If serotonin syndrome occurs, discontinue dextroamphetamine transdermal and CYP2D6 inhibitor.dextromoramidedextromoramide and thioridazine both increase sedation. Use Caution/Monitor.diamorphinediamorphine and thioridazine both increase sedation. Use Caution/Monitor.diazepamdiazepam and thioridazine both increase sedation. Use Caution/Monitor.dicyclominedicyclomine 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.diethylpropionthioridazine increases and diethylpropion decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.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.difelikefalindifelikefalin and thioridazine both increase sedation. Use Caution/Monitor.difenoxin hcldifenoxin hcl and thioridazine both increase sedation. Use Caution/Monitor.dimenhydrinatedimenhydrinate and thioridazine both increase sedation. Use Caution/Monitor.diphenhydraminediphenhydramine 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.diphenoxylate hcldiphenoxylate hcl and thioridazine both increase sedation. Use Caution/Monitor.dipipanonedipipanone and thioridazine both increase sedation. Use Caution/Monitor.dobutaminethioridazine increases and dobutamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.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.dolasetronthioridazine and dolasetron both increase QTc interval. Modify Therapy/Monitor Closely.donepezil transdermaldonepezil transdermal, thioridazine. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.dopaminethioridazine increases and dopamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.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.dopexaminethioridazine increases and dopexamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dosulepinthioridazine and dosulepin both increase sedation. Use Caution/Monitor.doxepinthioridazine and doxepin both increase sedation. Use Caution/Monitor.doxylaminedoxylamine and thioridazine both increase sedation. Use Caution/Monitor.droperidoldroperidol 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.eliglustateliglustat 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 DFelvitegravir/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.epcoritamabepcoritamab, 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. .ephedrinethioridazine increases and ephedrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.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.epinephrinethioridazine increases and epinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.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.epinephrine racemicthioridazine increases and epinephrine racemic decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.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.esketamine intranasalesketamine intranasal, thioridazine. Either increases toxicity of the other by sedation. Modify Therapy/Monitor Closely.estazolamestazolam and thioridazine both increase sedation. Use Caution/Monitor.ethanolthioridazine and ethanol both increase sedation. Use Caution/Monitor.ezogabineezogabine, 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.fedratinibfedratinib 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.fenfluraminethioridazine increases and fenfluramine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.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.ferric maltolferric maltol, thioridazine. Either increases levels of the other by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Coadministration of ferric maltol with certain oral medications may decrease the bioavailability of either ferric maltol and some oral drugs. For oral drugs where reductions in bioavailability may cause clinically significant effects on its safety or efficacy, separate administration of ferric maltol from these drugs. Duration of separation may depend on the absorption of the medication concomitantly administered (eg, time to peak concentration, whether the drug is an immediate or extended release product).fesoterodinefesoterodine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.flavoxateflavoxate decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.flavoxate decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of flavoxate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.flecainidethioridazine will increase the level or effect of flecainide by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.thioridazine and flecainide both increase QTc interval. Modify Therapy/Monitor Closely.fluphenazinefluphenazine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.fluphenazine and thioridazine both increase sedation. Use Caution/Monitor.flurazepamflurazepam and thioridazine both increase sedation. Use Caution/Monitor.formoterolthioridazine increases and formoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.foscarnetthioridazine and foscarnet both increase QTc interval. Modify Therapy/Monitor Closely.fostemsavirthioridazine and fostemsavir both increase QTc interval. Use Caution/Monitor. QTc prolongation reported with higher than recommended doses of fostemsavir. gadobenategadobenate and thioridazine both increase QTc interval. Use Caution/Monitor.ganaxolonethioridazine and ganaxolone both increase sedation. Use Caution/Monitor.gemtuzumabthioridazine and gemtuzumab both increase QTc interval. Use Caution/Monitor.glofitamabglofitamab, thioridazine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Glofitamab 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. .glycopyrrolatethioridazine increases effects of glycopyrrolate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.glycopyrrolate inhaledglycopyrrolate inhaled decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.glycopyrrolate inhaled decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of glycopyrrolate inhaled by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.glycopyrronium tosylate topicalglycopyrronium tosylate topical, thioridazine. 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.guanfacineguanfacine, thioridazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.guselkumabguselkumab, 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 guselkumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.haloperidolthioridazine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.haloperidol and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.haloperidol and thioridazine both increase sedation. Use Caution/Monitor.henbanehenbane decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.henbane decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of henbane by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.homatropinehomatropine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.homatropine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of homatropine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.hydrocodonethioridazine will increase the level or effect of hydrocodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.hydromorphonethioridazine will increase the level or effect of hydromorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.hydromorphone and thioridazine both increase sedation. Use Caution/Monitor.hydroxyzinehydroxyzine and thioridazine both increase sedation. Use Caution/Monitor.hyoscyaminehyoscyamine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.hyoscyamine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of hyoscyamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.hyoscyamine spraythioridazine increases effects of hyoscyamine spray by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.hyoscyamine spray decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.hyoscyamine spray decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.iloperidonethioridazine will increase the level or effect of iloperidone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.iloperidone and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.thioridazine and iloperidone both increase QTc interval. Modify Therapy/Monitor Closely.iloperidone and thioridazine both increase sedation. Use Caution/Monitor.imipraminethioridazine and imipramine both increase sedation. Use Caution/Monitor.incobotulinumtoxinAthioridazine increases effects of incobotulinumtoxinA by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.indacaterol, inhaledindacaterol, inhaled, thioridazine. QTc interval. Use Caution/Monitor. Drugs that are known to prolong the QTc interval may have an increased the risk of ventricular arrhythmias.insulin degludecthioridazine decreases effects of insulin degludec by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.insulin degludec/insulin aspartthioridazine decreases effects of insulin degludec/insulin aspart by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.insulin inhaledthioridazine decreases effects of insulin inhaled by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.ipratropiumipratropium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.ipratropium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of ipratropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.isoproterenolthioridazine increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, isoproterenol. 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.ketamineketamine and thioridazine both increase sedation. Use Caution/Monitor.ketotifen, ophthalmicthioridazine and ketotifen, ophthalmic both increase sedation. Use Caution/Monitor.lapatinibthioridazine and lapatinib both increase QTc interval. Modify Therapy/Monitor Closely.lasmiditanlasmiditan, thioridazine. 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.lemborexantlemborexant will increase the level or effect of thioridazine by sedation. Modify Therapy/Monitor Closely. Dosage adjustment may be necessary if lemborexant is coadministered with other CNS depressants because of potentially additive effects.lenvatinibthioridazine and lenvatinib both increase QTc interval. Use Caution/Monitor. Lenvatinib prescribing information recommends monitoring ECG closely when coadministered with QT prolonging drugs.levalbuterolthioridazine increases and levalbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.levofloxacinthioridazine and levofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.levorphanollevorphanol and thioridazine both increase sedation. Use Caution/Monitor.liraglutidethioridazine, liraglutide. Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase or decrease glucose levels, monitor therapy closely when these agents are concurrently administered.lisdexamfetaminethioridazine increases and lisdexamfetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, lisdexamfetamine. 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.lithiumlithium, thioridazine. Other (see comment). Use Caution/Monitor. Comment: Risk of neurotoxicity. Multiple mechanisms involved.lofepraminethioridazine will increase the level or effect of lofepramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.thioridazine and lofepramine both increase sedation. Use Caution/Monitor.lofexidinethioridazine and lofexidine both increase sedation. Use Caution/Monitor.thioridazine will increase the level