by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of propantheline by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.propofolpropofol and thioridazine both increase sedation. Use Caution/Monitor.propylhexedrinethioridazine increases and propylhexedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, propylhexedrine. 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.protriptylinethioridazine and protriptyline both increase sedation. Use Caution/Monitor.pseudoephedrinethioridazine, pseudoephedrine. Mechanism: unknown. Use Caution/Monitor. Consider avoiding use of pseudoephedrine in patients receiving phenothiazines (especially thioridazine) due to the potential risk of cardiac arrhythmia or sudden death. Monitor for evidence of ventricular arrhythmias during concomitant use.quazepamquazepam and thioridazine both increase sedation. Use Caution/Monitor.quetiapinequetiapine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.quetiapine and thioridazine both increase sedation. Use Caution/Monitor.quetiapine, thioridazine. Either increases toxicity of the other by QTc interval. Use Caution/Monitor. Avoid use with drugs that prolong QT and in patients with risk factors for prolonged QT interval. Postmarketing cases show QT prolongation with overdose in patients with concomitant illness or with drugs known to cause electrolyte imbalance or prolong QT.ramelteonthioridazine and ramelteon both increase sedation. Use Caution/Monitor.ranolazinethioridazine and ranolazine both increase QTc interval. Modify Therapy/Monitor Closely.rapacuroniumrapacuronium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.rapacuronium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of rapacuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.rilpivirinerilpivirine increases toxicity of thioridazine by QTc interval. Use Caution/Monitor. Rilpivirine should be used with caution when co-administered with a drug with a known risk of Torsade de Pointes.rimabotulinumtoxinBthioridazine, rimabotulinumtoxinB. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Anticholinergics may enhance botulinum toxin effects. Closely monitor for increased neuromuscular blockade.risperidonerisperidone and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.thioridazine and risperidone both increase QTc interval. Modify Therapy/Monitor Closely.risperidone and thioridazine both increase sedation. Use Caution/Monitor.ritlecitinibritlecitinib will increase the level or effect of thioridazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Ritlecitinib inhibits CYP3A4 substrates; coadministration increases AUC and peak plasma concentration sensitive substrates, which may increase risk of adverse reactions. Additional monitoring and dosage adjustment may be needed in accordance with product labeling of CYP3A substrates. rocuroniumrocuronium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.rocuronium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of rocuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.romidepsinthioridazine and romidepsin both increase QTc interval. Modify Therapy/Monitor Closely.ropeginterferon alfa 2bropeginterferon alfa 2b will increase the level or effect of thioridazine by Other (see comment). Use Caution/Monitor. Certain proinflammatory cytokines, including interferons, can suppress CYP450 enzymes resulting in increased exposures of some CYP substrates. Therefore, monitor patients who are receiving concomitant drugs that are CYP450 substrates with a narrow therapeutic index from toxicities to such drugs.salmeterolthioridazine increases and salmeterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.saquinavirsaquinavir, thioridazine. Either increases toxicity of the other by QTc interval. Modify Therapy/Monitor Closely. Use alternatives if available.scopolaminescopolamine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.scopolamine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of scopolamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.scullcapthioridazine and scullcap both increase sedation. Use Caution/Monitor.secobarbitalsecobarbital and thioridazine both increase sedation. Use Caution/Monitor.selpercatinibselpercatinib increases toxicity of thioridazine by QTc interval. Use Caution/Monitor.serdexmethylphenidate/dexmethylphenidatethioridazine, 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.sevofluranesevoflurane and thioridazine both increase sedation. Use Caution/Monitor.shepherd's pursethioridazine and shepherd's purse both increase sedation. Use Caution/Monitor.smokingsmoking decreases levels of thioridazine 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 toxicity of thioridazine by QTc interval. Use Caution/Monitor. Consider predose and post-colonoscopy ECGs in patients at increased risk of serious cardiac arrhythmias. .sodium sulfate/potassium sulfate/magnesium sulfatesodium sulfate/potassium sulfate/magnesium sulfate increases toxicity of thioridazine by QTc interval. Use Caution/Monitor. Consider predose and post-colonoscopy ECGs in patients at increased risk of serious cardiac arrhythmias. .solifenacinsolifenacin decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.solifenacin decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of solifenacin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.somapacitansomapacitan will decrease the level or effect of thioridazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Limited published data indicate that growth hormone treatment increases cytochrome P450 (CYP450)-mediated antipyrine clearance. Caution with sensitive CYP substratessomatrogonsomatrogon will decrease the level or effect of thioridazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Limited published data indicate that growth hormone treatment increases cytochrome P450 (CYP450)-mediated antipyrine clearance. Caution with sensitive CYP substratessomatropinsomatropin will decrease the level or effect of thioridazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Limited published data indicate that growth hormone treatment increases cytochrome P450 (CYP450)-mediated antipyrine clearance. Caution with sensitive CYP substratesstiripentolstiripentol, thioridazine. Either decreases toxicity 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.sufentanilsufentanil and thioridazine both increase sedation. Use Caution/Monitor.sulfamethoxazolethioridazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.tamsulosinthioridazine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.tapentadoltapentadol and thioridazine both increase sedation. Use Caution/Monitor.teclistamabteclistamab will increase the level or effect of thioridazine by altering metabolism. Use Caution/Monitor. Teclistamab causes release of cytokines that may suppress activity of CYP450 enzymes, resulting in increased exposure of CYP substrates. Monitor for increased concentrations or toxicities of sensitive CYP substrates. Adjust dose of CYP substrate drug as needed. teduglutideteduglutide increases levels of thioridazine by Other (see comment). Use Caution/Monitor. Comment: Teduglutide may increase absorption of concomitant PO medications; caution with with drugs requiring titration or those with a narrow therapeutic index; dose adjustment may be necessary.telavancinthioridazine and telavancin both increase QTc interval. Modify Therapy/Monitor Closely.temazepamtemazepam and thioridazine both increase sedation. Use Caution/Monitor.terbinafineterbinafine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.terbutalinethioridazine increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.tetrabenazinethioridazine and tetrabenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely.thiothixenethioridazine and thiothixene both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.thioridazine and thiothixene both increase sedation. Use Caution/Monitor.timololthioridazine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.tiotropiumtiotropium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.tiotropium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of tiotropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.tobacco usetobacco use decreases levels of thioridazine by increasing metabolism. Use Caution/Monitor. Interaction mainly seen w/chlorpromazine & thioridazine, but may occur w/other phenothiazines.tolterodinetolterodine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.tolterodine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.topiramatethioridazine and topiramate both increase sedation. Modify Therapy/Monitor Closely.tramadolthioridazine decreases effects of tramadol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Decreased conversion of tramadol to active metabolite.tramadol and thioridazine both increase sedation. Use Caution/Monitor.thioridazine decreases effects of tramadol by decreasing metabolism. Use Caution/Monitor. Decreased conversion of tramadol to active metabolite.trazodonethioridazine and trazodone both increase sedation. Use Caution/Monitor.triazolamtriazolam and thioridazine both increase sedation. Use Caution/Monitor.triclabendazoletriclabendazole and thioridazine both increase QTc interval. Use Caution/Monitor.triclofostriclofos and thioridazine both increase sedation. Use Caution/Monitor.trifluoperazinethioridazine and trifluoperazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.thioridazine and trifluoperazine both increase sedation. Use Caution/Monitor.trihexyphenidyltrihexyphenidyl decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.trimethoprimthioridazine and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.trimipraminethioridazine and trimipramine both increase sedation. Use Caution/Monitor.triprolidinetriprolidine and thioridazine both increase sedation. Use Caution/Monitor.trofinetidetrofinetide will increase the level or effect of thioridazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor CYP3A4 substrates for which a small increase in plasma concentration may lead to serious toxicities if coadministered with trofinetide (a weak CYP3A4 inhibitor).tropisetronthioridazine and tropisetron both increase QTc interval. Modify Therapy/Monitor Closely.trospium chloridetrospium chloride decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.trospium chloride decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of trospium chloride by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.ustekinumabustekinumab, thioridazine. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, normalizing the formation of CYP450 enzymes. Upon initiation or discontinuation of ustekinumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.vecuroniumvecuronium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.vecuronium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of vecuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.voclosporinvoclosporin, thioridazine. Either increases effects of the other by QTc interval. Use Caution/Monitor.voriconazolethioridazine and voriconazole both increase QTc interval. Modify Therapy/Monitor Closely.xylometazolinethioridazine increases and xylometazoline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, xylometazoline. 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.yohimbinethioridazine increases and yohimbine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, yohimbine. 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.ziconotidethioridazine and ziconotide both increase sedation. Use Caution/Monitor.ziprasidonethioridazine and ziprasidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.thioridazine and ziprasidone both increase sedation. Use Caution/Monitor.zolpidemthioridazine will increase the level or effect of zolpidem by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Additive effect of decreased alertness and psychomotor performancezotepinethioridazine and zotepine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.thioridazine and zotepine both increase sedation. Use Caution/Monitor.Minor (70)amantadineamantadine increases toxicity of thioridazine by pharmacodynamic synergism. Minor/Significance Unknown. May increase Parkinsonian tremor.amitriptylineamitriptyline, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.amitriptyline, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.amobarbitalthioridazine decreases levels of amobarbital by unspecified interaction mechanism. Minor/Significance Unknown.amoxapineamoxapine, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.amoxapine, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.aripiprazolethioridazine will increase the level or effect of aripiprazole by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.atropinethioridazine increases toxicity of atropine by unknown mechanism. Minor/Significance Unknown.atropine IV/IMthioridazine increases toxicity of atropine IV/IM by unknown mechanism. Minor/Significance Unknown.benazeprilthioridazine, benazepril. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. May increase risk of hypotension.brimonidinebrimonidine increases effects of thioridazine by pharmacodynamic synergism. Minor/Significance Unknown. Increased CNS depression.bupropionthioridazine increases toxicity of bupropion by unspecified interaction mechanism. Minor/Significance Unknown. May lower seizure threshold; keep bupropion dose as low as possible.butabarbitalthioridazine decreases levels of butabarbital by unspecified interaction mechanism. Minor/Significance Unknown.butalbitalthioridazine decreases levels of butalbital by unspecified interaction mechanism. Minor/Significance Unknown.captoprilthioridazine increases effects of captopril by unspecified interaction mechanism. Minor/Significance Unknown.chasteberrychasteberry decreases effects of thioridazine by pharmacodynamic antagonism. Minor/Significance Unknown. (Theoretical interaction).chloroquinechloroquine increases levels of thioridazine by decreasing metabolism. Minor/Significance Unknown.chlorpromazinethioridazine will increase the level or effect of chlorpromazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.clomipramineclomipramine, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.clomipramine, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.codeinethioridazine decreases effects of codeine by decreasing metabolism. Minor/Significance Unknown. Decreased conversion of codeine to active metabolite morphine.desipraminedesipramine, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.desipramine, thioridazine. Either increases levels of the other