moderate CYP3A4 inhibitors may increase ivosidenib plasma concentrations, thus increasing the risk of QTc prolongation. Monitor for increased risk of QTc interval prolongation.ketamineketamine and haloperidol both increase sedation. Use Caution/Monitor.ketoconazoleketoconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ketotifen, ophthalmichaloperidol and ketotifen, ophthalmic both increase sedation. Use Caution/Monitor.lapatinibhaloperidol and lapatinib both increase QTc interval. Modify Therapy/Monitor Closely.lasmiditanlasmiditan, haloperidol. 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, haloperidol. Either increases effects of the other by sedation. Modify Therapy/Monitor Closely. Dosage adjustment may be necessary if lemborexant is coadministered with other CNS depressants because of potentially additive effects.lenacapavirlenacapavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.lenvatinibhaloperidol and lenvatinib both increase QTc interval. Use Caution/Monitor. Lenvatinib prescribing information recommends monitoring ECG closely when coadministered with QT prolonging drugs.letermovirletermovir increases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.leuprolideleuprolide increases toxicity of haloperidol by QTc interval. Use Caution/Monitor. Increases risk of torsades de pointes.levalbuterolhaloperidol increases and levalbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.levamlodipinehaloperidol will increase the level or effect of levamlodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate and strong CYP3A inhibitors results in increased systemic exposure to amlodipine and may require dose reduction. Monitor for symptoms of hypotension and edema when amlodipine is coadministered with CYP3A inhibitors to determine the need for dose adjustment.levofloxacinhaloperidol and levofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.levoketoconazolelevoketoconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.levomilnacipranlevomilnacipran, 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).levorphanollevorphanol and haloperidol both increase sedation. Use Caution/Monitor.linezolidlinezolid, 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).lisdexamfetaminehaloperidol increases and lisdexamfetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.lithiumlithium, haloperidol. Other (see comment). Use Caution/Monitor. Comment: Risk of neurotoxicity. Multiple mechanisms involved.lithium, 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).lithium and haloperidol both increase QTc interval. Use Caution/Monitor.lofepraminehaloperidol will increase the level or effect of lofepramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.haloperidol and lofepramine both increase sedation. Use Caution/Monitor.lofexidinehaloperidol and lofexidine both increase sedation. Use Caution/Monitor.loprazolamloprazolam and haloperidol both increase sedation. Use Caution/Monitor.lorazepamlorazepam and haloperidol both increase sedation. Use Caution/Monitor.lorcaserinlorcaserin will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.lorcaserin, 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).lorlatiniblorlatinib will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.lormetazepamlormetazepam and haloperidol both increase sedation. Use Caution/Monitor.loxapinehaloperidol and loxapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.haloperidol and loxapine both increase sedation. Use Caution/Monitor.loxapine inhaledhaloperidol and loxapine inhaled both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.haloperidol and loxapine inhaled both increase sedation. Use Caution/Monitor.lumateperonehaloperidol will increase the level or effect of lumateperone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce lumateperone dose to 21 mg/day if coadministered with moderate CYP3A4 inhibitors.lurasidonelurasidone, haloperidol. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Potential for increased CNS depressant effects when used concurrently; monitor for increased adverse effects and toxicity.maprotilinehaloperidol and maprotiline both increase sedation. Use Caution/Monitor.maravirocmaraviroc will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.marijuanamarijuana will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.haloperidol and marijuana both increase sedation. Use Caution/Monitor.mavacamtenhaloperidol will increase the level or effect of mavacamten by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Inititiation of moderate CYP3A4 inhibitors may require decreased mavacamten dose. meclizinemeclizine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.meclizine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.haloperidol increases effects of meclizine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.mefloquinehaloperidol and mefloquine both increase QTc interval. Use Caution/Monitor.haloperidol will increase the level or effect of mefloquine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.melatoninhaloperidol and melatonin both increase sedation. Use Caution/Monitor.meperidinemeperidine and haloperidol both increase sedation. Use Caution/Monitor.meperidine, 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).meprobamatehaloperidol and meprobamate both increase sedation. Use Caution/Monitor.metaproterenolhaloperidol increases and metaproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.metaxalonemetaxalone and haloperidol both increase sedation. Use Caution/Monitor.methadonehaloperidol and methadone both increase QTc interval. Modify Therapy/Monitor Closely.methadone and haloperidol both increase sedation. Use Caution/Monitor.methadone, 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).methamphetaminehaloperidol will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.haloperidol increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.methocarbamolmethocarbamol and haloperidol both increase sedation. Use Caution/Monitor.methscopolaminemethscopolamine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.methscopolamine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor.haloperidol increases effects of methscopolamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.methylenedioxymethamphetaminehaloperidol increases and methylenedioxymethamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.methylergonovinemethylergonovine, 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).methylphenidatehaloperidol increases toxicity of methylphenidate by pharmacodynamic antagonism. Use Caution/Monitor. Closely monitor for signs of altered clinical response to either methylphenidate or an antipsychotic when using these drugs in combination.metoclopramidehaloperidol and metoclopramide both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.metoprololhaloperidol will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.mexiletinehaloperidol will increase the level or effect of mexiletine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised haloperidol and mexiletine both increase QTc interval. Use Caution/Monitor.midazolammidazolam and haloperidol both increase sedation. Use Caution/Monitor.midazolam intranasalmidazolam intranasal, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase the risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.midodrinehaloperidol increases and midodrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.mifepristonemifepristone, haloperidol. QTc interval. Modify Therapy/Monitor Closely. Use alternatives if available.milnacipranmilnacipran, 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).mirabegronmirabegron will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.mirtazapinehaloperidol and mirtazapine both increase sedation. Use Caution/Monitor.mirtazapine and haloperidol both increase QTc interval. Use Caution/Monitor.mitotanemitotane decreases levels of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.modafinilhaloperidol increases and modafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.morphinehaloperidol will increase the level or effect of morphine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.morphine and haloperidol both increase sedation. Use Caution/Monitor.motherworthaloperidol and motherwort both increase sedation. Use Caution/Monitor.moxonidinehaloperidol and moxonidine both increase sedation. Use Caution/Monitor.nabilonehaloperidol and nabilone both increase sedation. Use Caution/Monitor.nafcillinnafcillin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nalbuphinenalbuphine and haloperidol both increase sedation. Use Caution/Monitor.naldemedinehaloperidol increases levels of naldemedine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor naldemedine for potential adverse effects if coadministered with strong or moderate CYP3A4 inhibitors.naratriptannaratriptan, 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).nebivololhaloperidol will increase the level or effect of nebivolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.nefazodonenefazodone will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nelfinavirnelfinavir will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nilotinibnilotinib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.norepinephrinehaloperidol increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.norgestrelhaloperidol will increase the level or effect of norgestrel by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Strong or moderate CYP3A4 inhibitors may increase systemic concentration of norgestrel, which may increase risk for adverse effects nortriptylinehaloperidol and nortriptyline both increase sedation. Use Caution/Monitor.ofloxacinhaloperidol and ofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.olanzapinehaloperidol and olanzapine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.haloperidol and olanzapine both increase sedation. Use Caution/Monitor.haloperidol and olanzapine both increase QTc interval. Use Caution/Monitor.oliceridinehaloperidol will increase the level or effect of oliceridine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. oliceridine, haloperidol. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. 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.olodaterol inhaledhaloperidol and olodaterol inhaled both increase QTc interval. Use Caution/Monitor. Drugs that prolong the QTc interval and may potentiate the effects of beta2 agonists on the cardiovascular system; increased risk of ventricular arrhythmiasonabotulinumtoxinAonabotulinumtoxinA decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both