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.ferric maltolMonitor Closely (1)ferric 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).fesoterodineMonitor Closely (3)fesoterodine 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.Minor (1)thioridazine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.fexinidazoleSerious - Use Alternative (1)fexinidazole and thioridazine both increase QTc interval. Avoid or Use Alternate Drug. Avoid coadministration of fexinidazole with drugs known to block potassium channels and/or prolong QT interval.fezolinetantContraindicated (1)thioridazine will increase the level or effect of fezolinetant by affecting hepatic enzyme CYP1A2 metabolism. Contraindicated. Fezolinetant AUC and peak plasma concentration are increased if coadministered with drugs that are weak, moderate, or strong CYP1A2 inhibitorsfingolimodContraindicated (1)fingolimod and thioridazine both increase QTc interval. Contraindicated.flavoxateMonitor Closely (3)flavoxate 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.flecainideMonitor Closely (2)thioridazine 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.fluconazoleSerious - Use Alternative (1)thioridazine and fluconazole both increase QTc interval. Avoid or Use Alternate Drug.fluoxetineContraindicated (3)thioridazine will increase the level or effect of fluoxetine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. thioridazine and fluoxetine both increase QTc interval. Contraindicated. fluoxetine increases levels of thioridazine by decreasing metabolism. Contraindicated. Risk of long QT syndrome.Serious - Use Alternative (1)fluoxetine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.fluphenazineMonitor Closely (2)fluphenazine 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.Serious - Use Alternative (1)fluphenazine and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)thioridazine will increase the level or effect of fluphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.flurazepamMonitor Closely (1)flurazepam and thioridazine both increase sedation. Use Caution/Monitor.fluvoxamineSerious - Use Alternative (2)fluvoxamine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP1A2 metabolism. Contraindicated. fluvoxamine and thioridazine both increase QTc interval. Contraindicated.formoterolMonitor Closely (1)thioridazine increases and formoterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)thioridazine and formoterol both increase QTc interval. Avoid or Use Alternate Drug.foscarnetMonitor Closely (1)thioridazine and foscarnet both increase QTc interval. Modify Therapy/Monitor Closely.fosinoprilMinor (1)thioridazine increases effects of fosinopril by unspecified interaction mechanism. Minor/Significance Unknown.fostemsavirMonitor Closely (1)thioridazine and fostemsavir both increase QTc interval. Use Caution/Monitor. QTc prolongation reported with higher than recommended doses of fostemsavir. gadobenateMonitor Closely (1)gadobenate and thioridazine both increase QTc interval. Use Caution/Monitor.galantamineMinor (1)thioridazine will increase the level or effect of galantamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.ganaxoloneMonitor Closely (1)thioridazine and ganaxolone both increase sedation. Use Caution/Monitor.gemifloxacinContraindicated (1)gemifloxacin and thioridazine both increase QTc interval. Contraindicated.gemtuzumabMonitor Closely (1)thioridazine and gemtuzumab both increase QTc interval. Use Caution/Monitor.gilteritinibContraindicated (1)gilteritinib and thioridazine both increase QTc interval. Contraindicated.givosiranSerious - Use Alternative (1)givosiran will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling.glasdegibSerious - Use Alternative (1)thioridazine and glasdegib both increase QTc interval. Avoid or Use Alternate Drug. If coadministration unavoidable, monitor for increased risk of QTc interval prolongation.glofitamabMonitor Closely (1)glofitamab, 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. .glycopyrrolateMonitor Closely (1)thioridazine increases effects of glycopyrrolate by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.Minor (1)thioridazine increases toxicity of glycopyrrolate by unknown mechanism. Minor/Significance Unknown.glycopyrrolate inhaledMonitor Closely (3)glycopyrrolate 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.Minor (1)thioridazine increases toxicity of glycopyrrolate inhaled by unknown mechanism. Minor/Significance Unknown.glycopyrronium tosylate topicalMonitor Closely (1)glycopyrronium 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.goserelinContraindicated (1)goserelin increases toxicity of thioridazine by QTc interval. Contraindicated. Increases risk of torsades de pointes.granisetronContraindicated (1)granisetron and thioridazine both increase QTc interval. Contraindicated.guanfacineMonitor Closely (1)guanfacine, thioridazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects; potential delirium.guselkumabMonitor Closely (1)guselkumab, 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.haloperidolMonitor Closely (3)thioridazine 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.Serious - Use Alternative (2)thioridazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. haloperidol will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.henbaneMonitor Closely (3)henbane 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.histrelinSerious - Use Alternative (1)histrelin increases toxicity of thioridazine by QTc interval. Avoid or Use Alternate Drug. Increases risk of torsades de pointes.homatropineMonitor Closely (3)homatropine 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.hydrocodoneMonitor Closely (1)thioridazine 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.Serious - Use Alternative (1)hydrocodone, thioridazine. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation. Increased risk of hypotension if ability to maintain blood pressure has been compromised by a reduced blood volume or concurrent administration of certain CNS depressant drugs (eg, phenothiazines or general anesthetics).hydromorphoneMonitor Closely (2)thioridazine 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.hydroxychloroquine sulfateSerious - Use Alternative (1)hydroxychloroquine sulfate and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.hydroxyzineContraindicated (1)hydroxyzine and thioridazine both increase QTc interval. Contraindicated.Monitor Closely (1)hydroxyzine and thioridazine both increase sedation. Use Caution/Monitor.hyoscyamineMonitor Closely (3)hyoscyamine 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 sprayMonitor Closely (3)thioridazine 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.ibutilideContraindicated (1)thioridazine and ibutilide both increase QTc interval. Contraindicated.iloperidoneMonitor Closely (4)thioridazine will increase the level or effect of iloperidone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. thioridazine and iloperidone both increase QTc interval. Modify Therapy/Monitor Closely. iloperidone and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. iloperidone and thioridazine both increase sedation. Use Caution/Monitor.imatinibSerious - Use Alternative (1)imatinib will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.imidaprilMinor (1)thioridazine increases effects of imidapril by unspecified interaction mechanism. Minor/Significance Unknown.imipramineContraindicated (1)thioridazine will increase the level or effect of imipramine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.Monitor Closely (1)thioridazine and imipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)thioridazine and imipramine both increase QTc interval. Avoid or Use Alternate Drug.Minor (2)imipramine, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects. imipramine, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.incobotulinumtoxinAMonitor Closely (1)thioridazine increases effects of incobotulinumtoxinA by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.indacaterol, inhaledMonitor Closely (1)indacaterol, 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.indapamideContraindicated (1)thioridazine and indapamide both increase QTc interval. Contraindicated.inotuzumabSerious - Use Alternative (1)inotuzumab and thioridazine both increase QTc interval. Avoid or Use Alternate Drug. If unable to avoid concomitant use, obtain ECGs and electrolytes before and after initiation of any drug known to prolong QTc, and periodically monitor as clinically indicated during treatment.insulin degludecMonitor Closely (1)thioridazine decreases effects of insulin degludec by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.insulin degludec/insulin aspartMonitor Closely (1)thioridazine decreases effects of insulin degludec/insulin aspart by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.insulin inhaledMonitor Closely (1)thioridazine decreases effects of insulin inhaled by Other (see comment). Use Caution/Monitor. Comment: Phenothiazines may increase blood glucose concentrations.ipratropiumMonitor Closely (3)ipratropium 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.isofluraneContraindicated (1)isoflurane and thioridazine both increase QTc interval. Contraindicated.isoproterenolMonitor Closely (2)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. thioridazine increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.itraconazoleSerious - Use Alternative (1)thioridazine and itraconazole both increase QTc interval. Avoid or Use Alternate Drug.ivosidenibSerious - Use Alternative (1)ivosidenib and thioridazine both increase QTc interval. Avoid or Use Alternate Drug. Avoid coadministration of QTc prolonging drugs with ivosidenib or replace with alternate therapies. If coadministration of a QTc prolonging drug is unavoidable, monitor for increased risk of QTc interval prolongation.ketamineMonitor Closely (1)ketamine and thioridazine both increase sedation. Use Caution/Monitor.ketoconazoleSerious - Use Alternative (1)thioridazine and ketoconazole both increase QTc interval. Avoid or Use Alternate Drug.ketotifen, ophthalmicMonitor Closely (1)thioridazine and ketotifen, ophthalmic both increase sedation. Use Caution/Monitor.lapatinibMonitor Closely (1)thioridazine and lapatinib both increase QTc interval. Modify Therapy/Monitor Closely.lasmiditanMonitor Closely (1)lasmiditan, 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.lefamulinSerious - Use Alternative