Use Caution/Monitor.tadalafilMonitor Closely (1)haloperidol will increase the level or effect of tadalafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors may reduce tadalafil clearance increasing systemic exposure to tadalafil; increased levels may result in increased associated adverse events. tamoxifenMonitor Closely (1)haloperidol decreases effects of tamoxifen by decreasing metabolism. Use Caution/Monitor. Inhibition of CYP2D6 metabolism to tamoxifen's active metabolite, endoxifen.tamsulosinMonitor Closely (2)haloperidol increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A. haloperidol increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.tapentadolMonitor Closely (1)tapentadol and haloperidol both increase sedation. Use Caution/Monitor.tazemetostatMonitor Closely (1)tazemetostat will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of tazemetostat with moderate CYP3A4 inhibitors. If coadministration is unavoidable, reduce tazemetostat current dose (see drug monograph Dosage Modifications). tecovirimatMonitor Closely (1)tecovirimat will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.teduglutideMonitor Closely (1)teduglutide increases levels of haloperidol 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)haloperidol and telavancin both increase QTc interval. Modify Therapy/Monitor Closely.temazepamMonitor Closely (1)temazepam and haloperidol both increase sedation. Use Caution/Monitor.terbinafineMonitor Closely (1)terbinafine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.terbutalineMonitor Closely (1)haloperidol increases and terbutaline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.tetrabenazineMonitor Closely (1)haloperidol and tetrabenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)tetrabenazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.tezacaftorMonitor Closely (1)haloperidol will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.thioridazineMonitor 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.thiothixeneMonitor Closely (3)haloperidol and thiothixene both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. haloperidol and thiothixene both increase sedation. Use Caution/Monitor. haloperidol and thiothixene both increase QTc interval. Use Caution/Monitor.timololMonitor Closely (1)haloperidol will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.tinidazoleMonitor Closely (1)haloperidol will increase the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.tiotropiumMonitor Closely (3)tiotropium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. tiotropium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. haloperidol increases effects of tiotropium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.tipranavirMonitor Closely (2)tipranavir will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. tipranavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.tofacitinibMonitor Closely (1)haloperidol increases levels of tofacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No specific dose adjustment recommended when tofacitinib coadministered with moderate CYP3A4 inhibitors; decrease tofacitinib dose if coadministered with both moderate CYP3A4 and potent CYP2C19 inhibitors.tolterodineMonitor Closely (3)tolterodine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. tolterodine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. haloperidol increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.Minor (1)haloperidol will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.topiramateMonitor Closely (1)haloperidol and topiramate both increase sedation. Modify Therapy/Monitor Closely.toremifeneSerious - Use Alternative (1)haloperidol and toremifene both increase QTc interval. Avoid or Use Alternate Drug. Concurrent use of toremifene with agents causing QT prolongation should be avoided. If concomitant use is required it's recommended that toremifene be interrupted. If interruption not possible, patients requiring therapy with a drug that prolongs QT should be closely monitored. ECGs should be obtained for high risk patients.trabectedinMonitor Closely (1)haloperidol will increase the level or effect of trabectedin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.tramadolMonitor Closely (1)tramadol and haloperidol both increase sedation. Use Caution/Monitor.tranylcypromineMonitor Closely (1)tranylcypromine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).trazodoneMonitor Closely (1)haloperidol and trazodone both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)trazodone and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.triazolamMonitor Closely (1)triazolam and haloperidol both increase sedation. Use Caution/Monitor.triclabendazoleMonitor Closely (1)triclabendazole and haloperidol both increase QTc interval. Use Caution/Monitor.triclofosMonitor Closely (1)triclofos and haloperidol both increase sedation. Use Caution/Monitor.trifluoperazineMonitor Closely (2)haloperidol and trifluoperazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. haloperidol and trifluoperazine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)trifluoperazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of trifluoperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.trihexyphenidylMonitor Closely (1)haloperidol increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.trimethoprimMonitor Closely (1)haloperidol and trimethoprim both increase QTc interval. Modify Therapy/Monitor Closely.trimipramineMonitor Closely (1)haloperidol and trimipramine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)trimipramine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.triprolidineMonitor Closely (1)triprolidine and haloperidol both increase sedation. Use Caution/Monitor.triptorelinMonitor Closely (1)triptorelin increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Increases risk of torsades de pointes.tropisetronMonitor Closely (1)haloperidol and tropisetron both increase QTc interval. Modify Therapy/Monitor Closely.Minor (1)haloperidol will increase the level or effect of tropisetron by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.trospium chlorideMonitor Closely (3)trospium chloride decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. trospium chloride decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. haloperidol increases effects of trospium chloride by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.tucatinibSerious - Use Alternative (1)tucatinib will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.umeclidinium bromide/vilanterol inhaledSerious - Use Alternative (1)haloperidol increases toxicity of umeclidinium bromide/vilanterol inhaled by QTc interval. Avoid or Use Alternate Drug. Exercise extreme caution when vilanterol coadministered with drugs that prolong QTc interval; adrenergic agonist effects on the cardiovascular system may be potentiated.valbenazineMonitor Closely (1)valbenazine and haloperidol both increase QTc interval. Use Caution/Monitor.vandetanibSerious - Use Alternative (1)haloperidol, vandetanib. Either increases toxicity of the other by QTc interval. Avoid or Use Alternate Drug. Avoid coadministration with drugs known to prolong QT interval; if a drug known to prolong QT interval must be used, more frequent ECG monitoring is recommended.vardenafilMonitor Closely (2)haloperidol will increase the level or effect of vardenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Vardenafil dose may need to be reduced if coadministered with moderate or strong CYP3A4 inhibitors haloperidol and vardenafil both increase QTc interval. Use Caution/Monitor.vecuroniumMonitor Closely (3)vecuronium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. vecuronium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. haloperidol increases effects of vecuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.vemurafenibSerious - Use Alternative (1)vemurafenib and haloperidol both increase QTc interval. Avoid or Use Alternate Drug. Concomitant use of vemurafenib with drugs that prolong QT interval is not recommended.venetoclaxSerious - Use Alternative (1)haloperidol will increase the level or effect of venetoclax by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If a moderate CYP3A inhibitor must be used, reduce the venetoclax dose by at least 50%. Monitor more closely for signs of venetoclax toxicities.venlafaxineMonitor Closely (3)venlafaxine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. venlafaxine, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction). haloperidol and venlafaxine both increase QTc interval. Modify Therapy/Monitor Closely.vilanterol/fluticasone furoate inhaledSerious - Use Alternative (1)haloperidol increases toxicity of vilanterol/fluticasone furoate inhaled by QTc interval. Avoid or Use Alternate Drug. Exercise extreme caution when vilanterol coadministered with drugs that prolong QTc interval; adrenergic agonist effects on the cardiovascular system may be potentiated.vilazodoneMonitor Closely (1)vilazodone, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).voclosporinMonitor Closely (2)voclosporin, haloperidol. Either increases effects of the other by QTc interval. Use Caution/Monitor. haloperidol will increase the level or effect of voclosporin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce voclosporin daily dosage to 15.8 mg PO in AM and 7.9 mg PO in PM.voriconazoleMonitor Closely (2)voriconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. haloperidol and voriconazole both increase QTc interval. Modify Therapy/Monitor Closely.vorinostatMonitor Closely (1)haloperidol and vorinostat both increase QTc interval. Use Caution/Monitor.voxelotorSerious - Use Alternative (1)voxelotor will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.xylometazolineMonitor Closely (1)haloperidol increases and xylometazoline decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.yohimbineMonitor Closely (1)haloperidol increases and yohimbine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.zanubrutinibMonitor Closely (1)haloperidol will increase the level or effect of zanubrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce zanubrutinib (a CYP3A4 substrate) to 80 mg PO BID to when coadministered with a moderate CYP3A4 inhibitor. Interrupt dose as recommended for adverse reactions. After discontinuing the CYP3A4 inhibitor, resume previous dose of zanubrutinib. ziconotideMonitor Closely (1)haloperidol and ziconotide both increase sedation. Use Caution/Monitor.ziprasidoneMonitor Closely (2)haloperidol and ziprasidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. haloperidol and ziprasidone both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)haloperidol and ziprasidone both increase QTc interval. Avoid or Use Alternate Drug.zolmitriptanMonitor Closely (1)zolmitriptan, haloperidol. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotics may enhance serotonergic effect of serotonin modulators, which may result in serotonin syndrome. Monitor for evidence of serotonin toxicity (eg, mental status changes, autonomic instability, and neuromuscular hyperactivity) or neuroleptic malignant syndrome (eg, hyperthermia, muscle rigidity, autonomic dysfunction).zotepineMonitor Closely (2)haloperidol and zotepine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. haloperidol and zotepine both increase sedation. Use Caution/Monitor. Frequency Not Defined Extrapyramidal symptoms Akathisia Dystonia Muscle stiffness Neuroleptic malignant syndrome (NMS; infrequent but serious) Parkinsonism Tardive dyskinesia Common Anticholinergic effects Sedation Weight gain Erectile dysfunction Oligomenorrhea or amenorrhea Less common Orthostatic hypotension (after IM injection), tachycardia Agitation, anxiety, cerebral edema, depression, dizziness, euphoria, headache, insomnia, poikilothermia, restlessness, weakness, confusion Anorexia, constipation,