decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dexmethylphenidatedexmethylphenidate and phentermine both decrease sedation. Use Caution/Monitor.dexmethylphenidate and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.dextroamphetaminedextroamphetamine and phentermine both decrease sedation. Use Caution/Monitor.dextroamphetamine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.dextromoramidedextromoramide increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.diamorphinediamorphine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dichlorphenamidedichlorphenamide and phentermine both decrease serum potassium. Use Caution/Monitor.diethylpropionphentermine and diethylpropion both decrease sedation. Use Caution/Monitor.diethylpropion and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.difenoxin hcldifenoxin hcl increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.diltiazemphentermine will decrease the level or effect of diltiazem by pharmacodynamic antagonism. Use Caution/Monitor. Amphetamines may diminish antihypertensive effects of diltiazem. Monitor BP.dimenhydrinatedimenhydrinate increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.diphenhydraminediphenhydramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.diphenoxylate hcldiphenoxylate hcl increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dipipanonedipipanone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dobutaminedobutamine and phentermine both decrease sedation. Use Caution/Monitor.dobutamine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.dopaminephentermine and dopamine both decrease sedation. Use Caution/Monitor.dopamine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.dopexaminedopexamine and phentermine both decrease sedation. Use Caution/Monitor.dopexamine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.doxepindoxepin increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.droperidoldroperidol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.droxidopaphentermine and droxidopa both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. May increase risk for supine hypertensionephedrineephedrine and phentermine both decrease sedation. Use Caution/Monitor.ephedrine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.ephedrine, phentermine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor.epinephrineepinephrine and phentermine both decrease sedation. Use Caution/Monitor.epinephrine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.epinephrine inhaledphentermine, epinephrine inhaled. Either increases effects of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.epinephrine racemicepinephrine racemic and phentermine both decrease sedation. Use Caution/Monitor.epinephrine racemic and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.esketamine intranasalesketamine intranasal, phentermine. Either increases toxicity of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Closely monitor blood pressure with concomitant use of esketamine nasal with stimulants. .estazolamestazolam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.ethanolethanol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.fenfluraminephentermine 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.fluphenazinefluphenazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.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.flurazepamflurazepam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.formoterolformoterol 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 teagreen 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.haloperidolhaloperidol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.hydralazinehydralazine, phentermine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Sympathomimetics can antagonize the activity of some antihypertensive agents.hydromorphonehydromorphone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.hydroxyzinehydroxyzine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.iloperidoneiloperidone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.imipramineimipramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.ioflupane I 123phentermine 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.isoproterenolisoproterenol 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, ophthalmicketotifen, ophthalmic increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.levalbuterollevalbuterol 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.levorphanollevorphanol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.lisdexamfetaminelisdexamfetamine 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.lofepraminelofepramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.lofexidinelofexidine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.loprazolamloprazolam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.lorazepamlorazepam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.lormetazepamlormetazepam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.loxapineloxapine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.loxapine inhaledloxapine inhaled increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.maprotilinemaprotiline increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.marijuanamarijuana increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.melatoninmelatonin increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.meperidinemeperidine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.meprobamatemeprobamate increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.metaproterenolmetaproterenol 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.metforminphentermine 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.methadonemethadone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.methamphetaminemethamphetamine 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.methyldopamethyldopa increases effects of phentermine by unknown mechanism. Use Caution/Monitor.methylenedioxymethamphetaminemethylenedioxymethamphetamine 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.midazolammidazolam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.midodrinephentermine 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.mirtazapinemirtazapine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.modafinilmodafinil and phentermine both decrease sedation. Use Caution/Monitor.morphinemorphine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.motherwortmotherwort increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.moxonidinemoxonidine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.nabilonenabilone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.nalbuphinenalbuphine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.norepinephrinenorepinephrine 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.nortriptylinenortriptyline increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.olanzapineolanzapine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.opium tinctureopium tincture increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxazepamoxazepam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxycodoneoxycodone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxymorphoneoxymorphone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxytocinoxytocin increases effects of phentermine by pharmacodynamic synergism. Use Caution/Monitor.paliperidonepaliperidone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.papaveretumpapaveretum increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pentazocinepentazocine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pentobarbitalpentobarbital increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazineperphenazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.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.phendimetrazinephentermine 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.phenobarbitalphenobarbital increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.phenylephrinephentermine 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 POphentermine 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.pholcodinepholcodine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pimozidepimozide increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pirbuterolpirbuterol 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.primidoneprimidone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.prochlorperazineprochlorperazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.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 certain predisposed pts. only.promazinepromazine, 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.promethazinepromethazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.promethazine, 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.propylhexedrinephentermine and propylhexedrine both decrease sedation. Use Caution/Monitor.phentermine and propylhexedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.protriptylineprotriptyline increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pseudoephedrinephentermine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.quazepamquazepam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.quetiapinequetiapine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.risperidonerisperidone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.salmeterolsalmeterol and phentermine both decrease sedation. Use Caution/Monitor.salmeterol and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.scullcapscullcap increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.secobarbitalsecobarbital increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.serdexmethylphenidate/dexmethylphenidateserdexmethylphenidate/dexmethylphenidate and phentermine both decrease sedation. Use Caution/Monitor.serdexmethylphenidate/dexmethylphenidate and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.shepherd's purseshepherd's purse increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.solriamfetolphentermine and solriamfetol both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.sufentanilsufentanil increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.tapentadoltapentadol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.temazepamtemazepam