increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.terbutalineterbutaline and phentermine both decrease sedation. Use Caution/Monitor.terbutaline and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.thioridazinethioridazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, 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.thiothixenethiothixene increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.topiramatetopiramate increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.tramadoltramadol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.trazodonetrazodone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.triazolamtriazolam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.triclofostriclofos increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.trifluoperazinetrifluoperazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.trifluoperazine, 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.trimipraminetrimipramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.triprolidinetriprolidine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.xylometazolinephentermine and xylometazoline both decrease sedation. Use Caution/Monitor.phentermine and xylometazoline both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.yohimbinephentermine and yohimbine both decrease sedation. Use Caution/Monitor.phentermine and yohimbine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.ziconotideziconotide increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.ziprasidoneziprasidone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (7)amantadineamantadine, phentermine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Potential for additive CNS stimulation.American ginsengAmerican ginseng increases effects of phentermine by pharmacodynamic synergism. Minor/Significance Unknown.desmopressindesmopressin increases effects of phentermine by pharmacodynamic synergism. Minor/Significance Unknown.eucalyptuseucalyptus increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.guaranaguarana increases effects of phentermine by pharmacodynamic synergism. Minor/Significance Unknown.sagesage increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.yerba mateyerba mate increases effects of phentermine by pharmacodynamic synergism. Minor/Significance Unknown.albuterolMonitor Closely (2)albuterol and phentermine both decrease sedation. Use Caution/Monitor. albuterol and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.alfentanilMonitor Closely (1)alfentanil increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.alprazolamMonitor Closely (1)alprazolam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amantadineMinor (1)amantadine, phentermine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Potential for additive CNS stimulation.American ginsengMinor (1)American ginseng increases effects of phentermine by pharmacodynamic synergism. Minor/Significance Unknown.amitriptylineMonitor Closely (1)amitriptyline increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)amitriptyline, 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.amobarbitalMonitor Closely (1)amobarbital increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amoxapineMonitor Closely (1)amoxapine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)amoxapine, 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.arformoterolMonitor Closely (2)arformoterol and phentermine both decrease sedation. Use Caution/Monitor. arformoterol and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.aripiprazoleMonitor Closely (1)aripiprazole increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.armodafinilMonitor Closely (1)armodafinil and phentermine both decrease sedation. Use Caution/Monitor.azelastineMonitor Closely (1)azelastine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.belladonna and opiumMonitor Closely (1)belladonna and opium increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.benazeprilMonitor Closely (1)phentermine decreases effects of benazepril by pharmacodynamic antagonism. Use Caution/Monitor.benperidolMonitor Closely (1)benperidol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.benzphetamineMonitor Closely (2)phentermine and benzphetamine both decrease sedation. Use Caution/Monitor. benzphetamine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.bromocriptineMonitor Closely (1)bromocriptine, phentermine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Hypertension, V tach.brompheniramineMonitor Closely (1)brompheniramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.buprenorphine buccalMonitor Closely (1)buprenorphine buccal increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.butabarbitalMonitor Closely (1)butabarbital increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.butalbitalMonitor Closely (1)butalbital increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.butorphanolMonitor Closely (1)butorphanol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.cabergolineSerious - Use Alternative (1)cabergoline, phentermine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.caffeineMonitor Closely (1)caffeine and phentermine both decrease sedation. Use Caution/Monitor.captoprilMonitor Closely (1)phentermine decreases effects of captopril by pharmacodynamic antagonism. Use Caution/Monitor. Phentermine may decrease the antihypertensive effect of ACE Inhibitors.carbinoxamineMonitor Closely (1)carbinoxamine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.chloral hydrateMonitor Closely (1)chloral hydrate increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.chlordiazepoxideMonitor Closely (1)chlordiazepoxide increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.chlorpheniramineMonitor Closely (1)chlorpheniramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.chlorpromazineMonitor Closely (2)chlorpromazine, 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. chlorpromazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.cinnarizineMonitor Closely (1)cinnarizine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.citalopramSerious - Use Alternative (1)citalopram, phentermine. Either increases toxicity of the other by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of serotonin syndrome.clemastineMonitor Closely (1)clemastine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.clomipramineMonitor Closely (1)clomipramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)clomipramine, 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.clonazepamMonitor Closely (1)clonazepam increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.clorazepateMonitor Closely (1)clorazepate increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.clozapineMonitor Closely (1)clozapine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.codeineMonitor Closely (1)codeine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.cyclizineMonitor Closely (1)cyclizine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.cyproheptadineMonitor Closely (1)cyproheptadine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.desfluraneSerious - Use Alternative (1)desflurane increases toxicity of phentermine by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of V tach, HTN.desipramineMonitor Closely (1)desipramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)desipramine, 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.desmopressinMinor (1)desmopressin increases effects of phentermine by pharmacodynamic synergism. Minor/Significance Unknown.dexchlorpheniramineMonitor Closely (1)dexchlorpheniramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dexfenfluramineMonitor Closely (2)phentermine and dexfenfluramine both decrease sedation. Use Caution/Monitor. dexfenfluramine and phentermine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.dexmedetomidineMonitor Closely (1)dexmedetomidine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dexmethylphenidateMonitor Closely (2)dexmethylphenidate 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.dextroamphetamineMonitor Closely (2)dextroamphetamine 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.dextromoramideMonitor Closely (1)dextromoramide increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.diamorphineMonitor Closely (1)diamorphine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dichlorphenamideMonitor Closely (1)dichlorphenamide and phentermine both decrease serum potassium. Use Caution/Monitor.diethylpropionMonitor Closely (2)phentermine 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 hclMonitor Closely (1)difenoxin hcl increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dihydroergotamineSerious - Use Alternative (1)dihydroergotamine, phentermine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.dihydroergotamine intranasalSerious - Use Alternative (1)dihydroergotamine intranasal, phentermine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.diltiazemMonitor Closely (1)phentermine will decrease the level or effect of diltiazem by pharmacodynamic antagonism. Use Caution/Monitor. Amphetamines may diminish antihypertensive effects of diltiazem. Monitor BP.dimenhydrinateMonitor Closely (1)dimenhydrinate increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.diphenhydramineMonitor Closely (1)diphenhydramine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.diphenoxylate hclMonitor Closely (1)diphenoxylate hcl increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dipipanoneMonitor Closely (1)dipipanone increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.dobutamineMonitor Closely (2)dobutamine 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.dopamineMonitor Closely (2)phentermine 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.dopexamineMonitor Closely (2)dopexamine 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.doxapramSerious - Use Alternative (1)doxapram increases effects of phentermine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Additive pressor effect.doxepinMonitor Closely (1)doxepin increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)doxepin, 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.droperidolMonitor Closely (1)droperidol increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.droxidopaMonitor Closely (1)phentermine and droxidopa both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. May increase risk for supine hypertensionduloxetineSerious - Use Alternative (1)duloxetine, phentermine. Either increases toxicity of the other by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of serotonin syndrome.ephedrineMonitor Closely (3)ephedrine, phentermine. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. ephedrine 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.epinephrineMonitor Closely (2)epinephrine 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 inhaledMonitor Closely (1)phentermine, epinephrine inhaled. Either increases effects of the other by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.epinephrine racemicMonitor Closely (2)epinephrine 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.ergoloid mesylatesSerious - Use Alternative (1)ergoloid mesylates, phentermine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.ergotamineSerious - Use Alternative (1)ergotamine, phentermine. Mechanism: pharmacodynamic synergism. Contraindicated. Additive vasospasm; risk of hypertension.escitalopramSerious - Use Alternative (1)escitalopram, phentermine. Either increases toxicity of the other by Mechanism: unknown. Avoid or Use Alternate Drug. Risk of serotonin syndrome.esketamine intranasalMonitor Closely (1)esketamine intranasal, phentermine. Either increases toxicity of the other by sympathetic (adrenergic)