Which drug will primary health care provider prescribe for a patient who has nighttime insomnia and motion sickness?

All Interactions Sort By: SeverityName

Contraindicated (1)

• eliglustat

  diphenhydramine increases levels of eliglustat by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. If coadministered with strong or moderate CYP2D6 inhibitors, reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive and intermediate metabolizers; eliglustat is contraindiated if strong or moderate CYP2D6 inhibitors are given concomitantly with strong or moderate CYP3A inhibitors.

Serious - Use Alternative (11)

• calcium/magnesium/potassium/sodium oxybates

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

• eluxadoline

  diphenhydramine, 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.

• isocarboxazid

  isocarboxazid increases effects of diphenhydramine 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. .

• mefloquine

  mefloquine increases toxicity of diphenhydramine by QTc interval. Avoid or Use Alternate Drug. Mefloquine may enhance the QTc prolonging effect of high risk QTc prolonging agents.

• metoclopramide intranasal

  diphenhydramine, 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.

• pitolisant

  diphenhydramine 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.

• pramlintide

  pramlintide, diphenhydramine. Either increases effects of the other by pharmacodynamic synergism. Contraindicated. Synergistic inhibition of GI motility.

• quinidine

  quinidine, diphenhydramine. Mechanism: pharmacodynamic synergism. Contraindicated. Risk of prolonged QTc interval.

• sodium oxybate

  diphenhydramine, 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.

• thioridazine

  diphenhydramine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

• tranylcypromine

  tranylcypromine increases effects of diphenhydramine 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. .

Monitor Closely (268)

• aclidinium

  diphenhydramine and aclidinium both decrease cholinergic effects/transmission. Use Caution/Monitor.

• albuterol

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

• alfentanil

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

• alprazolam

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

• amantadine

  diphenhydramine, amantadine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Potential for increased anticholinergic adverse effects.

• amifampridine

  diphenhydramine 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

  diphenhydramine and amitriptyline both decrease cholinergic effects/transmission. Modify Therapy/Monitor Closely.diphenhydramine and amitriptyline both increase sedation. Use Caution/Monitor.

• amobarbital

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

• amoxapine

  diphenhydramine and amoxapine both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and amoxapine both increase sedation. Use Caution/Monitor.

• anticholinergic/sedative combos

  anticholinergic/sedative combos and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• apomorphine

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

• arformoterol

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

• aripiprazole

  diphenhydramine and aripiprazole both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of aripiprazole by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of aripiprazole by pharmacodynamic antagonism. Use Caution/Monitor.aripiprazole increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• armodafinil

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

• atomoxetine

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

• atracurium

  atracurium and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• atropine

  atropine and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• atropine IV/IM

  atropine IV/IM and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• azelastine

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

• baclofen

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

• belladonna alkaloids

  belladonna alkaloids and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• belladonna and opium

  diphenhydramine and belladonna and opium both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and belladonna and opium both increase sedation. Use Caution/Monitor.

• benperidol

  diphenhydramine and benperidol both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of benperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of benperidol by pharmacodynamic antagonism. Use Caution/Monitor.benperidol increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• benzhydrocodone/acetaminophen

  diphenhydramine will increase the level or effect of benzhydrocodone/acetaminophen by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3%>

• benzphetamine

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

• benztropine

  benztropine and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor. Additive anticholinergic adverse effects may be seen with concurrent use.

• bethanechol

  bethanechol increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• brexanolone

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

• brexpiprazole

  diphenhydramine will increase the level or effect of brexpiprazole by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP2D6 inhibitor PLUS a strong/moderate CYP3A4 inhibitor.

• brompheniramine

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

• buprenorphine

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

• buprenorphine buccal

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

• butabarbital

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

• butalbital

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

• butorphanol

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

• caffeine

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

• carbachol

  carbachol increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• carbinoxamine

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

• carisoprodol

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

• carvedilol

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

• cenobamate

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

• cevimeline

  cevimeline increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• chloral hydrate

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

• chlordiazepoxide

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

• chlorpheniramine

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

• chlorpromazine

  diphenhydramine and chlorpromazine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of chlorpromazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of chlorpromazine by pharmacodynamic antagonism. Use Caution/Monitor.chlorpromazine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• chlorzoxazone

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

• cinnarizine

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

• cisatracurium

  cisatracurium and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• clemastine

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

• clobazam

  diphenhydramine, clobazam. Other (see comment). Use Caution/Monitor. Comment: Concomitant administration can increase the potential for CNS effects (e.g., increased sedation or respiratory depression).

• clomipramine

  diphenhydramine will increase the level or effect of clomipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and clomipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and clomipramine both increase sedation. Use Caution/Monitor.

• clonazepam

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

• clorazepate

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

• clozapine

  diphenhydramine and clozapine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of clozapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of clozapine by pharmacodynamic antagonism. Use Caution/Monitor.clozapine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• codeine

  diphenhydramine decreases effects of codeine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Prevents conversion of codeine to its active metabolite morphine.diphenhydramine and codeine both increase sedation. Use Caution/Monitor.

• cyclizine

  cyclizine and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.cyclizine and diphenhydramine both increase sedation. Use Caution/Monitor.

• cyclobenzaprine

  cyclobenzaprine and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and cyclobenzaprine both increase sedation. Use Caution/Monitor.

• cyproheptadine

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

• dantrolene

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

• daridorexant

  diphenhydramine 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

  darifenacin and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• desflurane

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

• desipramine

  diphenhydramine will increase the level or effect of desipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and desipramine both increase sedation. Use Caution/Monitor.

• deutetrabenazine

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

• dexchlorpheniramine

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

• dexfenfluramine

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

• dexmedetomidine

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

• dexmethylphenidate

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

• dextroamphetamine

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

• dextromoramide

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

• diamorphine

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

• diazepam

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

• diazepam intranasal

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

• dicyclomine

  dicyclomine and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• diethylpropion

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

• difelikefalin

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

• difenoxin hcl

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

• dimenhydrinate

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

• diphenoxylate hcl

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

• dipipanone

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

• dobutamine

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

• donepezil

  donepezil increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• donepezil transdermal

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

• dopamine

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

• dopexamine

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

• dosulepin

  diphenhydramine and dosulepin both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and dosulepin both increase sedation. Use Caution/Monitor.

• doxepin

  diphenhydramine and doxepin both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and doxepin both increase sedation. Use Caution/Monitor.

• doxylamine

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

• droperidol

  diphenhydramine and droperidol both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of droperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of droperidol by pharmacodynamic antagonism. Use Caution/Monitor.droperidol increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• duloxetine

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

• echothiophate iodide

  echothiophate iodide increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• ephedrine

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

• epinephrine

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

• epinephrine racemic

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

• esketamine intranasal

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

• estazolam

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

• ethanol

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

• etomidate

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

• fenfluramine

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

• fentanyl

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

• fentanyl intranasal

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

• fentanyl transdermal

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

• fentanyl transmucosal

  fentanyl transmucosal, diphenhydramine. 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.

• fesoterodine

  diphenhydramine and fesoterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• flavoxate

  diphenhydramine and flavoxate both decrease cholinergic effects/transmission. Use Caution/Monitor.

• flecainide

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

• flibanserin

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

• fluphenazine

  diphenhydramine and fluphenazine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of fluphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of fluphenazine by pharmacodynamic antagonism. Use Caution/Monitor.fluphenazine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• flurazepam

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

• formoterol

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

• gabapentin

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

• gabapentin enacarbil

  gabapentin enacarbil, diphenhydramine. 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.

• galantamine

  galantamine increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• ganaxolone

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

• glycopyrrolate

  diphenhydramine and glycopyrrolate both decrease cholinergic effects/transmission. Use Caution/Monitor.

• glycopyrrolate inhaled

  diphenhydramine and glycopyrrolate inhaled both decrease cholinergic effects/transmission. Use Caution/Monitor.

• glycopyrronium tosylate topical

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

• haloperidol

  diphenhydramine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and haloperidol both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.haloperidol increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• hawthorn

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

• henbane

  diphenhydramine and henbane both decrease cholinergic effects/transmission. Use Caution/Monitor.

• homatropine

  diphenhydramine and homatropine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• hops

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

• huperzine A

  huperzine A increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• hyaluronidase

  diphenhydramine 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.

• hydrocodone

  diphenhydramine will increase the level or effect of hydrocodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3%>

• hydromorphone

  diphenhydramine will increase the level or effect of hydromorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and hydromorphone both increase sedation. Use Caution/Monitor.

• hydroxyzine

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

• hyoscyamine

  diphenhydramine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• hyoscyamine spray

  diphenhydramine and hyoscyamine spray both decrease cholinergic effects/transmission. Use Caution/Monitor.

• iloperidone

  diphenhydramine will increase the level or effect of iloperidone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and iloperidone both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of iloperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of iloperidone by pharmacodynamic antagonism. Use Caution/Monitor.iloperidone increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• imipramine

  diphenhydramine will increase the level or effect of imipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and imipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and imipramine both increase sedation. Use Caution/Monitor.

• ipratropium

  diphenhydramine and ipratropium both decrease cholinergic effects/transmission. Use Caution/Monitor. Due to the poor systemic absorption of ipratropium, interaction unlikely at regularly recommended dosages.

• isoproterenol

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

• kava

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

• ketamine

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

• ketotifen, ophthalmic

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

• lasmiditan

  lasmiditan, diphenhydramine. Either increases effects of the other by sedation. Use Caution/Monitor. Coadministration of lasmiditan and other CNS depressant drugs, including alcohol have not been evaluated in clinical studies. Lasmiditan may cause sedation, as well as other cognitive and/or neuropsychiatric adverse reactions.

• lemborexant

  lemborexant, diphenhydramine. 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

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

• levodopa

  diphenhydramine, levodopa. Other (see comment). Use Caution/Monitor. Comment: Anticholinergic agents may enhance the therapeutic effects of levodopa; however, anticholinergic agents can exacerbate tardive dyskinesia. In high dosage, anticholinergics may decrease the effects of levodopa by delaying its GI absorption. .

• levorphanol

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

• lisdexamfetamine

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

• lofepramine

  diphenhydramine will increase the level or effect of lofepramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and lofepramine both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and lofepramine both increase sedation. Use Caution/Monitor.

• lofexidine

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

• loprazolam

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

• lorazepam

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

• lormetazepam

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

• loxapine

  diphenhydramine and loxapine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of loxapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of loxapine by pharmacodynamic antagonism. Use Caution/Monitor.loxapine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• loxapine inhaled

  loxapine inhaled increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.diphenhydramine and loxapine inhaled both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of loxapine inhaled by pharmacodynamic antagonism. Use Caution/Monitor.

• lurasidone

  lurasidone, diphenhydramine. 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

  diphenhydramine and maprotiline both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and maprotiline both increase sedation. Use Caution/Monitor.

• marijuana

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

• meclizine

  diphenhydramine and meclizine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• melatonin

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

• meperidine

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

• meprobamate

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

• metaproterenol

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

• metaxalone

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

• methadone

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

• methamphetamine

  diphenhydramine will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• methocarbamol

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

• methscopolamine

  diphenhydramine and methscopolamine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• methylenedioxymethamphetamine

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

• metoprolol

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

• mexiletine

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

• midazolam

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

• midazolam intranasal

  midazolam intranasal, diphenhydramine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.

• midodrine

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

• mirtazapine

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

• modafinil

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

• morphine

  diphenhydramine will increase the level or effect of morphine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and morphine both increase sedation. Use Caution/Monitor.

• motherwort

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

• moxonidine

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

• nabilone

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

• nalbuphine

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

• nebivolol

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

• neostigmine

  neostigmine increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• norepinephrine

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

• nortriptyline

  diphenhydramine will increase the level or effect of nortriptyline by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and nortriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and nortriptyline both increase sedation. Use Caution/Monitor.

• olanzapine

  diphenhydramine and olanzapine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of olanzapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of olanzapine by pharmacodynamic antagonism. Use Caution/Monitor.olanzapine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• oliceridine

  diphenhydramine will increase the level or effect of oliceridine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.

• onabotulinumtoxinA

  onabotulinumtoxinA and diphenhydramine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• opium tincture

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

• orphenadrine

  diphenhydramine and orphenadrine both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and orphenadrine both increase sedation. Use Caution/Monitor.

• ospemifene

  diphenhydramine, ospemifene. Either increases levels of the other by plasma protein binding competition. Modify Therapy/Monitor Closely.

• oxazepam

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

• oxybutynin

  diphenhydramine and oxybutynin both decrease cholinergic effects/transmission. Use Caution/Monitor.

• oxybutynin topical

  diphenhydramine and oxybutynin topical both decrease cholinergic effects/transmission. Use Caution/Monitor.

• oxybutynin transdermal

  diphenhydramine and oxybutynin transdermal both decrease cholinergic effects/transmission. Use Caution/Monitor.

• oxycodone

  diphenhydramine will increase the level or effect of oxycodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and oxycodone both increase sedation. Use Caution/Monitor.

• oxymorphone

  diphenhydramine will increase the level or effect of oxymorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.diphenhydramine and oxymorphone both increase sedation. Use Caution/Monitor.

• paliperidone

  diphenhydramine and paliperidone both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of paliperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of paliperidone by pharmacodynamic antagonism. Use Caution/Monitor.paliperidone increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• pancuronium

  diphenhydramine and pancuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.

• papaveretum

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

• papaverine

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

• passion flower

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

• pentazocine

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

• pentobarbital

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

• perampanel

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

• perphenazine

  diphenhydramine and perphenazine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• phendimetrazine

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

• phenelzine

  phenelzine increases effects of diphenhydramine 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

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

• phentermine

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

• phenylephrine

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

• phenylephrine PO

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

• pholcodine

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

• physostigmine

  physostigmine increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• pilocarpine

  pilocarpine increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• pimozide

  diphenhydramine and pimozide both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of pimozide by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of pimozide by pharmacodynamic antagonism. Use Caution/Monitor.pimozide increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• pirbuterol

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

• pralidoxime

  diphenhydramine and pralidoxime both decrease cholinergic effects/transmission. Use Caution/Monitor.

• pregabalin

  pregabalin, diphenhydramine. 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

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

• prochlorperazine

  diphenhydramine and prochlorperazine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of prochlorperazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of prochlorperazine by pharmacodynamic antagonism. Use Caution/Monitor.prochlorperazine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• promethazine

  diphenhydramine and promethazine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of promethazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of promethazine by pharmacodynamic antagonism. Use Caution/Monitor.promethazine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• propafenone

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

• propantheline

  diphenhydramine and propantheline both decrease cholinergic effects/transmission. Use Caution/Monitor.

• propofol

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

• propranolol

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

• propylhexedrine

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

• protriptyline

  diphenhydramine and protriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and protriptyline both increase sedation. Use Caution/Monitor.

• pyridostigmine

  pyridostigmine increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• quazepam

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

• quetiapine

  diphenhydramine and quetiapine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of quetiapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of quetiapine by pharmacodynamic antagonism. Use Caution/Monitor.quetiapine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• ramelteon

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

• rapacuronium

  diphenhydramine and rapacuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.

• risperidone

  diphenhydramine and risperidone both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of risperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of risperidone by pharmacodynamic antagonism. Use Caution/Monitor.risperidone increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• rocuronium

  diphenhydramine and rocuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.

• salmeterol

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

• scopolamine

  diphenhydramine and scopolamine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• scullcap

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

• secobarbital

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

• sevoflurane

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

• shepherd's purse

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

• solifenacin

  diphenhydramine and solifenacin both decrease cholinergic effects/transmission. Use Caution/Monitor.

• stiripentol

  stiripentol, diphenhydramine. Either increases effects of the other by sedation. Use Caution/Monitor. Concomitant use stiripentol with other CNS depressants, including alcohol, may increase the risk of sedation and somnolence.

• succinylcholine

  succinylcholine increases and diphenhydramine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

• sufentanil

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

• tamoxifen

  diphenhydramine decreases effects of tamoxifen by decreasing metabolism. Use Caution/Monitor. Inhibition of CYP2D6 metabolism to tamoxifen's active metabolite, endoxifen.

• tamsulosin

  diphenhydramine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

• tapentadol

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

• temazepam

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

• terbutaline

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

• thioridazine

  diphenhydramine and thioridazine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• thiothixene

  diphenhydramine and thiothixene both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of thiothixene by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of thiothixene by pharmacodynamic antagonism. Use Caution/Monitor.thiothixene increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• timolol

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

• tiotropium

  diphenhydramine and tiotropium both decrease cholinergic effects/transmission. Use Caution/Monitor.

• tolterodine

  diphenhydramine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.

• topiramate

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

• tramadol

  diphenhydramine decreases effects of tramadol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Decreased conversion of tramadol to active metabolite.diphenhydramine and tramadol both increase sedation. Use Caution/Monitor.diphenhydramine decreases effects of tramadol by decreasing metabolism. Use Caution/Monitor. Decreased conversion of tramadol to active metabolite.

• trazodone

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

• triazolam

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

• triclofos

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

• trifluoperazine

  diphenhydramine and trifluoperazine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of trifluoperazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of trifluoperazine by pharmacodynamic antagonism. Use Caution/Monitor.trifluoperazine increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• trihexyphenidyl

  diphenhydramine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

• trimipramine

  diphenhydramine and trimipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.diphenhydramine and trimipramine both increase sedation. Use Caution/Monitor.

• triprolidine

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

• trospium chloride

  diphenhydramine and trospium chloride both decrease cholinergic effects/transmission. Use Caution/Monitor.

• valerian

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

• vecuronium

  diphenhydramine and vecuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.

• xylometazoline

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

• yohimbine

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

• ziconotide

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

• ziprasidone

  diphenhydramine and ziprasidone both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of ziprasidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of ziprasidone by pharmacodynamic antagonism. Use Caution/Monitor.ziprasidone increases effects of diphenhydramine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

• zotepine

  diphenhydramine and zotepine both increase sedation. Use Caution/Monitor.diphenhydramine decreases levels of zotepine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.diphenhydramine decreases levels of zotepine by pharmacodynamic antagonism. Use Caution/Monitor.

Minor (34)

• aripiprazole

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

• ashwagandha

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

• brimonidine

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

• chlorpromazine

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

• desipramine

  diphenhydramine and desipramine both decrease cholinergic effects/transmission. Minor/Significance Unknown.desipramine and diphenhydramine both decrease cholinergic effects/transmission. Minor/Significance Unknown.

• dexfenfluramine

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

• dextroamphetamine

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

• dextromethorphan

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

• dimenhydrinate

  dimenhydrinate increases toxicity of diphenhydramine by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.

• donepezil

  diphenhydramine will increase the level or effect of donepezil by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.donepezil decreases effects of diphenhydramine by pharmacodynamic antagonism. Minor/Significance Unknown.

• doxepin

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

• encainide

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

• eucalyptus

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

• fesoterodine

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

• fluoxetine

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

• fluphenazine

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

• galantamine

  diphenhydramine will increase the level or effect of galantamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.galantamine decreases effects of diphenhydramine by pharmacodynamic antagonism. Minor/Significance Unknown.

• loratadine

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

• nettle

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

• nitazoxanide

  nitazoxanide, diphenhydramine. Either increases levels of the other by Mechanism: plasma protein binding competition. Minor/Significance Unknown.

• oxycodone

  diphenhydramine decreases effects of oxycodone by decreasing metabolism. Minor/Significance Unknown. Decreased conversion of oxycodone to active metabolite morphine.

• paroxetine

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

• perhexiline

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

• perphenazine

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

• prochlorperazine

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

• promazine

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

• promethazine

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

• risperidone

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

• sage

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

• Siberian ginseng

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

• tolterodine

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

• trazodone

  diphenhydramine and trazodone both decrease cholinergic effects/transmission. Minor/Significance Unknown.

• trifluoperazine

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

• tropisetron

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

• aclidinium

  Monitor Closely (1)diphenhydramine and aclidinium both decrease cholinergic effects/transmission. Use Caution/Monitor.

• albuterol

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

• alfentanil

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

• alprazolam

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

• amantadine

  Monitor Closely (1)diphenhydramine, amantadine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Potential for increased anticholinergic adverse effects.

• amifampridine

  Monitor Closely (1)diphenhydramine 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

  Monitor Closely (2)diphenhydramine and amitriptyline both decrease cholinergic effects/transmission. Modify Therapy/Monitor Closely.

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