Additive anticholinergic effects.desvenlafaxineMonitor Closely (1)desvenlafaxine will increase the level or effect of thioridazine 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 mgdeutetrabenazineMonitor Closely (3)thioridazine and deutetrabenazine 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). thioridazine 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. thioridazine will increase the level or effect of deutetrabenazine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Strong CYP2D6 inhibitors increase the systemic exposure to the active dihydro-metabolites of deutetrabenazine by approximately 3-fold. Do not exceed 18 mg/dose and 36 mg/day of deutetrabenazine if coadministered with strong CYP2D6 inhibitors.dexchlorpheniramineMonitor Closely (1)dexchlorpheniramine and thioridazine both increase sedation. Use Caution/Monitor.dexfenfluramineMonitor Closely (2)thioridazine, 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. thioridazine increases and dexfenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)thioridazine will increase the level or effect of dexfenfluramine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.dexmedetomidineMonitor Closely (1)dexmedetomidine and thioridazine both increase sedation. Use Caution/Monitor.dexmethylphenidateMonitor Closely (2)thioridazine, 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. thioridazine increases and dexmethylphenidate decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dextroamphetamineMonitor Closely (2)thioridazine, 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. thioridazine increases and dextroamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)thioridazine will increase the level or effect of dextroamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.dextroamphetamine transdermalMonitor Closely (1)thioridazine will increase the level or effect of dextroamphetamine transdermal by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Initiate with lower doses and monitor patients for signs and symptoms of serotonin syndrome, particularly during dextroamphetamine initiation and after a dosage increase. If serotonin syndrome occurs, discontinue dextroamphetamine transdermal and CYP2D6 inhibitor.dextromethorphanMinor (1)thioridazine will increase the level or effect of dextromethorphan by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.dextromoramideMonitor Closely (1)dextromoramide and thioridazine both increase sedation. Use Caution/Monitor.diamorphineMonitor Closely (1)diamorphine and thioridazine both increase sedation. Use Caution/Monitor.diazepamMonitor Closely (1)diazepam and thioridazine both increase sedation. Use Caution/Monitor.dicyclomineMonitor Closely (3)dicyclomine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. dicyclomine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor. thioridazine increases effects of dicyclomine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.diethylpropionMonitor Closely (2)thioridazine, 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. thioridazine increases and diethylpropion decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.difelikefalinMonitor Closely (1)difelikefalin and thioridazine both increase sedation. Use Caution/Monitor.difenoxin hclMonitor Closely (1)difenoxin hcl and thioridazine both increase sedation. Use Caution/Monitor.dimenhydrinateMonitor Closely (1)dimenhydrinate and thioridazine both increase sedation. Use Caution/Monitor.diphenhydramineMonitor Closely (4)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. diphenhydramine and thioridazine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)diphenhydramine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.diphenoxylate hclMonitor Closely (1)diphenoxylate hcl and thioridazine both increase sedation. Use Caution/Monitor.dipipanoneMonitor Closely (1)dipipanone and thioridazine both increase sedation. Use Caution/Monitor.disopyramideContraindicated (1)thioridazine and disopyramide both increase QTc interval. Contraindicated.dobutamineMonitor Closely (2)thioridazine, 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. thioridazine increases and dobutamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dofetilideContraindicated (1)dofetilide increases toxicity of thioridazine by QTc interval. Contraindicated.Serious - Use Alternative (1)thioridazine and dofetilide both increase QTc interval. Avoid or Use Alternate Drug.dolasetronMonitor Closely (1)thioridazine and dolasetron both increase QTc interval. Modify Therapy/Monitor Closely.donepezilContraindicated (1)donepezil and thioridazine both increase QTc interval. Contraindicated.Minor (1)thioridazine will increase the level or effect of donepezil by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.donepezil transdermalMonitor Closely (1)donepezil transdermal, thioridazine. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.dopamineMonitor Closely (2)thioridazine, 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. thioridazine increases and dopamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)thioridazine decreases effects of dopamine by pharmacodynamic antagonism. Contraindicated.dopexamineMonitor Closely (1)thioridazine increases and dopexamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dosulepinMonitor Closely (1)thioridazine and dosulepin both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)thioridazine and dosulepin both increase QTc interval. Avoid or Use Alternate Drug.doxepinContraindicated (1)thioridazine will increase the level or effect of doxepin by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.Monitor Closely (1)thioridazine and doxepin both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)thioridazine and doxepin both increase QTc interval. Avoid or Use Alternate Drug.Minor (2)doxepin, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects. doxepin, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.doxylamineMonitor Closely (1)doxylamine and thioridazine both increase sedation. Use Caution/Monitor.dronedaroneSerious - Use Alternative (2)thioridazine and dronedarone both increase QTc interval. Avoid or Use Alternate Drug. dronedarone will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.droperidolMonitor Closely (2)droperidol and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. droperidol and thioridazine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)thioridazine and droperidol both increase QTc interval. Avoid or Use Alternate Drug.duloxetineSerious - Use Alternative (2)duloxetine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. thioridazine will increase the level or effect of duloxetine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.eliglustatContraindicated (2)thioridazine 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. eliglustat and thioridazine both increase QTc interval. Contraindicated.Monitor Closely (1)eliglustat increases levels of thioridazine 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.elvitegravir/cobicistat/emtricitabine/tenofovir DFMonitor Closely (1)elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of thioridazine 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.enalaprilMinor (1)thioridazine increases effects of enalapril by unspecified interaction mechanism. Minor/Significance Unknown.encainideMinor (1)thioridazine will increase the level or effect of encainide by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.encorafenibSerious - Use Alternative (1)encorafenib and thioridazine both increase QTc interval. Avoid or Use Alternate Drug. Encorafenib is associated with dose-dependent QTc interval prolongation. Avoid with drugs known to prolong QT interval.entrectinibSerious - Use Alternative (1)thioridazine and entrectinib both increase QTc interval. Avoid or Use Alternate Drug.epcoritamabMonitor Closely (1)epcoritamab, thioridazine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Epcoritamab causes release of cytokines that may suppress activity of CYP enzymes, resulting in increased exposure of CYP substrates. For certain CYP substrates, minimal changes in their concentration may lead to serious adverse reactions. If needed, modify therapy as recommended in the substrate's prescribing information. .ephedrineMonitor Closely (2)thioridazine, 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. thioridazine increases and ephedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.epinephrineMonitor Closely (3)thioridazine, 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. thioridazine decreases effects of epinephrine by pharmacodynamic antagonism. Use Caution/Monitor. Block pressor response to epinephrine, which may result in severe hypotension and tachycardia. thioridazine increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)epinephrine and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.epinephrine racemicMonitor Closely (2)thioridazine decreases effects of epinephrine racemic by pharmacodynamic antagonism. Use Caution/Monitor. Block pressor response to epinephrine, which may result in severe hypotension and tachycardia. thioridazine increases and epinephrine racemic decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)epinephrine racemic and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.eribulinSerious - Use Alternative (1)eribulin and thioridazine both increase QTc interval. Avoid or Use Alternate Drug. Potential for enhanced QTc-prolonging effects; if concurrent use is necessary then ECG monitoring is recommended.erythromycin baseSerious - Use Alternative (1)thioridazine and erythromycin base both increase QTc interval. Avoid or Use Alternate Drug.erythromycin ethylsuccinateSerious - Use Alternative (1)thioridazine and erythromycin ethylsuccinate both increase QTc interval. Avoid or Use Alternate Drug.erythromycin lactobionateSerious - Use Alternative (1)thioridazine and erythromycin lactobionate both increase QTc interval. Avoid or Use Alternate Drug.erythromycin stearateSerious - Use Alternative (1)thioridazine and erythromycin stearate both increase QTc interval. Avoid or Use Alternate Drug.escitalopramContraindicated (1)escitalopram increases toxicity of thioridazine by QTc interval. Contraindicated.esketamine intranasalMonitor Closely (1)esketamine intranasal, thioridazine. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely.estazolamMonitor Closely (1)estazolam and thioridazine both increase sedation. Use Caution/Monitor.ethanolMonitor Closely (1)thioridazine and ethanol both increase sedation. Use Caution/Monitor.Minor (1)ethanol, thioridazine. Either increases toxicity of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive CNS depression.eucalyptusMinor (1)thioridazine and eucalyptus both increase sedation. Minor/Significance Unknown.ezogabineMonitor Closely (1)ezogabine, thioridazine. Either increases toxicity of the other by QTc interval. Use Caution/Monitor. Slight and transient QT-prolongation observed with ezogabine, particularly when dose titrated to 1200 mg/day. QT interval should be monitored when ezogabine is prescribed with agents known to increase QT interval.fedratinibMonitor Closely (1)fedratinib will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.fenfluramineMonitor Closely (2)thioridazine, 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. thioridazine increases and fenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.fentanylSerious - Use Alternative (1)fentanyl, thioridazine. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.fentanyl intranasalSerious - Use Alternative (1)fentanyl intranasal, thioridazine. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.fentanyl transdermalSerious - Use Alternative (1)fentanyl transdermal, thioridazine. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with other CNS depressants, such as skeletal muscle relaxants, may cause respiratory depression, hypotension, profound sedation, coma, and/or death. Consider dose reduction of either or both agents to avoid serious adverse effects. Monitor for hypotension, respiratory depression, and profound sedation.fentanyl transmucosalSerious - Use Alternative (1)fentanyl transmucosal, thioridazine. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration with