or Use Alternate Drug.Minor (2)protriptyline, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects. protriptyline, thioridazine. Either increases levels of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.pseudoephedrineMonitor Closely (1)thioridazine, 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.pyrimethamineMinor (1)pyrimethamine increases levels of thioridazine by decreasing metabolism. Minor/Significance Unknown.quazepamMonitor Closely (1)quazepam and thioridazine both increase sedation. Use Caution/Monitor.quetiapineMonitor Closely (3)quetiapine 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.quinacrineSerious - Use Alternative (1)quinacrine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.quinaprilMinor (1)thioridazine increases effects of quinapril by unspecified interaction mechanism. Minor/Significance Unknown.quinidineContraindicated (1)thioridazine and quinidine both increase QTc interval. Contraindicated.Serious - Use Alternative (2)quinidine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. quinidine, thioridazine. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Additive cardiac effects.quinineContraindicated (1)thioridazine and quinine both increase QTc interval. Contraindicated.ramelteonMonitor Closely (1)thioridazine and ramelteon both increase sedation. Use Caution/Monitor.ramiprilMinor (1)thioridazine increases effects of ramipril by unspecified interaction mechanism. Minor/Significance Unknown.ranolazineMonitor Closely (1)thioridazine and ranolazine both increase QTc interval. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)ranolazine will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.rapacuroniumMonitor Closely (3)rapacuronium 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.ribociclibSerious - Use Alternative (1)ribociclib and thioridazine both increase QTc interval. Avoid or Use Alternate Drug.rilpivirineMonitor Closely (1)rilpivirine 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.rimabotulinumtoxinBMonitor Closely (1)thioridazine, 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.risperidoneMonitor Closely (3)thioridazine and risperidone both increase QTc interval. Modify Therapy/Monitor Closely. risperidone and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. risperidone and thioridazine both increase sedation. Use Caution/Monitor.Minor (1)thioridazine will increase the level or effect of risperidone by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.ritlecitinibMonitor Closely (1)ritlecitinib 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. ritonavirSerious - Use Alternative (1)ritonavir will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.rocuroniumMonitor Closely (3)rocuronium 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.rolapitantContraindicated (1)rolapitant will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated. Rolapitant moderately inhibits CYP2D6. Coadministration with thioridazine, a CYP2D6 substrate, causes a significant increase in thioridazine plasma concentration that may result in QT prolongation and torsades de pointes.romidepsinMonitor Closely (1)thioridazine and romidepsin both increase QTc interval. Modify Therapy/Monitor Closely.ropeginterferon alfa 2bMonitor Closely (1)ropeginterferon 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.ropiniroleSerious - Use Alternative (1)thioridazine decreases effects of ropinirole by pharmacodynamic antagonism. Contraindicated.safinamideSerious - Use Alternative (1)thioridazine decreases effects of safinamide by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Dopamine antagonists may decrease safinamide effects and exacerbate Parkinson disease symptoms.sageMinor (1)thioridazine and sage both increase sedation. Minor/Significance Unknown.salmeterolMonitor Closely (1)thioridazine increases and salmeterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.saquinavirMonitor Closely (1)saquinavir, thioridazine. Either increases toxicity of the other by QTc interval. Modify Therapy/Monitor Closely. Use alternatives if available.scopolamineMonitor Closely (3)scopolamine 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.scullcapMonitor Closely (1)thioridazine and scullcap both increase sedation. Use Caution/Monitor.secobarbitalMonitor Closely (1)secobarbital and thioridazine both increase sedation. Use Caution/Monitor.Minor (1)thioridazine decreases levels of secobarbital by unspecified interaction mechanism. Minor/Significance Unknown.selinexorSerious - Use Alternative (1)selinexor, thioridazine. unspecified interaction mechanism. Avoid or Use Alternate Drug. Patients treated with selinexor may experience neurological toxicities. Avoid taking selinexor with other medications that may cause dizziness or confusion.selpercatinibMonitor Closely (1)selpercatinib increases toxicity of thioridazine by QTc interval. Use Caution/Monitor.serdexmethylphenidate/dexmethylphenidateMonitor Closely (1)thioridazine, 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.sertralineContraindicated (2)sertraline increases levels of thioridazine by decreasing metabolism. Contraindicated. Risk of long QT syndrome. sertraline and thioridazine both increase QTc interval. Contraindicated.Serious - Use Alternative (1)sertraline will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Contraindicated.sevofluraneContraindicated (1)sevoflurane and thioridazine both increase QTc interval. Contraindicated.Monitor Closely (1)sevoflurane and thioridazine both increase sedation. Use Caution/Monitor.shepherd's purseMonitor Closely (1)thioridazine and shepherd's purse both increase sedation. Use Caution/Monitor.siponimodContraindicated (1)siponimod and thioridazine both increase QTc interval. Contraindicated.smokingMonitor Closely (1)smoking decreases levels of thioridazine by increasing metabolism. Use Caution/Monitor. Interaction mainly seen w/chlorpromazine & thioridazine, but may occur w/other phenothiazines.sodium oxybateSerious - Use Alternative (1)thioridazine, sodium oxybate. Either increases effects 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.sodium sulfate/?magnesium sulfate/potassium chlorideMonitor Closely (1)sodium 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 sulfateMonitor Closely (1)sodium 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. .solifenacinContraindicated (1)solifenacin and thioridazine both increase QTc interval. Contraindicated.Monitor Closely (3)solifenacin 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.somapacitanMonitor Closely (1)somapacitan 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 substratessomatrogonMonitor Closely (1)somatrogon 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 substratessomatropinMonitor Closely (1)somatropin 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 substratessorafenibContraindicated (1)sorafenib and thioridazine both increase QTc interval. Contraindicated.sotalolContraindicated (1)thioridazine and sotalol both increase QTc interval. Contraindicated.stiripentolMonitor Closely (1)stiripentol, 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.sufentanilMonitor Closely (1)sufentanil and thioridazine both increase sedation. Use Caution/Monitor.sulfamethoxazoleMonitor Closely (1)thioridazine and sulfamethoxazole both increase QTc interval. Modify Therapy/Monitor Closely.sunitinibContraindicated (1)sunitinib and thioridazine both increase QTc interval. Contraindicated.tacrolimusContraindicated (1)tacrolimus and thioridazine both increase QTc interval. Contraindicated.tamsulosinMonitor Closely (1)thioridazine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.tapentadolMonitor Closely (1)tapentadol and thioridazine both increase sedation. Use Caution/Monitor.teclistamabMonitor Closely (1)teclistamab 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. teduglutideMonitor Closely (1)teduglutide 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.telavancinMonitor Closely (1)thioridazine and telavancin both increase QTc interval. Modify Therapy/Monitor Closely.temazepamMonitor Closely (1)temazepam and thioridazine both increase sedation. Use Caution/Monitor.terbinafineMonitor Closely (1)terbinafine 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.terbutalineMonitor Closely (1)thioridazine increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.tetrabenazineContraindicated (1)tetrabenazine and thioridazine both increase QTc interval. Contraindicated.Monitor Closely (1)thioridazine and tetrabenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely.thiothixeneMonitor Closely (2)thioridazine 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.timololMonitor Closely (1)thioridazine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.tiotropiumMonitor Closely (3)tiotropium 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.tipranavirSerious - Use Alternative (1)tipranavir will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.tobacco useMonitor Closely (1)tobacco use decreases levels of thioridazine by increasing metabolism. Use Caution/Monitor. Interaction mainly seen w/chlorpromazine & thioridazine, but may occur w/other phenothiazines.tolterodineMonitor Closely (3)tolterodine 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.Minor (1)thioridazine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.topiramateMonitor Closely (1)thioridazine and topiramate both increase sedation. Modify Therapy/Monitor Closely.toremifeneContraindicated (1)thioridazine and toremifene both increase QTc interval. Contraindicated. Concurrent use of thioridazine with other agents that prolong QTc interval is contraindicated.tramadolMonitor Closely (3)thioridazine 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.trandolaprilMinor (1)thioridazine increases effects of trandolapril by unspecified interaction mechanism. Minor/Significance Unknown.trazodoneMonitor Closely (1)thioridazine and trazodone both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)thioridazine and trazodone both increase QTc interval. Avoid or Use Alternate Drug.Minor (2)trazodone, thioridazine. Either increases toxicity of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive hypotensive effects. trazodone, thioridazine. Either increases levels of the other by decreasing metabolism. Minor/Significance Unknown. Additive anticholinergic effects.tretinoinSerious - Use Alternative (1)thioridazine, tretinoin. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.tretinoin topicalSerious - Use Alternative (1)thioridazine, tretinoin topical. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.triazolamMonitor Closely (1)triazolam and thioridazine both increase sedation. Use Caution/Monitor.triclabendazoleMonitor Closely (1)triclabendazole and thioridazine both increase QTc interval. Use Caution/Monitor.triclofosMonitor Closely (1)triclofos and thioridazine both increase sedation. Use Caution/Monitor.trifluoperazineMonitor Closely (2)thioridazine and trifluoperazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome.