increase sedation. Use Caution/Monitor.ibutilideSerious - Use Alternative (1)mirtazapine and ibutilide both increase QTc interval. Avoid or Use Alternate Drug.idelalisibSerious - Use Alternative (1)idelalisib will increase the level or effect of mirtazapine 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 (2)iloperidone and mirtazapine both increase sedation. Use Caution/Monitor. iloperidone increases levels of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.Serious - Use Alternative (1)mirtazapine and iloperidone both increase QTc interval. Avoid or Use Alternate Drug.imipramineMonitor Closely (2)imipramine and mirtazapine both increase serotonin levels. Modify Therapy/Monitor Closely. imipramine and mirtazapine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)mirtazapine and imipramine both increase QTc interval. Avoid or Use Alternate Drug.indinavirMonitor Closely (1)indinavir will increase the level or effect of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.inotuzumabSerious - Use Alternative (1)mirtazapine and inotuzumab both increase QTc interval. Avoid or Use Alternate Drug.iobenguane I 123Contraindicated (1)mirtazapine 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)mirtazapine 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.isavuconazonium sulfateMonitor Closely (1)mirtazapine will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.isocarboxazidSerious - Use Alternative (1)isocarboxazid and mirtazapine both increase serotonin levels. Avoid or Use Alternate Drug.isofluraneSerious - Use Alternative (1)isoflurane and mirtazapine both increase QTc interval. Avoid or Use Alternate Drug.isoniazidMonitor Closely (1)isoniazid and mirtazapine both increase serotonin levels. Use Caution/Monitor.Serious - Use Alternative (1)isoniazid will increase the level or effect of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.isoproterenolMonitor Closely (1)mirtazapine increases and isoproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.istradefyllineMonitor Closely (1)istradefylline will increase the level or effect of mirtazapine 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 mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. itraconazole and mirtazapine both increase QTc interval. Use Caution/Monitor.ivosidenibSerious - Use Alternative (2)ivosidenib will decrease the level or effect of mirtazapine 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. mirtazapine and ivosidenib both decrease QTc interval. Avoid or Use Alternate Drug.ketamineMonitor Closely (1)ketamine and mirtazapine both increase sedation. Use Caution/Monitor.ketoconazoleMonitor Closely (1)ketoconazole will increase the level or effect of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce mirtazapine dose if coadministration of strong CYP3A4 inhibitor is necessary. Once CYP3A4 inhibitor is discontinued, consider increasing mirtazapine dose.ketotifen, ophthalmicMonitor Closely (1)ketotifen, ophthalmic and mirtazapine both increase sedation. Use Caution/Monitor.L-tryptophanMonitor Closely (1)L-tryptophan and mirtazapine both increase serotonin levels. Use Caution/Monitor.lapatinibMonitor Closely (1)mirtazapine and lapatinib both increase QTc interval. Use Caution/Monitor.larotrectinibMinor (1)larotrectinib will increase the level or effect of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.lasmiditanMonitor Closely (1)lasmiditan, mirtazapine. 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.lefamulinContraindicated (1)lefamulin will increase the level or effect of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Lefamulin is contraindicated with CYP3A substrates know to prolong the QT interval.Serious - Use Alternative (1)mirtazapine and lefamulin both increase QTc interval. Avoid or Use Alternate Drug.lemborexantMonitor Closely (2)mirtazapine will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Lower nightly dose of lemborexant recommended if coadministered with weak CYP3A4 inhibitors. See drug monograph for specific dosage modification. lemborexant, mirtazapine. 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 mirtazapine 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.lenvatinibSerious - Use Alternative (1)mirtazapine and lenvatinib both increase QTc interval. Avoid or Use Alternate Drug.letermovirMonitor Closely (1)letermovir increases levels of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.leuprolideMonitor Closely (1)mirtazapine and leuprolide both increase QTc interval. Use Caution/Monitor.levalbuterolMonitor Closely (1)mirtazapine increases and levalbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.levofloxacinMonitor Closely (1)mirtazapine and levofloxacin both increase QTc interval. Use Caution/Monitor.levoketoconazoleMonitor Closely (1)levoketoconazole will increase the level or effect of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce mirtazapine dose if coadministration of strong CYP3A4 inhibitor is necessary. Once CYP3A4 inhibitor is discontinued, consider increasing mirtazapine dose.levomilnacipranMonitor Closely (1)levomilnacipran and mirtazapine both increase serotonin levels. Modify Therapy/Monitor Closely.levorphanolMonitor Closely (1)levorphanol and mirtazapine both increase sedation. Use Caution/Monitor.linezolidSerious - Use Alternative (1)linezolid and mirtazapine 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)mirtazapine increases and lisdexamfetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.lithiumMonitor Closely (1)lithium and mirtazapine both increase serotonin levels. Use Caution/Monitor.Serious - Use Alternative (1)lithium and mirtazapine both increase QTc interval. Avoid or Use Alternate Drug.lofepramineMonitor Closely (2)lofepramine and mirtazapine both increase serotonin levels. Modify Therapy/Monitor Closely. lofepramine and mirtazapine both increase sedation. Use Caution/Monitor.lofexidineMonitor Closely (2)mirtazapine and lofexidine both increase QTc interval. Use Caution/Monitor. lofexidine and mirtazapine both increase sedation. Use Caution/Monitor.lomitapideMonitor Closely (1)mirtazapine increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lomitapide dose should not exceed 30 mg/day.lonafarnibSerious - Use Alternative (1)mirtazapine will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of lonafarnib (a sensitive CYP3A substrate) with weak CYP3A inhibitors is unavoidable, reduce to, or continue lonafarnib at starting dose. Closely monitor for arrhythmias and events (eg, syncope, heart palpitations) since lonafarnib effect on QT interval is unknown.loperamideMonitor Closely (1)mirtazapine and loperamide both increase QTc interval. Use Caution/Monitor.lopinavirMonitor Closely (1)lopinavir increases levels of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.Serious - Use Alternative (1)mirtazapine and lopinavir both increase QTc interval. Avoid or Use Alternate Drug.loprazolamMonitor Closely (1)loprazolam and mirtazapine both increase sedation. Use Caution/Monitor.lorazepamMonitor Closely (1)lorazepam and mirtazapine both increase sedation. Use Caution/Monitor.lorcaserinMonitor Closely (1)lorcaserin will increase the level or effect of mirtazapine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)mirtazapine and lorcaserin both increase serotonin levels. Avoid or Use Alternate Drug.lorlatinibMonitor Closely (1)lorlatinib will decrease the level or effect of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.lormetazepamMonitor Closely (1)lormetazepam and mirtazapine both increase sedation. Use Caution/Monitor.loxapineMonitor Closely (1)loxapine and mirtazapine both increase sedation. Use Caution/Monitor.loxapine inhaledMonitor Closely (1)loxapine inhaled and mirtazapine both increase sedation. Use Caution/Monitor.lsdMonitor Closely (1)lsd and mirtazapine both increase serotonin levels. Use Caution/Monitor.lurasidoneMonitor Closely (1)lurasidone increases effects of mirtazapine by Other (see comment). Use Caution/Monitor. Comment: Potential for additive CNS effects .macimorelinSerious - Use Alternative (1)mirtazapine and macimorelin both increase QTc interval. Avoid or Use Alternate Drug.maprotilineMonitor Closely (2)maprotiline and mirtazapine both increase serotonin levels. Modify Therapy/Monitor Closely. maprotiline and mirtazapine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)mirtazapine and maprotiline both increase QTc interval. Avoid or Use Alternate Drug.maravirocMonitor Closely (1)maraviroc, mirtazapine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of orthostatic hypotension.marijuanaMonitor Closely (1)marijuana and mirtazapine both increase sedation. Use Caution/Monitor.mefloquineSerious - Use Alternative (1)mefloquine increases toxicity of mirtazapine by QTc interval. Avoid or Use Alternate Drug. Mefloquine may enhance the QTc prolonging effect of high risk QTc prolonging agents.melatoninMonitor Closely (1)melatonin and mirtazapine both increase sedation. Use Caution/Monitor.meperidineMonitor Closely (2)meperidine and mirtazapine both increase serotonin levels. Modify Therapy/Monitor Closely. meperidine and mirtazapine both increase sedation. Use Caution/Monitor.meprobamateMonitor Closely (1)meprobamate and mirtazapine both increase sedation. Use Caution/Monitor.metaproterenolMonitor Closely (1)mirtazapine increases and metaproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.metaxaloneMonitor Closely (1)metaxalone and mirtazapine both increase sedation. Use Caution/Monitor.methadoneMonitor Closely (1)methadone and mirtazapine both increase sedation. Use Caution/Monitor.Serious - Use Alternative (1)mirtazapine and methadone both increase QTc interval. Avoid or Use Alternate Drug.methamphetamineMonitor Closely (1)mirtazapine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.methocarbamolMonitor Closely (1)methocarbamol and mirtazapine both increase sedation. Use Caution/Monitor.methylene blueSerious - Use Alternative (1)methylene blue and mirtazapine both increase serotonin levels. Avoid or Use Alternate Drug. Methylene blue may increase serotonin as a result of MAO-A inhibition. If methylene blue must be administered, discontinue serotonergic drug immediately and monitor for CNS toxicity. Serotonergic therapy may be resumed 24 hours after last methylene blue dose or after 2 weeks of monitoring, whichever comes first.methylenedioxymethamphetamineMonitor Closely (1)mirtazapine increases and methylenedioxymethamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.metoclopramide intranasalSerious - Use Alternative (1)mirtazapine, metoclopramide intranasal. Either increases effects of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Avoid use of metoclopramide intranasal or interacting drug, depending on importance of drug to patient.midazolamMonitor Closely (1)midazolam and mirtazapine both increase sedation. Use Caution/Monitor.midazolam intranasalMonitor Closely (2)mirtazapine will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of mild CYP3A4 inhibitors with midazolam intranasal may cause higher midazolam systemic exposure, which may prolong sedation. midazolam intranasal, mirtazapine. 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.midodrineMonitor Closely (1)mirtazapine increases and midodrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.midostaurinSerious - Use Alternative (1)mirtazapine and midostaurin both increase QTc interval. Avoid or Use Alternate Drug.mifepristoneMonitor Closely (1)mifepristone will increase the level or effect of mirtazapine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)mirtazapine and mifepristone both increase QTc interval. Avoid or Use Alternate Drug.milnacipranMonitor Closely (1)milnacipran and mirtazapine both increase serotonin levels. Modify Therapy/Monitor Closely.mipomersenMonitor Closely (1)mipomersen, mirtazapine. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Both drugs have potential to increase hepatic enzymes; monitor LFTs.mirabegronMonitor Closely (1)mirabegron will increase the level or effect of mirtazapine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.mitotaneMonitor Closely (1)mitotane decreases levels of mirtazapine 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.mobocertinibSerious - Use Alternative (1)mirtazapine and mobocertinib both increase QTc interval. Avoid or Use Alternate Drug.modafinilMonitor Closely (1)mirtazapine increases and modafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.morphineMonitor Closely (2)morphine and mirtazapine both increase sedation. Use Caution/Monitor. mirtazapine and morphine both increase serotonin levels. Use Caution/Monitor.motherwortMonitor Closely (1)mirtazapine and motherwort both increase sedation. Use Caution/Monitor.moxifloxacinSerious - Use Alternative (1)mirtazapine and moxifloxacin both increase QTc interval. Avoid or Use Alternate Drug.moxonidineMonitor Closely (1)mirtazapine and moxonidine both increase sedation. Use Caution/Monitor.nabiloneMonitor Closely (1)mirtazapine and nabilone both increase sedation. Use Caution/Monitor.nalbuphineMonitor Closely (1)nalbuphine and mirtazapine both increase sedation. Use Caution/Monitor.naratriptanMonitor Closely (1)naratriptan and mirtazapine both increase serotonin levels. Use Caution/Monitor.nefazodoneMonitor Closely (1)nefazodone and mirtazapine both increase serotonin levels. Modify Therapy/Monitor