brompheniramine/dextromethorphan/phenylephrine (OTC)

Relief of Cold Symptoms

4 teaspoons (20 mL) PO q4hr; not to exceed 120 mL/24 hr

Relief of Cold Symptoms

<6 years

• Not recommended

6-12 years

• 2 teaspoons (10 mL) PO q4hr

>12 years

• 4 teaspoons (20 mL) PO q4hr

Contraindicated (11)

• 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 and dextromethorphan both increase serotonin levels. Contraindicated.
  
  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 and dextromethorphan both increase serotonin levels. Contraindicated.

• 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.
  
  procarbazine and dextromethorphan both increase serotonin levels. Contraindicated. Combination is contraindicated within 2 weeks of MAOI use.

• rasagiline

  rasagiline and dextromethorphan both increase serotonin levels. Contraindicated. Risk of psychosis episodes or bizarre behavior.

• selegiline transdermal

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

• safinamide

  dextromethorphan, safinamide. Other (see comment). Contraindicated. Comment: Coadministration of MAOIs and dextromethorphan has been reported to cause episodes of psychosis or bizarre behavior.

• selegiline

  selegiline and dextromethorphan both increase serotonin levels. Contraindicated.

• tranylcypromine

  tranylcypromine and dextromethorphan both increase serotonin levels. Contraindicated.
  
  tranylcypromine increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.

Serious - Use Alternative (59)

• amitriptyline

  amitriptyline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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 and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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.

• buspirone

  buspirone and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• cabergoline

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

• calcium/magnesium/potassium/sodium oxybates

  brompheniramine, calcium/magnesium/potassium/sodium oxybates. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation.

• citalopram

  citalopram and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. Combination may increase risk of serotonin syndrome or neuroleptic malignant syndrome-like reactions.

• clomipramine

  clomipramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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 and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• 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.

• desvenlafaxine

  dextromethorphan and desvenlafaxine both increase serotonin levels. Avoid or Use Alternate Drug.

• 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 and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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.

• duloxetine

  duloxetine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  duloxetine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• eluxadoline

  brompheniramine, 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.

• escitalopram

  escitalopram and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• 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.

• fluoxetine

  fluoxetine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  fluoxetine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• fluvoxamine

  fluvoxamine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• grapefruit

  grapefruit will increase the level or effect of dextromethorphan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• imipramine

  imipramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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 brompheniramine by Other (see comment). Avoid or Use Alternate Drug. Comment: Isocarboxazid should not be administered in combination with antihistamines because of potential additive CNS depressant effects. MAO inhibitors also prolong and intensify anticholinergic effects of antihistamines. .

• levomilnacipran

  levomilnacipran and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• isoflurane

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

• linezolid

  linezolid and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. Linezolid may increase serotonin as a result of MAO-A inhibition. If linezolid must be administered, discontinue serotonergic drug immediately and monitor for CNS toxicity. Serotonergic therapy may be resumed 24 hours after last linezolid dose or after 2 weeks of monitoring, whichever comes first.

• lofepramine

  lofepramine, 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.
  
  lofepramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• lorcaserin

  dextromethorphan and lorcaserin both increase serotonin levels. Avoid or Use Alternate Drug.

• 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.

• maprotiline

  maprotiline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• memantine

  memantine, dextromethorphan. Either increases toxicity of the other by pharmacodynamic synergism. Contraindicated.

• meperidine

  dextromethorphan and meperidine both increase serotonin levels. Avoid or Use Alternate Drug.

• methoxyflurane

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

• methylene blue

  methylene blue and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. Methylene blue may increase serotonin as a result of MAO-A inhibition. If methylene blue must be administered, discontinue serotonergic drug immediately and monitor for CNS toxicity. Serotonergic therapy may be resumed 24 hours after last methylene blue dose or after 2 weeks of monitoring, whichever comes first.

• methylergonovine

  methylergonovine, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.

• metoclopramide intranasal

  brompheniramine, metoclopramide intranasal. Either increases effects of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid use of metoclopramide intranasal or interacting drug, depending on importance of drug to patient.

• milnacipran

  milnacipran and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• nefazodone

  nefazodone and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• nortriptyline

  nortriptyline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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

  brompheniramine and olopatadine intranasal both increase sedation. Avoid or Use Alternate Drug. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.

• paroxetine

  paroxetine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  paroxetine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• pitolisant

  brompheniramine decreases effects of pitolisant by Other (see comment). Avoid or Use Alternate Drug. Comment: Pitolisant increases histamine levels in the brain; therefore, H1 receptor antagonists that cross the blood-brain barrier may reduce the efficacy of pitolisant.

• 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.
  
  protriptyline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• selegiline transdermal

  selegiline transdermal and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• selinexor

  selinexor, brompheniramine. unspecified interaction mechanism. Avoid or Use Alternate Drug. Patients treated with selinexor may experience neurological toxicities. Avoid taking selinexor with other medications that may cause dizziness or confusion.

• sertraline

  sertraline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• St John's Wort

  dextromethorphan and St John's Wort both increase serotonin levels. Avoid or Use Alternate Drug.

• 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

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

• trazodone

  trazodone and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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 and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• venlafaxine

  venlafaxine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.
  
  venlafaxine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• vilazodone

  dextromethorphan, vilazodone. Either increases toxicity of the other by serotonin levels. Avoid or Use Alternate Drug. Concomitant therapy should be discontinued immediately if signs or symptoms of serotonin syndrome emerge and supportive symptomatic treatment should be initiated. .

Monitor Closely (318)

• 5-HTP

  5-HTP and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• abiraterone

  abiraterone increases levels of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Avoid coadministration of abiraterone with substrates of CYP2D6. If alternative therapy cannot be used, exercise caution and consider a dose reduction of the CYP2D6 substrate.

• acrivastine

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

• alfentanil

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

• almotriptan

  almotriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• alprazolam

  brompheniramine 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

  brompheniramine 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 brompheniramine both increase sedation. Use Caution/Monitor.

• amitriptyline

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

• amphetamine

  amphetamine, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when amphemtamines are coadministered with dextromethorphan. .

• apomorphine

  brompheniramine 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

  brompheniramine 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.
  
  dextromethorphan, aripiprazole. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  brompheniramine and aripiprazole both increase sedation. Use Caution/Monitor.

• armodafinil

  brompheniramine 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.

• artemether/lumefantrine

  artemether/lumefantrine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• asenapine

  dextromethorphan, asenapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  asenapine and brompheniramine 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.

• bupropion

  bupropion will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• asenapine transdermal

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

• avapritinib

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

• baclofen

  brompheniramine 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

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

• benperidol

  brompheniramine 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

  benzhydrocodone/acetaminophen and brompheniramine both increase sedation. Use Caution/Monitor.

• benzphetamine

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

• benzphetamine

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

• brexanolone

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

• brexpiprazole

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

• brimonidine

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

• brivaracetam

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

• bromocriptine

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

• brompheniramine

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

• buprenorphine

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

• buprenorphine buccal

  brompheniramine 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

  buprenorphine subdermal implant and brompheniramine both increase sedation. Use Caution/Monitor.

• butabarbital

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

• buprenorphine transdermal

  buprenorphine transdermal and brompheniramine both increase sedation. Use Caution/Monitor.

• butabarbital

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

• butalbital

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

• butorphanol

  brompheniramine 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

  brompheniramine 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

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

• cariprazine

  dextromethorphan, cariprazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• carisoprodol

  brompheniramine 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, brompheniramine. Either increases effects of the other by sedation. Use Caution/Monitor.

• chloral hydrate

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

• chlordiazepoxide

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

• chlorpheniramine

  chlorpheniramine 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.

• chlorpromazine

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

• chlorzoxazone

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

• cinnarizine

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

• cinnarizine

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

• clemastine

  brompheniramine 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

  brompheniramine, clobazam. Other (see comment). Use Caution/Monitor. Comment: Concomitant administration can increase the potential for CNS effects (e.g., increased sedation or respiratory depression).
  
  clobazam will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Lower doses of drugs metabolized by CYP2D6 may be required when used concomitantly.

• clomipramine

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

• clozapine

  dextromethorphan, clozapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• clomipramine

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

• clonazepam

  brompheniramine 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

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

• cocaine topical

  cocaine topical and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• codeine

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

• cyclizine

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

• cyclobenzaprine

  brompheniramine 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.

• cyproheptadine

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

• dantrolene

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

• daridorexant

  brompheniramine 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 brompheniramine both increase sedation. Use Caution/Monitor.

• desipramine

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

• desvenlafaxine

  desvenlafaxine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Desvenlafaxine inhibits CYP2D6; with higher desvenlafaxine doses (ie, 400 mg) decrease the CYP2D6 substrate dose by up to 50%; no dosage adjustment needed with desvenlafaxine doses <100 mg

• deutetrabenazine

  brompheniramine 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.

• dexchlorpheniramine

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

• dexfenfluramine

  dexfenfluramine and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
  
  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.
  
  brompheniramine increases and dexfenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• dexmedetomidine

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

• dextroamphetamine

  dextroamphetamine, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when amphemtamines are coadministered with dextromethorphan. .

• dexmethylphenidate

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

• dextroamphetamine transdermal

  dextromethorphan, dextroamphetamine transdermal. Either increases effects of the other by serotonin levels. Modify Therapy/Monitor Closely. Initiate with lower doses and monitor for signs and symptoms of serotonin syndrome, particularly during initiation or dosage increase. If serotonin syndrome occurs, discontinue dextroamphetamine transdermal and concomitant serotonergic drug(s).
  
  dextroamphetamine transdermal, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when amphemtamines are coadministered with dextromethorphan. .

• dextromoramide

  brompheniramine 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

  brompheniramine 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

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

• diethylpropion

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

• difelikefalin

  difelikefalin and brompheniramine 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.
  
  brompheniramine and difenoxin hcl both increase sedation. Use Caution/Monitor.

• dihydroergotamine

  dextromethorphan and dihydroergotamine both increase serotonin levels. Modify Therapy/Monitor Closely.

• dihydroergotamine intranasal

  dextromethorphan and dihydroergotamine intranasal both increase serotonin levels. Modify Therapy/Monitor Closely.

• dimenhydrinate

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

• diphenhydramine

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

• diphenoxylate hcl

  brompheniramine 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

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

• dobutamine

  brompheniramine 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, brompheniramine. 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

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

• dopexamine

  brompheniramine 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

  brompheniramine 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

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

• doxylamine

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

• droperidol

  brompheniramine 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

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

• eletriptan

  eletriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• ephedrine

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

• ephedrine

  ephedrine and phenylephrine both decrease sedation. Use Caution/Monitor.
  
  ephedrine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  ephedrine, phenylephrine. Either increases effects of the other by pharmacodynamic synergism. 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.
  
  brompheniramine 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

  brompheniramine 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.

• ergotamine

  dextromethorphan and ergotamine both increase serotonin levels. Modify Therapy/Monitor Closely.

• esketamine intranasal

  esketamine intranasal, brompheniramine. 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.
  
  brompheniramine and estazolam both increase sedation. Use Caution/Monitor.

• ethanol

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

• etomidate

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

• fenfluramine

  fenfluramine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  fenfluramine, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Coadministration with drugs that increase serotoninergic effects may increase the risk of serotonin syndrome.
  
  dextromethorphan and fenfluramine both increase serotonin levels. Modify Therapy/Monitor Closely.
  
  fenfluramine and phenylephrine both decrease sedation. Use Caution/Monitor.

• fenfluramine

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

• fluphenazine

  dextromethorphan, fluphenazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• fentanyl

  fentanyl, brompheniramine. 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 and brompheniramine both increase sedation. Use Caution/Monitor.

• fentanyl intranasal

  fentanyl intranasal, brompheniramine. 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 and brompheniramine both increase sedation. Use Caution/Monitor.

• fentanyl iontophoretic transdermal system

  fentanyl iontophoretic transdermal system and brompheniramine both increase sedation. Use Caution/Monitor.

• fentanyl transdermal

  fentanyl transdermal, brompheniramine. 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 and brompheniramine both increase sedation. Use Caution/Monitor.

• fentanyl transmucosal

  fentanyl transmucosal, brompheniramine. 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

  brompheniramine 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.
  
  brompheniramine 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

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

• formoterol

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

• frovatriptan

  frovatriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• gabapentin

  gabapentin, brompheniramine. 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.

• gepirone

  gepirone and dextromethorphan both increase serotonin levels. Use Caution/Monitor. Monitor for symptoms of serotonin syndrome when gepirone is used gepirone with other drugs that may affect the serotonergic neurotransmitter systems. If serotonin syndrome occurs, consider discontinue gepirone and/or concomitant serotonergic drug.

• haloperidol

  haloperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dextromethorphan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• gabapentin enacarbil

  gabapentin enacarbil, brompheniramine. 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.

• iloperidone

  dextromethorphan, iloperidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• ganaxolone

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

• glycopyrronium tosylate topical

  glycopyrronium tosylate topical, brompheniramine. 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 brompheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• haloperidol

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

• hawthorn

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

• hops

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

• hyaluronidase

  brompheniramine 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

  brompheniramine 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

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

• iloperidone

  brompheniramine 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.

• imipramine

  brompheniramine 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.

• isoniazid

  dextromethorphan and isoniazid both increase serotonin levels. Modify Therapy/Monitor Closely.

• L-tryptophan

  dextromethorphan and L-tryptophan both increase serotonin levels. Modify Therapy/Monitor Closely.

• isoproterenol

  brompheniramine 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.

• kava

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

• ketamine

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

• ketotifen, ophthalmic

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

• lasmiditan

  lasmiditan, brompheniramine. 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.

• letermovir

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

• 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, brompheniramine. 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.

• levalbuterol

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

• lisdexamfetamine

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

• lithium

  dextromethorphan and lithium both increase serotonin levels. Modify Therapy/Monitor Closely.

• lofepramine

  brompheniramine 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

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

• lorazepam

  brompheniramine 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

  brompheniramine 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

  dextromethorphan, loxapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  loxapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and loxapine both increase sedation. Use Caution/Monitor.

• loxapine inhaled

  loxapine inhaled increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dextromethorphan, loxapine inhaled. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  brompheniramine and loxapine inhaled both increase sedation. Use Caution/Monitor.

• lsd

  dextromethorphan and lsd both increase serotonin levels. Modify Therapy/Monitor Closely.

• lurasidone

  lurasidone, brompheniramine. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Potential for increased CNS depressant effects when used concurrently; monitor for increased adverse effects and toxicity.

• lumefantrine

  lumefantrine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• lurasidone

  dextromethorphan, lurasidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• maprotiline

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

• maprotiline

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

• marijuana

  brompheniramine 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

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

• meperidine

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

• metaproterenol

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

• metaxalone

  brompheniramine 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

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

• methocarbamol

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

• methyldopa

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

• methylenedioxymethamphetamine

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

• midazolam

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

• midazolam intranasal

  midazolam intranasal, brompheniramine. 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

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

• mirtazapine

  dextromethorphan and mirtazapine both increase serotonin levels. Modify Therapy/Monitor Closely.
  
  mirtazapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and mirtazapine both increase sedation. Use Caution/Monitor.

• modafinil

  brompheniramine 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.

• molindone

  dextromethorphan, molindone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• morphine

  dextromethorphan and morphine both increase serotonin levels. Modify Therapy/Monitor Closely.
  
  brompheniramine 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

  brompheniramine 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.

• naratriptan

  naratriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• moxonidine

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

• nabilone

  brompheniramine 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

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

• nortriptyline

  brompheniramine 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

  brompheniramine 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.
  
  dextromethorphan, olanzapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• 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

• paliperidone

  dextromethorphan, paliperidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• opium tincture

  brompheniramine 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

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

• oxazepam

  brompheniramine 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

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

  brompheniramine 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

  brompheniramine 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.

• panobinostat

  panobinostat will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Panobinostat can increase the levels and effects of sensitive CYP2D6 substrates or those with a narrow therapeutic index CYP2D6.

• papaveretum

  brompheniramine 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

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

• pazopanib

  pazopanib increases levels of dextromethorphan by decreasing metabolism. Use Caution/Monitor.

• peginterferon alfa 2b

  peginterferon alfa 2b, dextromethorphan. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.

• pentazocine

  dextromethorphan and pentazocine both increase serotonin levels. Modify Therapy/Monitor Closely.
  
  pentazocine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• passion flower

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

• perphenazine

  dextromethorphan, perphenazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• pentazocine

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

• pentobarbital

  brompheniramine 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.

• perampanel

  perampanel and brompheniramine 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.

• perphenazine

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

• phendimetrazine

  brompheniramine 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 brompheniramine 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

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

• phentermine

  phentermine and phenylephrine both decrease sedation. Use Caution/Monitor.
  
  brompheniramine 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

  brompheniramine 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

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

• pholcodine

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

• pimavanserin

  dextromethorphan, pimavanserin. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• pimozide

  dextromethorphan, pimozide. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  brompheniramine 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

  pindolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).

• quetiapine

  dextromethorphan, quetiapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• pirbuterol

  brompheniramine 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, brompheniramine. 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.
  
  brompheniramine and primidone both increase sedation. Use Caution/Monitor.

• prochlorperazine

  brompheniramine 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

  brompheniramine 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 brompheniramine 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

  brompheniramine 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

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

• pseudoephedrine

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

• quazepam

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

• quinidine

  quinidine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• ramelteon

  brompheniramine 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

  brompheniramine 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.
  
  dextromethorphan, risperidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• rizatriptan

  rizatriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• 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.

• rolapitant

  rolapitant will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor for adverse reactions when unable to avoid coadministration with narrow therapeutic index CYP2D6 substrates.

• SAMe

  dextromethorphan and SAMe both increase serotonin levels. Modify Therapy/Monitor Closely.

• salmeterol

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

• salmeterol

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

• scullcap

  brompheniramine 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.
  
  brompheniramine 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 brompheniramine 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

  brompheniramine 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.

• sufentanil

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

• sufentanil

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

• sumatriptan

  sumatriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• sumatriptan intranasal

  sumatriptan intranasal and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• tapentadol

  brompheniramine 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.

• temazepam

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

• terbutaline

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

• thioridazine

  brompheniramine 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

  dextromethorphan, thiothixene. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  thiothixene increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and thiothixene both increase sedation. Use Caution/Monitor.

• timolol

  timolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).

• tramadol

  dextromethorphan and tramadol both increase serotonin levels. Modify Therapy/Monitor Closely.

• topiramate

  brompheniramine 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

  brompheniramine 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

  brompheniramine 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

  brompheniramine 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

  brompheniramine 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

  dextromethorphan, trifluoperazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  brompheniramine 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.
  
  brompheniramine and trimipramine both increase sedation. Use Caution/Monitor.

• ziprasidone

  dextromethorphan, ziprasidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• triprolidine

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

• valerian

  valerian increases effects of brompheniramine 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

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

• ziconotide

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

• zolmitriptan

  zolmitriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• zotepine

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

Minor (36)

• alfuzosin

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

• amiodarone

  amiodarone will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• asenapine

  asenapine, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
  
  asenapine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• ashwagandha

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

• celecoxib

  celecoxib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• brimonidine

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

• chloroquine

  chloroquine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• cimetidine

  cimetidine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• darifenacin

  darifenacin will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• desmopressin

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

• diphenhydramine

  diphenhydramine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• doxazosin

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

• dronedarone

  dronedarone will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• eucalyptus

  eucalyptus increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.
  
  brompheniramine and eucalyptus both increase sedation. Minor/Significance Unknown.

• haloperidol

  haloperidol will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• imatinib

  imatinib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• maraviroc

  maraviroc will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• marijuana

  marijuana will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• moxisylyte

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

• nettle

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

• nilotinib

  nilotinib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• parecoxib

  parecoxib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• perphenazine

  perphenazine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• 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.

• propafenone

  propafenone will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• quinacrine

  quinacrine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• ranolazine

  ranolazine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• ritonavir

  ritonavir will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• sage

  sage increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.
  
  brompheniramine and sage both increase sedation. Minor/Significance Unknown.

• Siberian ginseng

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

• sertraline

  sertraline will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• 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.

• thioridazine

  thioridazine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• 5-HTP

  Monitor Closely (1)5-HTP and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• abiraterone

  Monitor Closely (1)abiraterone increases levels of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Avoid coadministration of abiraterone with substrates of CYP2D6. If alternative therapy cannot be used, exercise caution and consider a dose reduction of the CYP2D6 substrate.

• acrivastine

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

• albuterol

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

• alfentanil

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

• alfuzosin

  Minor (1)alfuzosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.

• almotriptan

  Monitor Closely (1)almotriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• alprazolam

  Monitor Closely (2)brompheniramine 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)brompheniramine 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.

• amiodarone

  Minor (1)amiodarone will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• amisulpride

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

• amitriptyline

  Monitor Closely (2)brompheniramine and amitriptyline both increase sedation. Use Caution/Monitor.
  
  amitriptyline increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (2)amitriptyline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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 (2)amobarbital increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine 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.
  
  brompheniramine and amoxapine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)amoxapine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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.

• amphetamine

  Monitor Closely (1)amphetamine, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when amphemtamines are coadministered with dextromethorphan. .

• apomorphine

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

• arformoterol

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

• aripiprazole

  Monitor Closely (3)aripiprazole increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dextromethorphan, aripiprazole. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  brompheniramine and aripiprazole both increase sedation. Use Caution/Monitor.

• armodafinil

  Monitor Closely (2)brompheniramine 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.

• artemether/lumefantrine

  Monitor Closely (1)artemether/lumefantrine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• asenapine

  Monitor Closely (2)dextromethorphan, asenapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  asenapine and brompheniramine both increase sedation. Use Caution/Monitor.Minor (2)asenapine, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
  
  asenapine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• asenapine transdermal

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

• ashwagandha

  Minor (1)ashwagandha increases effects of brompheniramine 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 brompheniramine 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 brompheniramine both increase sedation. Use Caution/Monitor.

• baclofen

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

• belladonna and opium

  Monitor Closely (2)brompheniramine 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.

• benperidol

  Monitor Closely (2)brompheniramine 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

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

• benzphetamine

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

• brexanolone

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

• brexpiprazole

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

• brimonidine

  Monitor Closely (1)brimonidine and brompheniramine both increase sedation. Use Caution/Monitor.Minor (1)brimonidine increases effects of brompheniramine by pharmacodynamic synergism. Minor/Significance Unknown. Increased CNS depression.

• brivaracetam

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

• buprenorphine

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

• buprenorphine buccal

  Monitor Closely (2)brompheniramine 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

  Monitor Closely (1)buprenorphine subdermal implant and brompheniramine both increase sedation. Use Caution/Monitor.

• buprenorphine transdermal

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

• bupropion

  Monitor Closely (1)bupropion will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• buspirone

  Serious - Use Alternative (1)buspirone and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• butabarbital

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

• butorphanol

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

• cariprazine

  Monitor Closely (1)dextromethorphan, cariprazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• carisoprodol

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

• celecoxib

  Minor (1)celecoxib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• cenobamate

  Monitor Closely (1)cenobamate, brompheniramine. Either increases effects of the other by sedation. Use Caution/Monitor.

• chloral hydrate

  Monitor Closely (2)brompheniramine 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)brompheniramine 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.

• chloroquine

  Minor (1)chloroquine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• chlorpheniramine

  Monitor Closely (2)chlorpheniramine 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.

• chlorpromazine

  Monitor Closely (3)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.
  
  brompheniramine and chlorpromazine both increase sedation. Use Caution/Monitor.

• chlorzoxazone

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

• cimetidine

  Minor (1)cimetidine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• cinnarizine

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

• citalopram

  Serious - Use Alternative (1)citalopram and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. Combination may increase risk of serotonin syndrome or neuroleptic malignant syndrome-like reactions.

• clemastine

  Monitor Closely (2)brompheniramine 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 (2)brompheniramine, clobazam. Other (see comment). Use Caution/Monitor. Comment: Concomitant administration can increase the potential for CNS effects (e.g., increased sedation or respiratory depression).
  
  clobazam will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Lower doses of drugs metabolized by CYP2D6 may be required when used concomitantly.

• clomipramine

  Monitor Closely (2)brompheniramine 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 (2)clomipramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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)brompheniramine 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)brompheniramine 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 (3)clozapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and clozapine both increase sedation. Use Caution/Monitor.
  
  dextromethorphan, clozapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• cocaine topical

  Monitor Closely (1)cocaine topical and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• codeine

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

• cyclizine

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

• cyclobenzaprine

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

• cyproheptadine

  Monitor Closely (2)brompheniramine 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.

• dantrolene

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

• daridorexant

  Monitor Closely (1)brompheniramine and daridorexant both increase sedation. Modify Therapy/Monitor Closely. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment.

• darifenacin

  Minor (1)darifenacin will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• desflurane

  Monitor Closely (1)desflurane and brompheniramine 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)desipramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and desipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)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.
  
  desipramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• desmopressin

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

• desvenlafaxine

  Monitor Closely (1)desvenlafaxine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Desvenlafaxine inhibits CYP2D6; with higher desvenlafaxine doses (ie, 400 mg) decrease the CYP2D6 substrate dose by up to 50%; no dosage adjustment needed with desvenlafaxine doses <100 mgSerious - Use Alternative (1)dextromethorphan and desvenlafaxine both increase serotonin levels. Avoid or Use Alternate Drug.

• deutetrabenazine

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

• dexfenfluramine

  Monitor Closely (4)dexfenfluramine and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.
  
  dexfenfluramine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  brompheniramine increases and dexfenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dexfenfluramine and phenylephrine both decrease sedation. Use Caution/Monitor.

• dexmedetomidine

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

• dexmethylphenidate

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

• dextroamphetamine

  Monitor Closely (4)dextroamphetamine and phenylephrine both decrease sedation. Use Caution/Monitor.
  
  brompheniramine increases and dextroamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dextroamphetamine, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when amphemtamines are coadministered with dextromethorphan. .
  
  dextroamphetamine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• dextroamphetamine transdermal

  Monitor Closely (2)dextroamphetamine transdermal, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when amphemtamines are coadministered with dextromethorphan. .
  
  dextromethorphan, dextroamphetamine transdermal. Either increases effects of the other by serotonin levels. Modify Therapy/Monitor Closely. Initiate with lower doses and monitor for signs and symptoms of serotonin syndrome, particularly during initiation or dosage increase. If serotonin syndrome occurs, discontinue dextroamphetamine transdermal and concomitant serotonergic drug(s).

• dextromoramide

  Monitor Closely (2)brompheniramine 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)brompheniramine 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)brompheniramine and diazepam both increase sedation. Use Caution/Monitor.

• diazepam intranasal

  Monitor Closely (1)diazepam intranasal, brompheniramine. 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.
  
  brompheniramine increases and diethylpropion decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  diethylpropion and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.

• difelikefalin

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

• difenoxin hcl

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

• dihydroergotamine

  Monitor Closely (1)dextromethorphan and dihydroergotamine both increase serotonin levels. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)dihydroergotamine, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.

• dihydroergotamine intranasal

  Monitor Closely (1)dextromethorphan and dihydroergotamine intranasal both increase serotonin levels. Modify Therapy/Monitor Closely.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.
  
  brompheniramine and dimenhydrinate both increase sedation. Use Caution/Monitor.

• diphenhydramine

  Monitor Closely (2)brompheniramine and diphenhydramine both increase sedation. Use Caution/Monitor.
  
  diphenhydramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)diphenhydramine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• diphenoxylate hcl

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

• dobutamine

  Monitor Closely (3)brompheniramine 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, brompheniramine. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.

• dopamine

  Monitor Closely (3)brompheniramine 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)brompheniramine 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)brompheniramine 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.
  
  brompheniramine and doxepin both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)doxepin and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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)brompheniramine and doxylamine both increase sedation. Use Caution/Monitor.

• dronedarone

  Minor (1)dronedarone will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• droperidol

  Monitor Closely (2)brompheniramine 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

• duloxetine

  Serious - Use Alternative (2)duloxetine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  duloxetine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• eletriptan

  Monitor Closely (1)eletriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• eluxadoline

  Serious - Use Alternative (1)brompheniramine, 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.

• ephedrine

  Monitor Closely (4)ephedrine, phenylephrine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.
  
  brompheniramine increases and ephedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  ephedrine and phenylephrine both decrease sedation. 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.
  
  brompheniramine increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  epinephrine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. 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)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.
  
  brompheniramine increases and epinephrine racemic decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• ergoloid mesylates

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

• ergotamine

  Monitor Closely (1)dextromethorphan and ergotamine both increase serotonin levels. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)ergotamine, phenylephrine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.

• escitalopram

  Serious - Use Alternative (1)escitalopram and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• esketamine intranasal

  Monitor Closely (1)esketamine intranasal, brompheniramine. 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.
  
  brompheniramine and estazolam both increase sedation. Use Caution/Monitor.

• ethanol

  Monitor Closely (2)brompheniramine and ethanol both increase sedation. Use Caution/Monitor.
  
  ethanol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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 brompheniramine 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.
  
  brompheniramine and eucalyptus both increase sedation. Minor/Significance Unknown.

• fenfluramine

  Monitor Closely (5)fenfluramine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.
  
  fenfluramine, dextromethorphan. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Coadministration with drugs that increase serotoninergic effects may increase the risk of serotonin syndrome.
  
  brompheniramine increases and fenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dextromethorphan and fenfluramine both increase serotonin levels. Modify Therapy/Monitor Closely.
  
  fenfluramine and phenylephrine both decrease sedation. Use Caution/Monitor.

• fentanyl

  Monitor Closely (2)fentanyl, brompheniramine. 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 and brompheniramine both increase sedation. Use Caution/Monitor.

• fentanyl intranasal

  Monitor Closely (2)fentanyl intranasal, brompheniramine. 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 and brompheniramine both increase sedation. Use Caution/Monitor.

• fentanyl iontophoretic transdermal system

  Monitor Closely (1)fentanyl iontophoretic transdermal system and brompheniramine both increase sedation. Use Caution/Monitor.

• fentanyl transdermal

  Monitor Closely (2)fentanyl transdermal, brompheniramine. 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 and brompheniramine both increase sedation. Use Caution/Monitor.

• fentanyl transmucosal

  Monitor Closely (1)fentanyl transmucosal, brompheniramine. 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

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

• fluoxetine

  Serious - Use Alternative (2)fluoxetine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  fluoxetine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• fluphenazine

  Monitor Closely (4)brompheniramine and fluphenazine both increase sedation. Use Caution/Monitor.
  
  fluphenazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dextromethorphan, fluphenazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  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)flurazepam increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and flurazepam both increase sedation. Use Caution/Monitor.

• fluvoxamine

  Serious - Use Alternative (1)fluvoxamine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• formoterol

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

• frovatriptan

  Monitor Closely (1)frovatriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• gabapentin

  Monitor Closely (1)gabapentin, brompheniramine. 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, brompheniramine. 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)brompheniramine and ganaxolone both increase sedation. Use Caution/Monitor.

• gepirone

  Monitor Closely (1)gepirone and dextromethorphan both increase serotonin levels. Use Caution/Monitor. Monitor for symptoms of serotonin syndrome when gepirone is used gepirone with other drugs that may affect the serotonergic neurotransmitter systems. If serotonin syndrome occurs, consider discontinue gepirone and/or concomitant serotonergic drug.

• glycopyrronium tosylate topical

  Monitor Closely (1)glycopyrronium tosylate topical, brompheniramine. 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 brompheniramine by pharmacodynamic synergism. Use Caution/Monitor. May enhance CNS depression.

• grapefruit

  Serious - Use Alternative (1)grapefruit will increase the level or effect of dextromethorphan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• haloperidol

  Monitor Closely (3)haloperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and haloperidol both increase sedation. Use Caution/Monitor.
  
  dextromethorphan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).Minor (1)haloperidol will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• hawthorn

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

• hops

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

• hyaluronidase

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

• iloperidone

  Monitor Closely (3)brompheniramine 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.
  
  dextromethorphan, iloperidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• imatinib

  Minor (1)imatinib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• imipramine

  Monitor Closely (2)brompheniramine 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 (2)imipramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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 (2)isocarboxazid increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
  
  isocarboxazid and dextromethorphan both increase serotonin levels. Contraindicated.Serious - Use Alternative (1)isocarboxazid increases effects of brompheniramine 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.

• isoniazid

  Monitor Closely (1)dextromethorphan and isoniazid both increase serotonin levels. Modify Therapy/Monitor Closely.

• isoproterenol

  Monitor Closely (3)brompheniramine 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.

• kava

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

• ketamine

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

• ketotifen, ophthalmic

  Monitor Closely (2)brompheniramine 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.

• L-tryptophan

  Monitor Closely (1)dextromethorphan and L-tryptophan both increase serotonin levels. Modify Therapy/Monitor Closely.

• lasmiditan

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

• letermovir

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

• levalbuterol

  Monitor Closely (3)brompheniramine 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.

• levomilnacipran

  Serious - Use Alternative (1)levomilnacipran and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• levorphanol

  Monitor Closely (2)levorphanol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine 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.Serious - Use Alternative (1)linezolid and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. Linezolid may increase serotonin as a result of MAO-A inhibition. If linezolid must be administered, discontinue serotonergic drug immediately and monitor for CNS toxicity. Serotonergic therapy may be resumed 24 hours after last linezolid dose or after 2 weeks of monitoring, whichever comes first.

• lisdexamfetamine

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

• lithium

  Monitor Closely (1)dextromethorphan and lithium both increase serotonin levels. Modify Therapy/Monitor Closely.

• lofepramine

  Monitor Closely (2)brompheniramine 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 (2)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.
  
  lofepramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• lofexidine

  Monitor Closely (2)brompheniramine 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

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

• lorazepam

  Monitor Closely (2)brompheniramine 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.

• lorcaserin

  Serious - Use Alternative (1)dextromethorphan and lorcaserin both increase serotonin levels. Avoid or Use Alternate Drug.

• lormetazepam

  Monitor Closely (2)brompheniramine 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 (3)dextromethorphan, loxapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  loxapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and loxapine both increase sedation. Use Caution/Monitor.

• loxapine inhaled

  Monitor Closely (3)loxapine inhaled increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dextromethorphan, loxapine inhaled. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  brompheniramine and loxapine inhaled both increase sedation. Use Caution/Monitor.

• lsd

  Monitor Closely (1)dextromethorphan and lsd both increase serotonin levels. Modify Therapy/Monitor Closely.

• lumefantrine

  Monitor Closely (1)lumefantrine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• lurasidone

  Monitor Closely (2)dextromethorphan, lurasidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  lurasidone, brompheniramine. 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)brompheniramine and maprotiline both increase sedation. Use Caution/Monitor.
  
  maprotiline increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (2)maprotiline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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.

• maraviroc

  Minor (1)maraviroc will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• marijuana

  Monitor Closely (2)brompheniramine 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.Minor (1)marijuana will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• melatonin

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

• memantine

  Serious - Use Alternative (1)memantine, dextromethorphan. Either increases toxicity of the other by pharmacodynamic synergism. Contraindicated.

• meperidine

  Monitor Closely (2)brompheniramine 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.Serious - Use Alternative (1)dextromethorphan and meperidine both increase serotonin levels. Avoid or Use Alternate Drug.

• meprobamate

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

• metaproterenol

  Monitor Closely (3)brompheniramine increases and metaproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  metaproterenol and phenylephrine both decrease sedation. 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)brompheniramine and metaxalone both increase sedation. Use Caution/Monitor.

• methadone

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

• methamphetamine

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

• methocarbamol

  Monitor Closely (1)brompheniramine 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.

• methylene blue

  Serious - Use Alternative (1)methylene blue and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug. Methylene blue may increase serotonin as a result of MAO-A inhibition. If methylene blue must be administered, discontinue serotonergic drug immediately and monitor for CNS toxicity. Serotonergic therapy may be resumed 24 hours after last methylene blue dose or after 2 weeks of monitoring, whichever comes first.

• methylenedioxymethamphetamine

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

• midazolam intranasal

  Monitor Closely (1)midazolam intranasal, brompheniramine. 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.
  
  brompheniramine 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.

• milnacipran

  Serious - Use Alternative (1)milnacipran and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• mirtazapine

  Monitor Closely (3)dextromethorphan and mirtazapine both increase serotonin levels. Modify Therapy/Monitor Closely.
  
  mirtazapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and mirtazapine both increase sedation. Use Caution/Monitor.

• modafinil

  Monitor Closely (2)brompheniramine 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.

• molindone

  Monitor Closely (1)dextromethorphan, molindone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• morphine

  Monitor Closely (3)dextromethorphan and morphine both increase serotonin levels. Modify Therapy/Monitor Closely.
  
  brompheniramine 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)brompheniramine 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.
  
  brompheniramine and moxonidine both increase sedation. Use Caution/Monitor.

• nabilone

  Monitor Closely (2)brompheniramine 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.
  
  brompheniramine and nalbuphine both increase sedation. Use Caution/Monitor.

• naratriptan

  Monitor Closely (1)naratriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• nefazodone

  Serious - Use Alternative (1)nefazodone and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• nettle

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

• nilotinib

  Minor (1)nilotinib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• norepinephrine

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

• nortriptyline

  Monitor Closely (2)brompheniramine 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 (2)nortriptyline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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 (3)brompheniramine 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.
  
  dextromethorphan, olanzapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• 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)brompheniramine 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)brompheniramine 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)brompheniramine and orphenadrine both increase sedation. Use Caution/Monitor.

• oxazepam

  Monitor Closely (2)brompheniramine 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)brompheniramine and oxycodone both increase sedation. Use Caution/Monitor.
  
  oxycodone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. 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.
  
  brompheniramine 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 (3)brompheniramine and paliperidone both increase sedation. Use Caution/Monitor.
  
  dextromethorphan, paliperidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  paliperidone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• panobinostat

  Monitor Closely (1)panobinostat will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Panobinostat can increase the levels and effects of sensitive CYP2D6 substrates or those with a narrow therapeutic index CYP2D6.

• papaveretum

  Monitor Closely (2)brompheniramine 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)brompheniramine and papaverine both increase sedation. Use Caution/Monitor.

• parecoxib

  Minor (1)parecoxib will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• paroxetine

  Serious - Use Alternative (2)paroxetine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  paroxetine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• passion flower

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

• pazopanib

  Monitor Closely (1)pazopanib increases levels of dextromethorphan by decreasing metabolism. Use Caution/Monitor.

• peginterferon alfa 2b

  Monitor Closely (1)peginterferon alfa 2b, dextromethorphan. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.

• pentazocine

  Monitor Closely (3)dextromethorphan and pentazocine both increase serotonin levels. Modify Therapy/Monitor Closely.
  
  pentazocine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and pentazocine both increase sedation. Use Caution/Monitor.

• pentobarbital

  Monitor Closely (2)brompheniramine 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.

• perampanel

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

• perphenazine

  Monitor Closely (4)perphenazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  dextromethorphan, perphenazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  brompheniramine and perphenazine both increase sedation. 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.Minor (1)perphenazine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• phendimetrazine

  Monitor Closely (3)brompheniramine 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 (2)phenelzine and dextromethorphan both increase serotonin levels. Contraindicated.
  
  phenelzine increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.Monitor Closely (1)phenelzine increases effects of brompheniramine 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)brompheniramine 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)brompheniramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  phentermine and phenylephrine both decrease sedation. 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)brompheniramine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• phenylephrine PO

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

• pholcodine

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

• pimavanserin

  Monitor Closely (1)dextromethorphan, pimavanserin. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• pimozide

  Monitor Closely (3)dextromethorphan, pimozide. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  brompheniramine 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)brompheniramine 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.

• pitolisant

  Serious - Use Alternative (1)brompheniramine decreases effects of pitolisant by Other (see comment). Avoid or Use Alternate Drug. Comment: Pitolisant increases histamine levels in the brain; therefore, H1 receptor antagonists that cross the blood-brain barrier may reduce the efficacy of pitolisant.

• prazosin

  Minor (1)prazosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.

• pregabalin

  Monitor Closely (1)pregabalin, brompheniramine. 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)brompheniramine and primidone both increase sedation. Use Caution/Monitor.
  
  primidone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• procarbazine

  Contraindicated (2)procarbazine increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.
  
  procarbazine and dextromethorphan both increase serotonin levels. Contraindicated. Combination is contraindicated within 2 weeks of MAOI use.

• prochlorperazine

  Monitor Closely (3)brompheniramine 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.
  
  brompheniramine 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.

• propafenone

  Minor (1)propafenone will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• propofol

  Monitor Closely (2)propofol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  propofol and brompheniramine 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.
  
  brompheniramine 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)protriptyline increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and protriptyline both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)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.
  
  protriptyline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• 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)brompheniramine 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 (3)quetiapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and quetiapine both increase sedation. Use Caution/Monitor.
  
  dextromethorphan, quetiapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• quinacrine

  Minor (1)quinacrine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• quinidine

  Monitor Closely (1)quinidine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• ramelteon

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

• ranolazine

  Minor (1)ranolazine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• rasagiline

  Contraindicated (1)rasagiline and dextromethorphan both increase serotonin levels. Contraindicated. Risk of psychosis episodes or bizarre behavior.Monitor Closely (1)rasagiline increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode.

• risperidone

  Monitor Closely (3)brompheniramine 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.
  
  dextromethorphan, risperidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• ritonavir

  Minor (1)ritonavir will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• rizatriptan

  Monitor Closely (1)rizatriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• rolapitant

  Monitor Closely (1)rolapitant will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor for adverse reactions when unable to avoid coadministration with narrow therapeutic index CYP2D6 substrates.

• safinamide

  Contraindicated (1)dextromethorphan, safinamide. Other (see comment). Contraindicated. Comment: Coadministration of MAOIs and dextromethorphan has been reported to cause episodes of psychosis or bizarre behavior.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.
  
  brompheniramine and sage both increase sedation. Minor/Significance Unknown.

• salmeterol

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

• SAMe

  Monitor Closely (1)dextromethorphan and SAMe both increase serotonin levels. Modify Therapy/Monitor Closely.

• scullcap

  Monitor Closely (2)brompheniramine 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.
  
  brompheniramine and secobarbital both increase sedation. Use Caution/Monitor.

• selegiline

  Contraindicated (1)selegiline and dextromethorphan both increase serotonin levels. Contraindicated.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.Serious - Use Alternative (1)selegiline transdermal and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.

• selinexor

  Serious - Use Alternative (1)selinexor, brompheniramine. unspecified interaction mechanism. Avoid or Use Alternate Drug. Patients treated with selinexor may experience neurological toxicities. Avoid taking selinexor with other medications that may cause dizziness or confusion.

• 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.

• sertraline

  Serious - Use Alternative (1)sertraline and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.Minor (1)sertraline will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• sevoflurane

  Monitor Closely (1)sevoflurane and brompheniramine 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)brompheniramine 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 brompheniramine 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)brompheniramine, 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.

• St John's Wort

  Serious - Use Alternative (1)dextromethorphan and St John's Wort both increase serotonin levels. Avoid or Use Alternate Drug.

• sufentanil

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

• sumatriptan

  Monitor Closely (1)sumatriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• sumatriptan intranasal

  Monitor Closely (1)sumatriptan intranasal and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• tapentadol

  Monitor Closely (2)brompheniramine 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.

• temazepam

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

• thioridazine

  Monitor Closely (3)brompheniramine 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.Minor (1)thioridazine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• thiothixene

  Monitor Closely (3)dextromethorphan, thiothixene. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  thiothixene increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and thiothixene both increase sedation. Use Caution/Monitor.

• timolol

  Monitor Closely (1)timolol increases effects of phenylephrine by pharmacodynamic synergism. Use Caution/Monitor. Risk of acute hypertensive episode (rare).

• tipranavir

  Minor (1)tipranavir will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.

• topiramate

  Monitor Closely (2)topiramate increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.
  
  brompheniramine and topiramate both increase sedation. Modify Therapy/Monitor Closely.

• tramadol

  Monitor Closely (3)brompheniramine 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.
  
  dextromethorphan and tramadol both increase serotonin levels. Modify Therapy/Monitor Closely.

• tranylcypromine

  Contraindicated (2)tranylcypromine and dextromethorphan both increase serotonin levels. Contraindicated.
  
  tranylcypromine increases effects of phenylephrine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.Serious - Use Alternative (1)tranylcypromine increases effects of brompheniramine 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)brompheniramine 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 (2)trazodone and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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)brompheniramine 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)brompheniramine 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 (4)dextromethorphan, trifluoperazine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).
  
  brompheniramine 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.
  
  brompheniramine and trimipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (2)trimipramine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  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)brompheniramine and triprolidine both increase sedation. Use Caution/Monitor.
  
  triprolidine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• valerian

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

• venlafaxine

  Serious - Use Alternative (2)venlafaxine and dextromethorphan both increase serotonin levels. Avoid or Use Alternate Drug.
  
  venlafaxine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• vilazodone

  Serious - Use Alternative (1)dextromethorphan, vilazodone. Either increases toxicity of the other by serotonin levels. Avoid or Use Alternate Drug. Concomitant therapy should be discontinued immediately if signs or symptoms of serotonin syndrome emerge and supportive symptomatic treatment should be initiated. .

• xylometazoline

  Monitor Closely (3)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.
  
  brompheniramine increases and xylometazoline decreases sedation. Effect of interaction is not clear, use caution. 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.
  
  brompheniramine increases and yohimbine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• ziconotide

  Monitor Closely (2)brompheniramine 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 (3)ziprasidone increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.
  
  brompheniramine and ziprasidone both increase sedation. Use Caution/Monitor.
  
  dextromethorphan, ziprasidone. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).

• zolmitriptan

  Monitor Closely (1)zolmitriptan and dextromethorphan both increase serotonin levels. Modify Therapy/Monitor Closely.

• zotepine

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