effect of olanzapine 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 (3)oxaliplatin and olanzapine both increase QTc interval. Avoid or Use Alternate Drug. Limited data, including some case reports, suggest that olanzapine may be associated with a significant prolongation of the QTc interval in rare instances olanzapine and oxaliplatin both increase QTc interval. Avoid or Use Alternate Drug. oxaliplatin and fluoxetine both increase QTc interval. Avoid or Use Alternate Drug.oxaprozinMonitor Closely (1)fluoxetine, oxaprozin. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.oxazepamMonitor Closely (1)oxazepam and olanzapine both increase sedation. Use Caution/Monitor.oxybutyninMonitor Closely (3)oxybutynin decreases levels of olanzapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. oxybutynin decreases levels of olanzapine by pharmacodynamic antagonism. Use Caution/Monitor. olanzapine increases effects of oxybutynin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxybutynin topicalMonitor Closely (3)oxybutynin topical decreases levels of olanzapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. oxybutynin topical decreases levels of olanzapine by pharmacodynamic antagonism. Use Caution/Monitor. olanzapine 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 olanzapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. oxybutynin transdermal decreases levels of olanzapine by pharmacodynamic antagonism. Use Caution/Monitor. olanzapine increases effects of oxybutynin transdermal by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxycodoneMonitor Closely (1)oxycodone and olanzapine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)oxycodone will increase the level or effect of fluoxetine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Opioids may enhance the serotonergic effects of SSRIs and increase risk for serotonergic syndromeoxymorphoneMonitor Closely (1)oxymorphone and olanzapine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)fluoxetine will increase the level or effect of oxymorphone by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.ozanimodMonitor Closely (2)ozanimod and fluoxetine 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. ozanimod and olanzapine 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.Serious - Use Alternative (1)ozanimod increases toxicity of fluoxetine by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Avoid or Use Alternate Drug. Because the active metabolite of ozanimod inhibits MAO-B in vitro, there is a potential for serious adverse reactions, including hypertensive crisis. Therefore, coadministration of ozanimod with drugs that can increase norepinephrine or serotonin is not recommended. Monitor for hypertension with concomitant use.paliperidoneMonitor Closely (3)olanzapine and paliperidone both increase sedation. Use Caution/Monitor. fluoxetine and paliperidone both increase QTc interval. Use Caution/Monitor. olanzapine and paliperidone both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.Serious - Use Alternative (1)olanzapine and paliperidone both increase QTc interval. Avoid or Use Alternate Drug.palonosetronSerious - Use Alternative (1)palonosetron, fluoxetine. Either increases toxicity of the other by serotonin levels. Avoid or Use Alternate Drug.panax ginsengMinor (1)panax ginseng increases effects of fluoxetine by pharmacodynamic synergism. Minor/Significance Unknown.pancuroniumMonitor Closely (3)pancuronium decreases levels of olanzapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. pancuronium decreases levels of olanzapine by pharmacodynamic antagonism. Use Caution/Monitor. olanzapine increases effects of pancuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.panobinostatSerious - Use Alternative (2)fluoxetine 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. olanzapine and panobinostat both increase QTc interval. Avoid or Use Alternate Drug.papaveretumMonitor Closely (1)papaveretum and olanzapine both increase sedation. Use Caution/Monitor.papaverineMonitor Closely (1)olanzapine and papaverine both increase sedation. Use Caution/Monitor.parecoxibMonitor Closely (2)fluoxetine will increase the level or effect of parecoxib by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. fluoxetine, parecoxib. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.Minor (1)parecoxib will increase the level or effect of fluoxetine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.paroxetineMonitor Closely (2)paroxetine, olanzapine. 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). fluoxetine and paroxetine both increase QTc interval. Use Caution/Monitor.Serious - Use Alternative (3)fluoxetine will increase the level or effect of paroxetine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. olanzapine and paroxetine both increase QTc interval. Avoid or Use Alternate Drug. fluoxetine and paroxetine both increase serotonin levels. Avoid or Use Alternate Drug.pasireotideMonitor Closely (2)olanzapine and pasireotide both increase QTc interval. Modify Therapy/Monitor Closely. fluoxetine and pasireotide both increase QTc interval. Modify Therapy/Monitor Closely.pazopanibMinor (1)fluoxetine and pazopanib both increase QTc interval. Minor/Significance Unknown.Serious - Use Alternative (1)olanzapine and pazopanib both increase QTc interval. Avoid or Use Alternate Drug.pefloxacinSerious - Use Alternative (1)pefloxacin will increase the level or effect of olanzapine by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug.peginterferon alfa 2aMonitor Closely (1)peginterferon alfa 2a will increase the level or effect of olanzapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.peginterferon alfa 2bMonitor Closely (1)peginterferon alfa 2b, fluoxetine. 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.pentamidineSerious - Use Alternative (2)fluoxetine and pentamidine both increase QTc interval. Avoid or Use Alternate Drug. olanzapine and pentamidine both increase QTc interval. Avoid or Use Alternate Drug.pentazocineMonitor Closely (2)pentazocine and olanzapine both increase sedation. Use Caution/Monitor. fluoxetine and pentazocine both increase serotonin levels. Modify Therapy/Monitor Closely.pentobarbitalMonitor Closely (2)pentobarbital will decrease the level or effect of olanzapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. pentobarbital and olanzapine both increase sedation. Use Caution/Monitor.pentoxifyllineMonitor Closely (1)pentoxifylline increases toxicity of fluoxetine by anticoagulation. Use Caution/Monitor. May increase bleeding.perhexilineMonitor Closely (1)fluoxetine will increase the level or effect of perhexiline by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.perphenazineMonitor Closely (3)olanzapine and perphenazine both increase sedation. Use Caution/Monitor. olanzapine and perphenazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. olanzapine and perphenazine both increase QTc interval. Use Caution/Monitor.Serious - Use Alternative (3)perphenazine and fluoxetine both increase QTc interval. Avoid or Use Alternate Drug. perphenazine will increase the level or effect of fluoxetine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. fluoxetine will increase the level or effect of perphenazine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.phendimetrazineMonitor Closely (1)olanzapine increases and phendimetrazine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.phenelzineContraindicated (1)phenelzine and fluoxetine both increase serotonin levels. Contraindicated.Monitor Closely (1)phenelzine, olanzapine. 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 olanzapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. phenobarbital and olanzapine both increase sedation. Use Caution/Monitor.phentermineMonitor Closely (1)olanzapine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)fluoxetine, phentermine. Either increases toxicity of the other by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of serotonin syndrome.phenylephrineMonitor Closely (1)olanzapine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.phenylephrine POMonitor Closely (1)olanzapine increases and phenylephrine PO decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. .phenytoinMonitor Closely (1)fluoxetine will increase the level or effect of phenytoin by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor.pholcodineMonitor Closely (1)olanzapine and pholcodine both increase sedation. Use Caution/Monitor.pimavanserinSerious - Use Alternative (1)olanzapine and pimavanserin both increase QTc interval. Avoid or Use Alternate Drug.pimozideContraindicated (2)fluoxetine and pimozide both increase QTc interval. Contraindicated. fluoxetine increases levels of pimozide by decreasing metabolism. Contraindicated. Risk of QT interval prolongation.Monitor Closely (2)olanzapine and pimozide both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor. olanzapine and pimozide both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)olanzapine and pimozide both increase QTc interval. Contraindicated.pioglitazoneMonitor Closely (1)olanzapine, pioglitazone. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.pipemidic acidMonitor Closely (1)pipemidic acid will increase the level or effect of olanzapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.pirbuterolMonitor Closely (2)olanzapine increases and pirbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. fluoxetine and pirbuterol both increase QTc interval. Modify Therapy/Monitor Closely. Fluoxetine prolongs the QT interval; the prescribing information for fluoxetine recommends avoiding concurrent use of other drugs that may prolong the QT interval; risk may be increased with higher doses and/or when associated with hypokalemia; drugs that prolong the QTc interval may potentiate the effects of beta2 agonists on the cardiovascular systempirfenidoneSerious - Use Alternative (1)fluoxetine will increase the level or effect of pirfenidone by affecting hepatic enzyme CYP1A2 metabolism. Avoid or Use Alternate Drug. Avoid; coadministration of pirfenidone and moderate CYP1A2 inhibitors result in moderately increased exposure to pirfenidone; if unable to avoid, decrease dose of moderate CYP1A2 inhibitorpiroxicamMonitor Closely (2)fluoxetine will increase the level or effect of piroxicam by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. fluoxetine, piroxicam. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.pitolisantMonitor Closely (1)fluoxetine will increase the level or effect of pitolisant by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If coadministered with strong CYP2D6 inhibitors, initiate pitolisant at 8.9 mg/day and increase after 7 days to maximum of 17.8 mg/day. For patients currently taking pitolisant, reduce pitolisant dose by half upon initiating strong CYP2D6 inhibitors.Serious - Use Alternative (2)fluoxetine and pitolisant both increase QTc interval. Avoid or Use Alternate Drug. olanzapine and pitolisant both increase QTc interval. Avoid or Use Alternate Drug.pleurisy rootMinor (1)pleurisy root decreases effects of fluoxetine by unspecified interaction mechanism. Minor/Significance Unknown. Theoretical interaction.ponesimodSerious - Use Alternative (1)olanzapine and ponesimod both increase QTc interval. Avoid or Use Alternate Drug.posaconazoleMonitor Closely (2)olanzapine and posaconazole both increase QTc interval. Use Caution/Monitor. fluoxetine and posaconazole both increase QTc interval. Use Caution/Monitor.pralidoximeMonitor Closely (3)pralidoxime decreases levels of olanzapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. pralidoxime decreases levels of olanzapine by pharmacodynamic antagonism. Use Caution/Monitor. olanzapine increases effects of pralidoxime by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.pramipexoleSerious - Use Alternative (1)olanzapine decreases effects of pramipexole by pharmacodynamic antagonism. Contraindicated.pramlintideMonitor Closely (1)olanzapine, pramlintide. Other (see comment). Use Caution/Monitor. Comment: Atypical antipsychotics have been associated with hyperglycemia that may alter blood glucose control; monitor glucose levels closely.pregabalinMonitor Closely (1)pregabalin, fluoxetine. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration of CNS depressants can result in serious, life-threatening, and fatal respiratory depression. Use lowest dose possible and monitor for respiratory depression and sedation.primaquineMonitor Closely (2)primaquine and fluoxetine both increase QTc interval. Use Caution/Monitor. olanzapine and primaquine both increase QTc interval. Use Caution/Monitor.primidoneMonitor Closely (2)primidone will decrease the level or effect of olanzapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. primidone and olanzapine both increase sedation. Use Caution/Monitor.procainamideSerious - Use Alternative (2)fluoxetine and procainamide both increase QTc interval. Avoid or Use Alternate Drug. olanzapine and procainamide both increase QTc interval. Avoid or Use Alternate Drug.procarbazineContraindicated (1)procarbazine and fluoxetine both increase serotonin levels. Contraindicated. Combinations is contraindicated within 5 weeks of MAOI use.Monitor Closely (1)procarbazine, olanzapine. unspecified interaction mechanism. Use Caution/Monitor. Serotonin modulators may enhance dopamine blockade, possibly