Use Caution/Monitor.perphenazine increases effects of scopolamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.sarecyclinesarecycline will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Monitor for toxicities of P-gp substrates that may require dosage reduction when coadministered with P-gp inhibitors.scopolaminescopolamine and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.scullcapperphenazine and scullcap both increase sedation. Use Caution/Monitor.amitriptyline and scullcap both increase sedation. Use Caution/Monitor.secobarbitalsecobarbital will decrease the level or effect of amitriptyline by affecting hepatic enzyme CYP2C19 metabolism. Use Caution/Monitor.secobarbital and amitriptyline both increase sedation. Use Caution/Monitor.secobarbital and perphenazine both increase sedation. Use Caution/Monitor.selegilineselegiline, 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).selpercatinibselpercatinib increases toxicity of amitriptyline by QTc interval. Use Caution/Monitor.selpercatinibselpercatinib increases toxicity of perphenazine by QTc interval. Use Caution/Monitor.serdexmethylphenidate/dexmethylphenidateperphenazine, serdexmethylphenidate/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.sertralinesertraline and perphenazine both increase QTc interval. Use Caution/Monitor.sertraline and amitriptyline both increase QTc interval. Use Caution/Monitor.sevofluranesevoflurane and amitriptyline both increase sedation. Use Caution/Monitor.sevoflurane and perphenazine both increase sedation. Use Caution/Monitor.sevoflurane and amitriptyline both increase QTc interval. Use Caution/Monitor.sevoflurane and perphenazine both increase QTc interval. Use Caution/Monitor.shepherd's purseperphenazine and shepherd's purse both increase sedation. Use Caution/Monitor.amitriptyline and shepherd's purse both increase sedation. Use Caution/Monitor.simvastatinsimvastatin will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.siponimodsiponimod and perphenazine both increase QTc interval. Use Caution/Monitor.sirolimussirolimus will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.smokingsmoking decreases levels of perphenazine by increasing metabolism. Use Caution/Monitor. Interaction mainly seen w/chlorpromazine & thioridazine, but may occur w/other phenothiazines.sodium sulfate/?magnesium sulfate/potassium chloridesodium sulfate/?magnesium sulfate/potassium chloride increases effects of amitriptyline by unknown mechanism. Use Caution/Monitor. Closely monitor for evidence of seizures when using higher dose of magnesium sulfate together with drugs that lower the seizure threshold.sodium sulfate/?magnesium sulfate/potassium chloride increases effects of perphenazine by unknown mechanism. Use Caution/Monitor. Closely monitor for evidence of enhanced CNS depression when using higher dose of magnesium sulfate together with a CNS depressant.sodium sulfate/potassium chloride/magnesium sulfate/polyethylene glycolamitriptyline, sodium sulfate/potassium chloride/magnesium sulfate/polyethylene glycol. Other (see comment). Use Caution/Monitor. Comment: Caution when bowel preps are used with drugs that cause SIADH or NSAIDs; increased risk for water retention or electrolyte imbalance.sodium sulfate/potassium sulfate/magnesium sulfatesodium sulfate/potassium sulfate/magnesium sulfate increases effects of perphenazine by unknown mechanism. Use Caution/Monitor. Closely monitor for evidence of enhanced CNS depression when using higher dose of magnesium sulfate together with a CNS depressant.sodium sulfate/potassium sulfate/magnesium sulfatesodium sulfate/potassium sulfate/magnesium sulfate increases effects of amitriptyline by unknown mechanism. Use Caution/Monitor. Closely monitor for evidence of seizures when using higher dose of magnesium sulfate together with drugs that lower the seizure threshold.solifenacinsolifenacin and perphenazine both increase QTc interval. Use Caution/Monitor.solifenacin decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.solifenacin and amitriptyline both increase QTc interval. Use Caution/Monitor.solifenacin and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.solifenacin decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of solifenacin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.sorafenibsorafenib and amitriptyline both increase QTc interval. Use Caution/Monitor.sorafenib and perphenazine both increase QTc interval. Use Caution/Monitor.St John's WortSt John's Wort will decrease the level or effect of amitriptyline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.St John's Wort will decrease the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.stiripentolstiripentol, perphenazine. 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.stiripentolstiripentol, amitriptyline. 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.succinylcholinesuccinylcholine increases and amitriptyline decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.sufentanilsufentanil and amitriptyline both increase sedation. Use Caution/Monitor.sufentanil and perphenazine both increase sedation. Use Caution/Monitor.sufentanil SLsufentanil SL, amitriptyline. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Coadministration of drugs that affect the serotonergic neurotransmitter system may result in serotonin syndrome. If concomitant use is warranted, carefully observe the patient, particularly during treatment initiation and dose adjustment.sulfamethoxazoleperphenazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.sulfamethoxazoleamitriptyline and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.sumatriptansumatriptan, 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).sumatriptan and amitriptyline both increase serotonin levels. Modify Therapy/Monitor Closely.sumatriptan intranasalsumatriptan intranasal, 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).sumatriptan intranasal and amitriptyline both increase serotonin levels. Modify Therapy/Monitor Closely.sunitinibsunitinib and perphenazine both increase QTc interval. Use Caution/Monitor.suvorexantsuvorexant and amitriptyline both increase sedation. Modify Therapy/Monitor Closely. Dosage adjustments of suvorexant and concomitant CNS depressants may be necessarytacrolimustacrolimus and perphenazine both increase QTc interval. Use Caution/Monitor.tacrolimus will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.tamoxifenperphenazine decreases effects of tamoxifen by decreasing metabolism. Use Caution/Monitor. Inhibition of CYP2D6 metabolism to tamoxifen's active metabolite, endoxifen.tapentadoltapentadol and amitriptyline both increase sedation. Use Caution/Monitor.amitriptyline and tapentadol both increase serotonin levels. Modify Therapy/Monitor Closely.tapentadoltapentadol and perphenazine both increase sedation. Use Caution/Monitor.telavancinperphenazine and telavancin both increase QTc interval. Modify Therapy/Monitor Closely.amitriptyline and telavancin both increase QTc interval. Modify Therapy/Monitor Closely.temazepamtemazepam and amitriptyline both increase sedation. Use Caution/Monitor.temazepam and perphenazine both increase sedation. Use Caution/Monitor.terbinafineterbinafine will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.terbinafine will increase the level or effect of amitriptyline by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.terbutalineperphenazine increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amitriptyline increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.teriflunomideteriflunomide decreases levels of amitriptyline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.tetrabenazineperphenazine and tetrabenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely.tetrabenazinetetrabenazine and amitriptyline both increase QTc interval. Use Caution/Monitor.thioridazineperphenazine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.thioridazine and amitriptyline both increase sedation. Use Caution/Monitor.perphenazine and thioridazine both increase sedation. Use Caution/Monitor.thiothixeneperphenazine and thiothixene both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.perphenazine and thiothixene both increase sedation. Use Caution/Monitor.thiothixene and amitriptyline both increase sedation. Use Caution/Monitor.thyroid desiccatedthyroid desiccated increases effects of amitriptyline by Other (see comment). Use Caution/Monitor. Comment: Increased catecholamine receptor sensitivity; may increase CNS and cardiovascular effects, including arrhythmias.timololperphenazine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.tiotropiumtiotropium and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.tiotropium decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.tiotropium decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.perphenazine increases effects of tiotropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.tobacco usetobacco use decreases levels of perphenazine by increasing metabolism. Use Caution/Monitor. Interaction mainly seen w/chlorpromazine & thioridazine, but may occur w/other phenothiazines.tolterodinetolterodine and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.tolterodinetolterodine decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.tolterodine decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.tolvaptantolvaptan will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.topiramateamitriptyline and topiramate both increase sedation. Modify Therapy/Monitor Closely.perphenazine and topiramate both increase sedation. Modify Therapy/Monitor Closely.topiramate increases toxicity of amitriptyline by unspecified interaction mechanism. Use Caution/Monitor. Amitriptyline levels may increase; adjust dose based on clinical response and not on basis of plasma levels.tramadoltramadol and perphenazine both increase sedation. Use Caution/Monitor.amitriptyline and tramadol both increase serotonin levels. Modify Therapy/Monitor Closely.tramadol and amitriptyline both increase sedation. Use Caution/Monitor.tranylcyprominetranylcypromine, 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).trazodonetrazodone will decrease the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.amitriptyline and trazodone both decrease cholinergic effects/transmission. Use Caution/Monitor.amitriptyline and trazodone both increase sedation. Use Caution/Monitor.trazodoneperphenazine and trazodone both increase sedation. Use Caution/Monitor.triazolamtriazolam and perphenazine both increase sedation. Use Caution/Monitor.triazolam and amitriptyline both increase sedation. Use Caution/Monitor.triclofostriclofos and perphenazine both increase sedation. Use Caution/Monitor.triclofos and amitriptyline both increase sedation. Use Caution/Monitor.trifluoperazineperphenazine and trifluoperazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.perphenazine and trifluoperazine both increase sedation. Use Caution/Monitor.trifluoperazine and amitriptyline both increase sedation. Use Caution/Monitor.trihexyphenidyltrihexyphenidyl decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.trihexyphenidyl and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.perphenazine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.trimethoprimperphenazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.amitriptyline and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.trimipramineperphenazine and trimipramine both increase sedation. Use Caution/Monitor.amitriptyline and trimipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.amitriptyline and trimipramine both increase sedation. Use Caution/Monitor.triprolidinetriprolidine and perphenazine both increase sedation. Use Caution/Monitor.triprolidine and amitriptyline both increase sedation. Use Caution/Monitor.tropisetronperphenazine and tropisetron both increase QTc interval. Modify Therapy/Monitor Closely.amitriptyline and tropisetron both increase QTc interval. Modify Therapy/Monitor Closely.trospium chloridetrospium chloride decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.trospium chloride and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.perphenazine increases effects of trospium chloride by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.trospium chloride decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.tucatinibtucatinib will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Consider reducing the dosage of P-gp substrates, where minimal concentration changes may lead to serious or life-threatening toxicities.valbenazinevalbenazine and perphenazine both increase QTc interval. Use Caution/Monitor.valbenazinevalbenazine and amitriptyline both increase QTc interval. Use Caution/Monitor.valerianvalerian and amitriptyline both increase sedation. Use Caution/Monitor.vecuroniumvecuronium decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of vecuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.vecuronium decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.vecuronium and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.venlafaxinevenlafaxine, 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).amitriptyline and venlafaxine both increase QTc interval. Modify Therapy/Monitor Closely.venlafaxine will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.verapamilverapamil will increase the level or effect of amitriptyline by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. The frequency and severity of amitriptyline adverse effects (sedation, anticholinergic effects and orthostatic hypotension) may be increased. Cardiac dysrhythmic effects may be additive. vilazodonevilazodone, 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