Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.fenfluramineMonitor Closely (2)fenfluramine, venlafaxine. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Coadministration with drugs that increase serotoninergic effects may increase the risk of serotonin syndrome. venlafaxine and fenfluramine both increase serotonin levels. Modify Therapy/Monitor Closely.fenoprofenMonitor Closely (1)venlafaxine, fenoprofen. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.fentanylSerious - Use Alternative (1)venlafaxine and fentanyl both increase serotonin levels. Avoid or Use Alternate Drug. May cause serotonin syndromefesoterodineMinor (1)venlafaxine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.fexinidazoleSerious - Use Alternative (1)fexinidazole will increase the level or effect of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.fingolimodMonitor Closely (1)fingolimod and venlafaxine both decrease QTc interval. Use Caution/Monitor.fish oil triglyceridesMonitor Closely (1)fish oil triglycerides will increase the level or effect of venlafaxine by anticoagulation. Use Caution/Monitor. Prolonged bleeding reported in patients taking antiplatelet agents or anticoagulants and oral omega-3 fatty acids. Periodically monitor bleeding time in patients receiving fish oil triglycerides and concomitant antiplatelet agents or anticoagulants.flecainideMonitor Closely (2)venlafaxine will increase the level or effect of flecainide by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. flecainide and venlafaxine both increase QTc interval. Use Caution/Monitor.fluconazoleMonitor Closely (1)fluconazole and venlafaxine both increase QTc interval. Modify Therapy/Monitor Closely.fluoxetineMonitor Closely (1)fluoxetine and venlafaxine both increase QTc interval. Use Caution/Monitor.Serious - Use Alternative (1)fluoxetine and venlafaxine both increase serotonin levels. Avoid or Use Alternate Drug.Minor (1)venlafaxine will increase the level or effect of fluoxetine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.fluphenazineMonitor Closely (2)venlafaxine, fluphenazine. 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). venlafaxine will increase the level or effect of fluphenazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)fluphenazine and venlafaxine both increase QTc interval. Avoid or Use Alternate Drug.flurbiprofenMonitor Closely (1)venlafaxine, flurbiprofen. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.fluvoxamineMonitor Closely (1)fluvoxamine and venlafaxine both increase QTc interval. Use Caution/Monitor.Serious - Use Alternative (1)fluvoxamine and venlafaxine both increase serotonin levels. Avoid or Use Alternate Drug.formoterolMonitor Closely (1)formoterol and venlafaxine both increase QTc interval. Modify Therapy/Monitor Closely.foscarnetMonitor Closely (1)foscarnet and venlafaxine both increase QTc interval. Use Caution/Monitor.frovatriptanMonitor Closely (1)frovatriptan and venlafaxine both increase serotonin levels. Modify Therapy/Monitor Closely.Minor (1)venlafaxine, frovatriptan. Mechanism: unknown. Minor/Significance Unknown. Risk of weakness, dyspnea, chest pain.furosemideMinor (1)furosemide, venlafaxine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Possible additive hyponatremia.gabapentinMonitor Closely (1)gabapentin, venlafaxine. 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.gabapentin enacarbilMonitor Closely (1)gabapentin enacarbil, venlafaxine. 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.galantamineMinor (1)venlafaxine will increase the level or effect of galantamine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.ganaxoloneMonitor Closely (1)venlafaxine and ganaxolone both increase sedation. Use Caution/Monitor.gemifloxacinMonitor Closely (1)gemifloxacin and venlafaxine both decrease QTc interval. Use Caution/Monitor.gilteritinibMonitor Closely (1)gilteritinib and venlafaxine both decrease QTc interval. Use Caution/Monitor.givosiranSerious - Use Alternative (1)givosiran will increase the level or effect of venlafaxine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling.granisetronMonitor Closely (1)granisetron and venlafaxine both decrease QTc interval. Use Caution/Monitor.Serious - Use Alternative (1)granisetron, venlafaxine. Either increases toxicity of the other by serotonin levels. Avoid or Use Alternate Drug.green teaMonitor Closely (1)green tea, venlafaxine. Other (see comment). Use Caution/Monitor. Comment: Combination may increase risk of bleeding.haloperidolMonitor 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.hydrocodoneMonitor Closely (2)hydrocodone, venlafaxine. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Coadministration of drugs that affect the serotonergic neurotransmitter system may result in serotonin syndrome. If concomitant use is warranted, carefully observe the patient, particularly during treatment initiation and dose adjustment. venlafaxine will increase the level or effect of hydrocodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Hydromorphone (<3% of the circulating parent hydrocodone) is mainly formed by CYP2D6 mediated O-demethylation of hydrocodone. Hydromorphone may contribute to the total analgesic effect of hydrocodone.hydromorphoneMonitor Closely (1)venlafaxine will increase the level or effect of hydromorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.hydroxyzineMonitor Closely (1)hydroxyzine and venlafaxine both decrease QTc interval. Use Caution/Monitor.ibrutinibMonitor Closely (1)ibrutinib will increase the level or effect of venlafaxine by anticoagulation. Use Caution/Monitor. Ibrutinib may increase the risk of hemorrhage in patients receiving antiplatelet or anticoagulant therapies and monitor for signs of bleeding. ibuprofenMonitor Closely (1)venlafaxine, ibuprofen. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.ibuprofen IVMonitor Closely (1)venlafaxine, ibuprofen IV. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.ibutilideSerious - Use Alternative (1)ibutilide and venlafaxine both increase QTc interval. Avoid or Use Alternate Drug.idelalisibSerious - Use Alternative (1)idelalisib will increase the level or effect of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substratesiloperidoneMonitor Closely (4)venlafaxine, iloperidone. 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). iloperidone increases levels of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4. venlafaxine will increase the level or effect of iloperidone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. iloperidone and venlafaxine both increase QTc interval. Use Caution/Monitor.imipramineMonitor Closely (2)venlafaxine will increase the level or effect of imipramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. imipramine and venlafaxine both increase QTc interval. Modify Therapy/Monitor Closely.Serious - Use Alternative (1)venlafaxine and imipramine both increase serotonin levels. Avoid or Use Alternate Drug.indapamideSerious - Use Alternative (1)indapamide and venlafaxine both increase QTc interval. Avoid or Use Alternate Drug.indinavirMonitor Closely (1)indinavir will increase the level or effect of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.indomethacinMonitor Closely (1)venlafaxine, indomethacin. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.iobenguane I 123Contraindicated (1)venlafaxine decreases effects of iobenguane I 123 by pharmacodynamic antagonism. Contraindicated. If clinically appropriate, discontinue drugs that decrease uptake of NE for at least 5 half-lives; may cause false-negative imaging results.iobenguane I 131Serious - Use Alternative (1)venlafaxine will decrease the level or effect of iobenguane I 131 by Other (see comment). Avoid or Use Alternate Drug. Based on the mechanism of action of iobenguane, drugs that reduce catecholamine uptake or that deplete catecholamine stores may interfere with iobenguane uptake into cells, and thus, reduce iobenguane efficacy. Discontinue interfering drugs for at least 5 half-lives before administration of either the dosimetry or an iobenguane dose. Do not administer these drugs until at least 7 days after each iobenguane dose.isocarboxazidContraindicated (1)isocarboxazid and venlafaxine both increase serotonin levels. Contraindicated.isofluraneSerious - Use Alternative (1)isoflurane and venlafaxine both decrease QTc interval. Avoid or Use Alternate Drug.isoniazidMonitor Closely (1)venlafaxine and isoniazid both increase serotonin levels. Modify Therapy/Monitor Closely.istradefyllineMonitor Closely (1)istradefylline will increase the level or effect of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.itraconazoleMonitor Closely (2)itraconazole will increase the level or effect of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. itraconazole and venlafaxine both increase QTc interval. Modify Therapy/Monitor Closely.ivosidenibSerious - Use Alternative (1)ivosidenib will decrease the level or effect of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternative therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.ketoconazoleMonitor Closely (2)ketoconazole and venlafaxine both increase QTc interval. Use Caution/Monitor. ketoconazole will increase the level or effect of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ketoprofenMonitor Closely (1)venlafaxine, ketoprofen. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.ketorolacMonitor Closely (1)venlafaxine, ketorolac. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.ketorolac intranasalMonitor Closely (1)venlafaxine, ketorolac intranasal. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of upper GI bleeding. SSRIs inhib. serotonin uptake by platelets.L-tryptophanMonitor Closely (1)venlafaxine and L-tryptophan both increase serotonin levels. Modify Therapy/Monitor Closely.lapatinibMonitor Closely (1)lapatinib and venlafaxine both increase QTc interval. Use Caution/Monitor.larotrectinibMinor (1)larotrectinib will increase the level or effect of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.lasmiditanMonitor Closely (2)lasmiditan, venlafaxine. 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. venlafaxine increases effects of lasmiditan by serotonin levels. Use Caution/Monitor. Coadministration may increase risk of serotonin syndrome.lemborexantMonitor Closely (1)lemborexant, venlafaxine. 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.lenacapavirMonitor Closely (1)lenacapavir will increase the level or effect of venlafaxine 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.levofloxacinMonitor Closely (1)levofloxacin and venlafaxine both increase QTc interval. Use Caution/Monitor.levoketoconazoleMonitor Closely (2)levoketoconazole will increase the level or effect of venlafaxine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. levoketoconazole and venlafaxine both increase QTc interval. Use Caution/Monitor.levomilnacipranSerious - Use Alternative (1)levomilnacipran and venlafaxine both increase serotonin levels. Avoid or Use Alternate Drug.levorphanolSerious - Use Alternative (1)venlafaxine and levorphanol both increase serotonin levels. Avoid or Use Alternate Drug. May cause serotonin syndromelinezolidSerious - Use Alternative (1)linezolid and venlafaxine both increase serotonin levels. Avoid or Use Alternate Drug. Linezolid may increase serotonin as a result of MAO-A inhibition. If linezolid must be administered, discontinue serotonergic drug immediately and monitor for CNS toxicity. Serotonergic therapy may be resumed 24 hours after last linezolid dose or after 2 weeks of monitoring, whichever comes first.lisdexamfetamineMonitor Closely (1)venlafaxine, lisdexamfetamine. Either increases effects of the other by serotonin levels. Use Caution/Monitor. Initiate with lower doses and monitor for signs and symptoms of serotonin syndrome, particularly during initiation or dosage increase. If serotonin syndrome occurs, discontinue along with concomitant serotonergic drug(s).lithiumMonitor Closely (2)venlafaxine and lithium both increase serotonin levels. Modify Therapy/Monitor Closely. lithium and venlafaxine both decrease QTc interval. Use Caution/Monitor.Minor (1)venlafaxine, lithium. Mechanism: unknown. Minor/Significance Unknown. Risk of neurotoxicity.lofepramineMonitor Closely (2)venlafaxine will increase the level or effect of lofepramine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. lofepramine and