effects, including increased blood pressure and heart rate. Use Caution/Monitor. Closely monitor blood pressure with concomitant use of esketamine nasal with stimulants. .estazolamMonitor Closely (1)estazolam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.ethanolMonitor Closely (1)ethanol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.etherSerious - Use Alternative (1)ether increases toxicity of phentermine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.eucalyptusMinor (1)eucalyptus increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.fenfluramineMonitor Closely (2)phentermine and fenfluramine both decrease sedation. Use Caution/Monitor. fenfluramine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.fluoxetineSerious - Use Alternative (1)fluoxetine, phentermine. Either increases toxicity of the other by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of serotonin syndrome.fluphenazineMonitor Closely (2)fluphenazine, phentermine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. fluphenazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.flurazepamMonitor Closely (1)flurazepam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.fluvoxamineSerious - Use Alternative (1)fluvoxamine and phentermine both increase serotonin levels. Avoid or Use Alternate Drug.formoterolMonitor Closely (2)formoterol and phentermine both decrease sedation. Use Caution/Monitor. formoterol and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.green teaMonitor Closely (1)green tea, phentermine. Other (see comment). Use Caution/Monitor. Comment: Green tea may include caffeine. Caffeine is a CNS-stimulant and additive effects may be seen when coadministered with other CNS stimulants. Caffeine should be avoided or used cautiously.guaranaMinor (1)guarana increases effects of phentermine by pharmacodynamic synergism. Minor/Significance Unknown.haloperidolMonitor Closely (1)haloperidol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.hydralazineMonitor Closely (1)hydralazine, phentermine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.hydromorphoneMonitor Closely (1)hydromorphone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.hydroxyzineMonitor Closely (1)hydroxyzine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.iloperidoneMonitor Closely (1)iloperidone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.imipramineMonitor Closely (1)imipramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)imipramine, phentermine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.iobenguane I 123Contraindicated (1)phentermine decreases effects of iobenguane I 123 by receptor binding competition. Contraindicated. If clinically appropriate, discontinue drugs that compete for NE receptor sites for at least 5 half-lives; may cause false-negative imaging results.iobenguane I 131Serious - Use Alternative (1)phentermine 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.ioflupane I 123Monitor Closely (1)phentermine decreases effects of ioflupane I 123 by receptor binding competition. Use Caution/Monitor. Drugs that bind to dopamine transporter receptor with high affinity may interfere with the image following ioflupane I 123 administration.isocarboxazidContraindicated (1)isocarboxazid increases effects of phentermine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.isofluraneSerious - Use Alternative (1)isoflurane increases toxicity of phentermine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.isoproterenolMonitor Closely (2)isoproterenol and phentermine both decrease sedation. Use Caution/Monitor. isoproterenol and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.ketotifen, ophthalmicMonitor Closely (1)ketotifen, ophthalmic increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.levalbuterolMonitor Closely (2)levalbuterol and phentermine both decrease sedation. Use Caution/Monitor. levalbuterol and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.levomilnacipranSerious - Use Alternative (1)levomilnacipran and phentermine both increase serotonin levels. Avoid or Use Alternate Drug.levorphanolMonitor Closely (1)levorphanol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.linezolidContraindicated (1)linezolid increases effects of phentermine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.lisdexamfetamineMonitor Closely (2)lisdexamfetamine and phentermine both decrease sedation. Use Caution/Monitor. lisdexamfetamine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.lofepramineMonitor Closely (1)lofepramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)lofepramine, phentermine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.lofexidineMonitor Closely (1)lofexidine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.loprazolamMonitor Closely (1)loprazolam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.lorazepamMonitor Closely (1)lorazepam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.lormetazepamMonitor Closely (1)lormetazepam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.loxapineMonitor Closely (1)loxapine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.loxapine inhaledMonitor Closely (1)loxapine inhaled increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.maprotilineMonitor Closely (1)maprotiline increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)maprotiline, phentermine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.marijuanaMonitor Closely (1)marijuana increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.melatoninMonitor Closely (1)melatonin increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.meperidineMonitor Closely (1)meperidine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.meprobamateMonitor Closely (1)meprobamate increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.metaproterenolMonitor Closely (2)metaproterenol and phentermine both decrease sedation. Use Caution/Monitor. metaproterenol and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.metforminMonitor Closely (1)phentermine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.methadoneMonitor Closely (1)methadone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.methamphetamineMonitor Closely (2)methamphetamine and phentermine both decrease sedation. Use Caution/Monitor. methamphetamine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.methoxyfluraneSerious - Use Alternative (1)methoxyflurane increases toxicity of phentermine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.methyldopaMonitor Closely (1)methyldopa increases effects of phentermine by unknown mechanism. Use Caution/Monitor.methylenedioxymethamphetamineMonitor Closely (2)methylenedioxymethamphetamine and phentermine both decrease sedation. Use Caution/Monitor. methylenedioxymethamphetamine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.methylergonovineSerious - Use Alternative (1)methylergonovine, phentermine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.methylphenidateContraindicated (1)phentermine increases effects of methylphenidate by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.midazolamMonitor Closely (1)midazolam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.midodrineMonitor Closely (2)phentermine and midodrine both decrease sedation. Use Caution/Monitor. midodrine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.milnacipranSerious - Use Alternative (1)milnacipran, phentermine. Either increases toxicity of the other by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of serotonin syndrome.mirtazapineMonitor Closely (1)mirtazapine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.modafinilMonitor Closely (1)modafinil and phentermine both decrease sedation. Use Caution/Monitor.morphineMonitor Closely (1)morphine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.motherwortMonitor Closely (1)motherwort increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.moxonidineMonitor Closely (1)moxonidine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.nabiloneMonitor Closely (1)nabilone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.nalbuphineMonitor Closely (1)nalbuphine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.nefazodoneSerious - Use Alternative (1)nefazodone, phentermine. Either increases toxicity of the other by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of serotonin syndrome.norepinephrineMonitor Closely (2)norepinephrine and phentermine both decrease sedation. Use Caution/Monitor. norepinephrine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.nortriptylineMonitor Closely (1)nortriptyline increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)nortriptyline, phentermine. Other (see comment). Avoid or Use Alternate Drug. Comment: Tricyclic antidepressants increase or decrease effects of sympathomimetics, by blocking reuptake of NE, or blocking uptake of indirect sympathomimetics into the adrenergic neuron.olanzapineMonitor Closely (1)olanzapine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.opium tinctureMonitor Closely (1)opium tincture increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxazepamMonitor Closely (1)oxazepam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxycodoneMonitor Closely (1)oxycodone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxymorphoneMonitor Closely (1)oxymorphone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxytocinMonitor Closely (1)oxytocin increases effects of phentermine by pharmacodynamic synergism. Use Caution/Monitor.ozanimodSerious - Use Alternative (1)ozanimod increases toxicity of phentermine 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 (1)paliperidone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.papaveretumMonitor Closely (1)papaveretum increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.paroxetineSerious - Use Alternative (1)paroxetine, phentermine. Either increases toxicity of the other by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of serotonin syndrome.pentazocineMonitor Closely (1)pentazocine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pentobarbitalMonitor Closely (1)pentobarbital increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazineMonitor Closely (2)perphenazine, phentermine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only. perphenazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.phendimetrazineMonitor Closely (2)phentermine and phendimetrazine both decrease sedation. Use Caution/Monitor. phendimetrazine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.phenelzineContraindicated (1)phenelzine increases effects of phentermine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.phenobarbitalMonitor Closely (1)phenobarbital increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.phenylephrineMonitor Closely (2)phentermine and phenylephrine both decrease sedation. Use Caution/Monitor. phentermine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.phenylephrine POMonitor Closely (2)phentermine and phenylephrine PO both decrease sedation. Use Caution/Monitor. phentermine and phenylephrine PO both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.pholcodineMonitor Closely (1)pholcodine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pimozideMonitor Closely (1)pimozide increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pirbuterolMonitor Closely (2)pirbuterol and phentermine both decrease sedation. Use Caution/Monitor. pirbuterol and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.primidoneMonitor Closely (1)primidone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.procarbazineContraindicated (1)procarbazine increases effects of phentermine by pharmacodynamic synergism. Contraindicated. Risk of acute hypertensive episode.prochlorperazineMonitor Closely (2)prochlorperazine, phentermine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in