of oliceridine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. 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. olodaterol inhaledMonitor Closely (1)haloperidol 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 arrhythmiasolopatadine intranasalSerious - Use Alternative (1)haloperidol and olopatadine intranasal both increase sedation. Avoid or Use Alternate Drug. Coadministration increases risk of CNS depression, which can lead to additive impairment of psychomotor performance and cause daytime impairment. omaveloxoloneSerious - Use Alternative (1)haloperidol will increase the level or effect of omaveloxolone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unavoidable, reduce omaveloxolone dose to 100 mg/day. Closely monitor for adverse effects. If adverse effects emerge, further reduce to 50 mg/day. onabotulinumtoxinAMonitor Closely (3)onabotulinumtoxinA decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. onabotulinumtoxinA decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. haloperidol increases effects of onabotulinumtoxinA by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.ondansetronSerious - Use Alternative (1)haloperidol and ondansetron both increase QTc interval. Avoid or Use Alternate Drug. Avoid with congenital long QT syndrome; ECG monitoring recommended with concomitant medications that prolong QT interval, electrolyte abnormalities, CHF, or bradyarrhythmias.opium tinctureMonitor Closely (1)opium tincture and haloperidol both increase sedation. Use Caution/Monitor.orphenadrineMonitor Closely (1)orphenadrine and haloperidol both increase sedation. Use Caution/Monitor.osilodrostatMonitor Closely (1)osilodrostat and haloperidol both increase QTc interval. Use Caution/Monitor.osimertinibMonitor Closely (1)osimertinib and haloperidol both increase QTc interval. Use Caution/Monitor. Conduct periodic monitoring with ECGs and electrolytes in patients taking drugs known to prolong the QTc interval.oxaliplatinMonitor Closely (1)oxaliplatin will increase the level or effect of haloperidol by Other (see comment). Use Caution/Monitor. Monitor for ECG changes if therapy is initiated in patients with drugs known to prolong QT interval.Serious - Use Alternative (1)oxaliplatin and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.oxazepamMonitor Closely (1)oxazepam and haloperidol both increase sedation. Use Caution/Monitor.oxybutyninMonitor Closely (3)oxybutynin decreases effects of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. oxybutynin decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. haloperidol increases effects of oxybutynin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxybutynin topicalMonitor Closely (3)oxybutynin topical decreases effects of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. oxybutynin topical decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. haloperidol increases effects of oxybutynin topical by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxybutynin transdermalMonitor Closely (3)oxybutynin transdermal decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. oxybutynin transdermal decreases effects of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. haloperidol increases effects of oxybutynin transdermal by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxycodoneMonitor Closely (2)haloperidol will increase the level or effect of oxycodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. oxycodone and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol decreases effects of oxycodone by decreasing metabolism. Minor/Significance Unknown. Decreased conversion of oxycodone to active metabolite morphine.oxymorphoneMonitor Closely (2)haloperidol will increase the level or effect of oxymorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. oxymorphone and haloperidol both increase sedation. Use Caution/Monitor.ozanimodMonitor Closely (1)ozanimod and haloperidol both increase QTc interval. Modify Therapy/Monitor Closely. The potential additive effects on heart rate, treatment with ozanimod should generally not be initiated in patients who are concurrently treated with QT prolonging drugs with known arrhythmogenic properties.pacritinibSerious - Use Alternative (1)haloperidol will increase the level or effect of pacritinib by affecting hepatic enzyme CYP2E1 metabolism. Avoid or Use Alternate Drug.palbociclibMonitor Closely (1)haloperidol will increase the level or effect of palbociclib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.paliperidoneMonitor Closely (3)haloperidol and paliperidone both increase QTc interval. Modify Therapy/Monitor Closely. haloperidol and paliperidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. haloperidol and paliperidone both increase sedation. Use Caution/Monitor.pancuroniumMonitor Closely (3)pancuronium decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. pancuronium decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. haloperidol increases effects of pancuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.panobinostatSerious - Use Alternative (1)haloperidol and panobinostat both increase QTc interval. Avoid or Use Alternate Drug. Panobinostat is known to significantly prolong QT interval. Panobinostat prescribing information states use with drugs known to prolong QTc is not recommended.papaveretumMonitor Closely (1)papaveretum and haloperidol both increase sedation. Use Caution/Monitor.papaverineMonitor Closely (1)haloperidol and papaverine both increase sedation. Use Caution/Monitor.parecoxibMonitor Closely (1)parecoxib will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.paroxetineMonitor Closely (3)paroxetine, 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 paroxetine both increase QTc interval. Modify Therapy/Monitor Closely. haloperidol will increase the level or effect of paroxetine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)paroxetine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.pasireotideMonitor Closely (1)haloperidol and pasireotide both increase QTc interval. Modify Therapy/Monitor Closely.pazopanibMonitor Closely (1)haloperidol and pazopanib both increase QTc interval. Use Caution/Monitor.peginterferon alfa 2bMonitor Closely (1)peginterferon alfa 2b, haloperidol. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.pemigatinibSerious - Use Alternative (1)haloperidol will increase the level or effect of pemigatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pemigatinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pemigatinib dose.pentamidineContraindicated (1)haloperidol and pentamidine both increase QTc interval. Contraindicated.pentazocineMonitor Closely (1)pentazocine and haloperidol both increase sedation. Use Caution/Monitor.pentobarbitalMonitor Closely (1)pentobarbital and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol, pentobarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.perhexilineMinor (1)haloperidol will increase the level or effect of perhexiline by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.perphenazineMonitor Closely (3)perphenazine will increase the level or effect of haloperidol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. haloperidol and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. haloperidol and perphenazine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)perphenazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.pexidartinibSerious - Use Alternative (1)haloperidol will increase the level or effect of pexidartinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pexidartinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pexidartinib dose.phendimetrazineMonitor Closely (1)haloperidol increases and phendimetrazine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.phenelzineMonitor Closely (1)phenelzine, 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).phenobarbitalMonitor Closely (2)phenobarbital will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. phenobarbital and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol, phenobarbital. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.phentermineMonitor Closely (1)haloperidol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.phenylephrineMonitor Closely (1)haloperidol increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.phenylephrine POMonitor Closely (1)haloperidol increases and phenylephrine PO decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. .phenytoinSerious - Use Alternative (1)phenytoin will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.pholcodineMonitor Closely (1)haloperidol and pholcodine both increase sedation. Use Caution/Monitor.pimozideContraindicated (1)haloperidol and pimozide both increase QTc interval. Contraindicated.Monitor Closely (2)haloperidol and pimozide both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. haloperidol and pimozide both increase sedation. Use Caution/Monitor.pirbuterolMonitor Closely (1)haloperidol increases and pirbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pitolisantSerious - Use Alternative (1)haloperidol and pitolisant both increase QTc interval. Avoid or Use Alternate Drug.posaconazoleMonitor Closely (1)haloperidol and posaconazole both increase QTc interval. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)posaconazole will increase the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.pralidoximeMonitor Closely (3)pralidoxime decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. pralidoxime decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. haloperidol increases effects of pralidoxime by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.pramipexoleSerious - Use Alternative (1)haloperidol decreases effects of pramipexole by pharmacodynamic antagonism. Contraindicated.primaquineMonitor Closely (1)primaquine and haloperidol both increase QTc interval. Use Caution/Monitor.primidoneMonitor Closely (2)primidone will decrease the level or effect of haloperidol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. primidone and haloperidol both increase sedation. Use Caution/Monitor.Minor (1)haloperidol, primidone. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hyperthermia if haloperidol admin. during barbiturate withdrawal.procainamideContraindicated (1)haloperidol and procainamide both increase QTc interval. Contraindicated.procarbazineMonitor Closely (1)procarbazine, 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).prochlorperazineMonitor Closely (2)haloperidol and prochlorperazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. haloperidol and prochlorperazine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)prochlorperazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of prochlorperazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.promazineSerious - Use Alternative (1)promazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of promazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.promethazineMonitor Closely (3)promethazine, 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 promethazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. promethazine and haloperidol both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)promethazine and haloperidol both increase QTc interval. Avoid or Use Alternate Drug.Minor (1)haloperidol will increase the level or effect of promethazine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.propafenoneMonitor Closely (2)haloperidol will increase the level or effect of propafenone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised. haloperidol and propafenone both increase QTc interval. Use Caution/Monitor.propanthelineMonitor Closely (3)propantheline decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. propantheline decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. haloperidol increases effects of propantheline by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.propofolMonitor Closely (1)propofol and haloperidol both increase sedation. Use Caution/Monitor.propranololMonitor Closely (1)haloperidol will increase the level or effect of propranolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. If concurrent use cannot be avoided, cautious dosing and telemetric monitoring is advised.