline transdermal
Contraindicated (1)selegiline transdermal increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
serdexmethylphenidate/dexmethylphenidate
Monitor Closely (2)serdexmethylphenidate/dexmethylphenidate and phenylephrine both decrease sedation. Use Caution/Monitor.

serdexmethylphenidate/dexmethylphenidate and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
sevoflurane
Monitor Closely (1)sevoflurane and chlorpheniramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)sevoflurane increases levels of phenylephrine by decreasing metabolism. Contraindicated.

sevoflurane increases toxicity of phenylephrine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.
shepherd's purse
Monitor Closely (2)chlorpheniramine and shepherd's purse both increase sedation. Use Caution/Monitor.

shepherd's purse increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
Siberian ginseng
Minor (1)Siberian ginseng increases effects of chlorpheniramine by pharmacodynamic synergism. Minor/Significance Unknown. May enhance CNS depression.
silodosin
Minor (1)silodosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
sodium oxybate
Serious - Use Alternative (1)chlorpheniramine, sodium oxybate. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.
solriamfetol
Monitor Closely (1)phenylephrine and solriamfetol both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
stiripentol
Monitor Closely (1)stiripentol, chlorpheniramine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.
sufentanil
Monitor Closely (2)sufentanil increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

tapentadol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
tazemetostat
Monitor Closely (1)tazemetostat will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
tecovirimat
Monitor Closely (1)tecovirimat will decrease the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.
temazepam
Monitor Closely (2)temazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and temazepam both increase sedation. Use Caution/Monitor.
terazosin
Minor (1)terazosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
terbutaline
Monitor Closely (3)terbutaline and phenylephrine both decrease sedation. Use Caution/Monitor.

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

chlorpheniramine increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thioridazine
Monitor Closely (3)chlorpheniramine and thioridazine both increase sedation. Use Caution/Monitor.

thioridazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.

thioridazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
thiothixene
Monitor Closely (2)chlorpheniramine and thiothixene both increase sedation. Use Caution/Monitor.

thiothixene increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
timolol
Monitor Closely (1)timolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).
topiramate
Monitor Closely (2)topiramate increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.

chlorpheniramine and topiramate both increase sedation. Modify Therapy/Monitor Closely.
tramadol
Monitor Closely (2)chlorpheniramine and tramadol both increase sedation. Use Caution/Monitor.

tramadol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
tranylcypromine
Contraindicated (1)tranylcypromine increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.Serious - Use Alternative (1)tranylcypromine increases effects of chlorpheniramine by Other (see comment). Avoid or Use Alternate Drug. Comment: Tranylcypromine should not be administered in combination with antihistamines because of potential additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .
trazodone
Monitor Closely (2)chlorpheniramine and trazodone both increase sedation. Use Caution/Monitor.

trazodone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)trazodone, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
triazolam
Monitor Closely (2)chlorpheniramine and triazolam both increase sedation. Use Caution/Monitor.

triazolam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
triclofos
Monitor Closely (2)chlorpheniramine and triclofos both increase sedation. Use Caution/Monitor.

triclofos increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
trifluoperazine
Monitor Closely (3)chlorpheniramine and trifluoperazine both increase sedation. Use Caution/Monitor.

trifluoperazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.

trifluoperazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
trimipramine
Monitor Closely (2)trimipramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and trimipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)trimipramine, phenylephrine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.
triprolidine
Monitor Closely (2)triprolidine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

chlorpheniramine and triprolidine both increase sedation. Use Caution/Monitor.
tucatinib
Serious - Use Alternative (1)tucatinib will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.
valerian
Monitor Closely (1)valerian increases effects of chlorpheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.
voxelotor
Serious - Use Alternative (1)voxelotor will increase the level or effect of chlorpheniramine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.
xylometazoline
Monitor Closely (3)chlorpheniramine increases and xylometazoline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

phenylephrine and xylometazoline both decrease sedation. Use Caution/Monitor.

phenylephrine and xylometazoline both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
yohimbe
Serious - Use Alternative (1)yohimbe, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
yohimbine
Monitor Closely (3)yohimbine and phenylephrine both decrease sedation. Use Caution/Monitor.

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

chlorpheniramine increases and yohimbine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
ziconotide
Monitor Closely (2)chlorpheniramine and ziconotide both increase sedation. Use Caution/Monitor.

ziconotide increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
ziprasidone
Monitor Closely (2)ziprasidone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

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

Frequency Not Defined

Hypertension

Hypotension

Palpitations

Reflex tachycardia

Severe peripheral and visceral vasoconstriction

Tachycardia

Confusion

Depression

Distress

Dizziness

Excitability

Euphoria

Fatigue

Headache

Insomnia

Irritability

Restlessness

Sedation

Tremor

Anorexia

Agranulocytosis

Hemolytic anemia

Thrombocytopenia

Thickening of bronchial secretions

Wheezing

Contraindications

Contraindicated in documented hypersensitivity; asthma attacks, narrow-angle glaucoma, symptomatic prostate hypertrophy, bladder-neck obstruction, and stenosing peptic ulcer

Cautions

Caution in elderly patients, hyperthyroidism, myocardial disease, bradycardia, partial heart block or severe arteriosclerosis when administering phenylephrine; in hypovolemia, phenylephrine use is not a substitute for replacement of blood, fluids and electrolytes, and plasma (promptly restore with loss); dilute IV and administer via large vein; extravasation precautions required

Chlorpheniramine may cause significant confusional symptoms; not for administration to premature or full-term neonates

Pregnancy & Lactation

Pregnancy Category: C

Lactation: excretion in milk unknown/contraindicated

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.

Mechanism of Action

Chlorpheniramine blocks muscle responses in histamine and acts as an antagonism of the constrictor effects of histamine on respiratory smooth muscle.

Phenylephrine is a vasoconstrictor and a decongestant that relieves symptoms resulting from irritation of upper respiratory tract tissue. It shrinks swollen mucous membranes, reduces nasal congestion and tissue hyperemia.

Pharmacokinetics

Chlorpheniramine

Vd: 4-7 L/kg (children); 6-12 L/kg (adults)
Protein binding: 33%
Half-life: 10-13 hr (children); 14-24 hr (adults)
Peak plasma time: 2-4 hr
Excretion: Urine

Phenylephrine

Onset of action: 15-30 min (nasal decongestant); 10-15 min (vasoconstriction)
Duration: < 4 hr (oral decongestant); 1-2 hr (blood pressure if IM); 15-20 min (blood pressure if given IV)
Absorption: Rapid (oral)
Vd: 26-61 L
Bioavailability: 38% (PO)
Half-life: 2-3 min (terminal phase)
Peak plasma time: 0.75-2 hr (PO)
Excretion: Urine

Images

No images available for this drug.

Patient Handout

A Patient Handout is not currently available for this monograph.

Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.

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Sections chlorpheniramine/phenylephrine
Dosing & Uses
Interactions
Adverse Effects
Warnings
Pregnancy
Pharmacology
Images
Patient Handout

chlorpheniramine/phenylephrine (OTC)

Dosing & Uses

Dosage Forms & Strengths

tablet

liquid

liquid (drops)

Nasal Congestion or Sneezing Due to Common Cold, Hay Fever, Allergic Rhinitis

Tablet

Liquid

Dosage Forms & Strengths

tablet

liquid

liquid (drops)

Nasal Congestion or Sneezing Due to Common Cold, Hay Fever, Allergic Rhinitis

Liquid (drops)

Liquid

tablet

Interactions

Interaction Checker

Contraindicated

Serious - Use Alternative

Significant - Monitor Closely

Minor

Contraindicated (7)

Serious - Use Alternative (44)

Monitor Closely (281)

Minor (22)

Adverse Effects

Frequency Not Defined

Warnings

Contraindications

Cautions

Pregnancy & Lactation

Pregnancy Categories

Pharmacology

Mechanism of Action

Pharmacokinetics

Chlorpheniramine

Phenylephrine

Images

Patient Handout

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