levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of cyclobenzaprine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.cyproheptadinecyproheptadine and perphenazine both increase sedation. Use Caution/Monitor.dantrolenedantrolene and perphenazine both increase sedation. Use Caution/Monitor.daridorexantperphenazine 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. darifenacindarifenacin decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.darifenacin decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of darifenacin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.dasatinibperphenazine and dasatinib both increase QTc interval. Modify Therapy/Monitor Closely.desfluranedesflurane and perphenazine both increase sedation. Use Caution/Monitor.desflurane and perphenazine both increase QTc interval. Use Caution/Monitor.desipramineperphenazine will increase the level or effect of desipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.perphenazine and desipramine both increase sedation. Use Caution/Monitor.desvenlafaxinedesvenlafaxine will increase the level or effect of perphenazine 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 mgdeutetrabenazineperphenazine and deutetrabenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely. The risk for parkinsonism, neuroleptic malignant syndrome, and akathisia may be increased by concomitant use of deutetrabenazine and dopamine antagonists or antipsychotics.perphenazine and deutetrabenazine both increase sedation. Use Caution/Monitor.deutetrabenazine and perphenazine both increase QTc interval. Use Caution/Monitor. At the maximum recommended dose, deutetrabenazine does not prolong QT interval to a clinically relevant extent. Certain circumstances may increase risk of torsade de pointes and/or sudden death in association with drugs that prolong the QTc interval (eg, bradycardia, hypokalemia or hypomagnesemia, coadministration with other drugs that prolong QTc interval, presence of congenital QT prolongation).dexchlorpheniraminedexchlorpheniramine and perphenazine both increase sedation. Use Caution/Monitor.dexfenfluramineperphenazine increases and dexfenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, dexfenfluramine. 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.dexmedetomidinedexmedetomidine and perphenazine both increase sedation. Use Caution/Monitor.dexmethylphenidateperphenazine increases and dexmethylphenidate decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, dexmethylphenidate. 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.dextroamphetamineperphenazine increases and dextroamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, dextroamphetamine. 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.dextroamphetamine transdermalperphenazine, 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).dextromethorphandextromethorphan, 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).dextromoramidedextromoramide and perphenazine both increase sedation. Use Caution/Monitor.diamorphinediamorphine and perphenazine both increase sedation. Use Caution/Monitor.diazepamdiazepam and perphenazine both increase sedation. Use Caution/Monitor.dicyclominedicyclomine decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.dicyclomine decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of dicyclomine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.diethylpropionperphenazine increases and diethylpropion decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, diethylpropion. 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.difelikefalindifelikefalin and perphenazine both increase sedation. Use Caution/Monitor.difenoxin hcldifenoxin hcl and perphenazine both increase sedation. Use Caution/Monitor.dihydroergotaminedihydroergotamine, 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).dimenhydrinatedimenhydrinate and perphenazine both increase sedation. Use Caution/Monitor.diphenhydraminediphenhydramine 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.diphenoxylate hcldiphenoxylate hcl and perphenazine both increase sedation. Use Caution/Monitor.dipipanonedipipanone and perphenazine both increase sedation. Use Caution/Monitor.dobutamineperphenazine increases and dobutamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, dobutamine. 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.dofetilidedofetilide increases toxicity of perphenazine by QTc interval. Use Caution/Monitor.dolasetronperphenazine and dolasetron both increase QTc interval. Modify Therapy/Monitor Closely.donepezildonepezil and perphenazine both increase QTc interval. Use Caution/Monitor.donepezil transdermaldonepezil transdermal, perphenazine. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.dopamineperphenazine increases and dopamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, dopamine. 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.dopexamineperphenazine increases and dopexamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dosulepinperphenazine and dosulepin both increase sedation. Use Caution/Monitor.doxepinperphenazine and doxepin both increase sedation. Use Caution/Monitor.doxylaminedoxylamine and perphenazine both increase sedation. Use Caution/Monitor.droperidoldroperidol and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.droperidol and perphenazine both increase sedation. Use Caution/Monitor.duloxetineperphenazine will increase the level or effect of duloxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.efavirenzefavirenz and perphenazine both increase QTc interval. Use Caution/Monitor.eletriptaneletriptan, 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).eliglustateliglustat increases levels of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the concomitant drug and titrate to clinical effect.eliglustat and perphenazine both increase QTc interval. Use Caution/Monitor.elvitegravir/cobicistat/emtricitabine/tenofovir DFelvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP2D6 inhibitor; A decrease in dose of the neuroleptic may be needed when coadministered.encorafenibencorafenib and perphenazine both increase QTc interval. Use Caution/Monitor.entrectinibentrectinib and perphenazine both increase QTc interval. Use Caution/Monitor.ephedrineperphenazine increases and ephedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, ephedrine. 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.epinephrineperphenazine increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, epinephrine. 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 decreases effects of epinephrine by pharmacodynamic antagonism. Use Caution/Monitor. Block pressor response to epinephrine, which may result in severe hypotension and tachycardia.epinephrine racemicperphenazine increases and epinephrine racemic decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine decreases effects of epinephrine racemic by pharmacodynamic antagonism. Use Caution/Monitor. Block pressor response to epinephrine, which may result in severe hypotension and tachycardia.ergoloid mesylatesergoloid mesylates, 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).ergotamineergotamine, 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).eribulineribulin and perphenazine both increase QTc interval. Use Caution/Monitor.escitalopramescitalopram increases toxicity of perphenazine by QTc interval. Use Caution/Monitor.estazolamestazolam and perphenazine both increase sedation. Use Caution/Monitor.ethanolperphenazine and ethanol both increase sedation. Use Caution/Monitor.etomidateetomidate and perphenazine both increase sedation. Use Caution/Monitor.fedratinibfedratinib will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.fenfluramineperphenazine increases and fenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, fenfluramine. 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.fentanylfentanyl, 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).fesoterodinefesoterodine decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.fingolimodfingolimod and perphenazine both increase QTc interval. Use Caution/Monitor.flavoxateflavoxate decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.flavoxate decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of flavoxate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.flecainideperphenazine will increase the level or effect of flecainide by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.perphenazine and flecainide both increase QTc interval. Modify Therapy/Monitor Closely.flibanserinflibanserin, perphenazine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. 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).fluphenazinefluphenazine and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.fluphenazine and perphenazine both increase sedation. Use Caution/Monitor.flurazepamflurazepam and perphenazine both increase sedation. Use Caution/Monitor.fluvoxaminefluvoxamine and perphenazine both increase QTc interval. Use Caution/Monitor.formoterolperphenazine increases and formoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.foscarnetperphenazine and foscarnet both increase QTc interval. Modify Therapy/Monitor Closely.frovatriptanfrovatriptan, 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).ganaxoloneperphenazine and ganaxolone both increase sedation. Use Caution/Monitor.gemifloxacingemifloxacin and perphenazine both increase QTc interval. Use Caution/Monitor.gilteritinibgilteritinib and perphenazine both increase QTc interval. Use Caution/Monitor.glycopyrrolateperphenazine increases toxicity of glycopyrrolate by unknown mechanism. Use Caution/Monitor.perphenazine increases effects of glycopyrrolate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.glycopyrrolate inhaledglycopyrrolate inhaled decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.glycopyrrolate inhaled decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of glycopyrrolate inhaled by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.perphenazine increases toxicity of glycopyrrolate inhaled by unknown mechanism. Use Caution/Monitor.glycopyrronium tosylate topicalglycopyrronium tosylate topical, perphenazine. 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.granisetrongranisetron and perphenazine both increase QTc interval. Use Caution/Monitor.guanfacineguanfacine, perphenazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.haloperidolperphenazine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.haloperidol and perphenazine both increase