tincture increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxazepamoxazepam increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxycodoneoxycodone increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxymorphoneoxymorphone increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.oxytocinoxytocin increases effects of methamphetamine by pharmacodynamic synergism. Use Caution/Monitor.paliperidonepaliperidone increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.papaveretumpapaveretum increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.parecoxibparecoxib will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.peginterferon alfa 2bpeginterferon alfa 2b, methamphetamine. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.pentazocinepentazocine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pentobarbitalpentobarbital increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazineperphenazine will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.perphenazine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.perphenazine, methamphetamine. 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.phendimetrazinemethamphetamine and phendimetrazine both decrease sedation. Use Caution/Monitor.methamphetamine and phendimetrazine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.phenobarbitalphenobarbital increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.phenterminemethamphetamine 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.phenylephrinemethamphetamine and phenylephrine both decrease sedation. Use Caution/Monitor.methamphetamine and phenylephrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.phenylephrine POmethamphetamine and phenylephrine PO both decrease sedation. Use Caution/Monitor.methamphetamine and phenylephrine PO both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.pholcodinepholcodine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pimozidepimozide increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pirbuterolpirbuterol and methamphetamine both decrease sedation. Use Caution/Monitor.pirbuterol and methamphetamine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.primidoneprimidone increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.prochlorperazineprochlorperazine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.prochlorperazine, methamphetamine. 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, methamphetamine. 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 methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.promethazine, methamphetamine. 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.propafenonepropafenone will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.propylhexedrinemethamphetamine and propylhexedrine both decrease sedation. Use Caution/Monitor.methamphetamine and propylhexedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.protriptylineprotriptyline increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pseudoephedrinemethamphetamine and pseudoephedrine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.quazepamquazepam increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.quetiapinequetiapine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.quinacrinequinacrine will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.ranolazineranolazine will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.risperidonerisperidone increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.ritonavirritonavir will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.rolapitantrolapitant will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Rolapitant may increase plasma concentrations of CYP2D6 substrates for at least 28 days following rolapitant administration.salmeterolsalmeterol and methamphetamine both decrease sedation. Use Caution/Monitor.salmeterol and methamphetamine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.scullcapscullcap increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.secobarbitalsecobarbital increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.serdexmethylphenidate/dexmethylphenidateserdexmethylphenidate/dexmethylphenidate and methamphetamine both decrease sedation. Use Caution/Monitor.serdexmethylphenidate/dexmethylphenidate and methamphetamine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.sertralinesertraline will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.shepherd's purseshepherd's purse increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.sodium acid phosphatesodium acid phosphate decreases levels of methamphetamine by increasing renal clearance. Use Caution/Monitor.solriamfetolmethamphetamine and solriamfetol both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.sufentanilsufentanil increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.sufentanil SLsufentanil SL, methamphetamine. 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.tapentadoltapentadol increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.temazepamtemazepam increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.terbinafineterbinafine will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.terbutalineterbutaline and methamphetamine both decrease sedation. Use Caution/Monitor.terbutaline and methamphetamine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.thioridazinethioridazine will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.thioridazine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, methamphetamine. 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 methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.tipranavirtipranavir will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.topiramatetopiramate increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Modify Therapy/Monitor Closely.tramadoltramadol increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.trazodonetrazodone increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. trazodone increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Significant - Monitor Closely..methamphetamine increases toxicity of trazodone by Other (see comment). Use Caution/Monitor. Comment: Amphetamines may increase the toxicity of serotonin modulators, increasing the risk of serotonin syndrome. .triazolamtriazolam increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.triclofostriclofos increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.trifluoperazinetrifluoperazine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.trifluoperazine, methamphetamine. 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 methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.triprolidinetriprolidine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.venlafaxinevenlafaxine will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.xylometazolinemethamphetamine and xylometazoline both decrease sedation. Use Caution/Monitor.methamphetamine and xylometazoline both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.yohimbinemethamphetamine and yohimbine both decrease sedation. Use Caution/Monitor.methamphetamine and yohimbine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.ziconotideziconotide increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.ziprasidoneziprasidone increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (15)amantadineamantadine, methamphetamine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Potential for additive CNS stimulation.American ginsengAmerican ginseng increases effects of methamphetamine by pharmacodynamic synergism. Minor/Significance Unknown.celandinecelandine increases effects of methamphetamine by unspecified interaction mechanism. Minor/Significance Unknown. Based on animal studies.desmopressindesmopressin increases effects of methamphetamine by pharmacodynamic synergism. Minor/Significance Unknown.dexlansoprazoledexlansoprazole decreases levels of methamphetamine by Other (see comment). Minor/Significance Unknown. Comment: Time to maximum concentration (Tmax) of amphetamine is decreased compared to when administered alone; monitor patients for changes in clinical effect and adjust therapy based on clinical response.esomeprazoleesomeprazole decreases levels of methamphetamine by Other (see comment). Minor/Significance Unknown. Comment: Time to maximum concentration (Tmax) of amphetamine is decreased compared to when administered alone; monitor patients for changes in clinical effect and adjust therapy based on clinical response.ethosuximidemethamphetamine decreases levels of ethosuximide by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.eucalyptuseucalyptus increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.guaranaguarana increases effects of methamphetamine by pharmacodynamic synergism. Minor/Significance Unknown.lansoprazolelansoprazole decreases levels of methamphetamine by Other (see comment). Minor/Significance Unknown. Comment: Time to maximum concentration (Tmax) of amphetamine is decreased compared to when administered alone; monitor patients for changes in clinical effect and adjust therapy based on clinical response.omeprazoleomeprazole decreases levels of methamphetamine by Other (see comment). Minor/Significance Unknown. Comment: Time to maximum concentration (Tmax) of amphetamine is decreased compared to when administered alone; monitor patients for changes in clinical effect and adjust therapy based on clinical response.pantoprazolepantoprazole decreases levels of methamphetamine by Other (see comment). Minor/Significance Unknown. Comment: Time to maximum concentration (Tmax) of amphetamine is decreased compared to when administered alone; monitor patients for changes in clinical effect and adjust therapy based on clinical response.rabeprazolerabeprazole decreases levels of methamphetamine by Other (see comment). Minor/Significance Unknown. Comment: Time to maximum concentration (Tmax) of amphetamine is decreased compared to when administered alone; monitor patients for changes in clinical effect and adjust therapy based on clinical response.sagesage increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Minor/Significance Unknown.yerba mateyerba mate increases effects of methamphetamine by pharmacodynamic synergism. Minor/Significance Unknown.abirateroneMonitor Closely (1)abiraterone increases levels of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Avoid coadministration of abiraterone with substrates of CYP2D6. If alternative therapy cannot be used, exercise caution and consider a dose reduction of the CYP2D6 substrate.albuterolMonitor Closely (2)albuterol and methamphetamine both decrease sedation. Use Caution/Monitor. albuterol and methamphetamine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.alfentanilMonitor Closely (1)alfentanil increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.alprazolamMonitor Closely (1)alprazolam increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amantadineMinor (1)amantadine, methamphetamine. 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 methamphetamine by pharmacodynamic synergism. Minor/Significance Unknown.amiodaroneMonitor Closely (1)amiodarone will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.amitriptylineMonitor Closely (1)amitriptyline increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)amitriptyline, methamphetamine. 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.ammonium chlorideMonitor Closely (1)ammonium chloride decreases levels of methamphetamine by increasing renal clearance. Use Caution/Monitor.amobarbitalMonitor Closely (1)amobarbital increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.amoxapineMonitor Closely (1)amoxapine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.Serious - Use Alternative (1)amoxapine, methamphetamine. 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 methamphetamine both decrease sedation. Use Caution/Monitor. arformoterol and methamphetamine both increase sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.aripiprazoleMonitor Closely (1)aripiprazole increases and methamphetamine decreases sedation. Effect of interaction is