of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with duvelisib increases AUC of a sensitive CYP3A4 substrate which may increase the risk of toxicities of these drugs. Consider reducing the dose of the sensitive CYP3A4 substrate and monitor for signs of toxicities of the coadministered sensitive CYP3A substrate.efavirenzefavirenz increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.elagolixelagolix decreases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.eliglustateliglustat increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the concomitant drug and titrate to clinical effect.elvitegravir/cobicistat/emtricitabine/tenofovir DFelvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP2D6 inhibitor; caution with CYP2D6 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.encorafenibencorafenib, tamsulosin. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.erythromycin baseerythromycin base will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin base increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.erythromycin ethylsuccinateerythromycin ethylsuccinate increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.erythromycin ethylsuccinate will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin lactobionateerythromycin lactobionate increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.erythromycin lactobionate will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin stearateerythromycin stearate will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin stearate increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.etravirineetravirine will decrease the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.isoniazidisoniazid will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fedratinibfedratinib will increase the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.fedratinib will increase the level or effect of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.fluconazolefluconazole increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.fluoxetinefluoxetine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.fosaprepitantfosaprepitant increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.grapefruitgrapefruit increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.haloperidolhaloperidol increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.haloperidol increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.iloperidoneiloperidone increases levels of tamsulosin 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.imatinibimatinib increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.imipramineimipramine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.isoniazidisoniazid increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.istradefyllineistradefylline will increase the level or effect of tamsulosin 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.itraconazoleitraconazole will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ketoconazoleketoconazole will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ketoconazole increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.lapatiniblapatinib increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.letermovirletermovir increases levels of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.larotrectiniblarotrectinib will increase the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.lenacapavirlenacapavir will increase the level or effect of tamsulosin 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.levoketoconazolelevoketoconazole will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.levoketoconazole increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.lidocainelidocaine increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.lidocaine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.nefazodonenefazodone will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.lopinavirlopinavir increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.lorcaserinlorcaserin increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.lorlatiniblorlatinib will decrease the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.methadonemethadone increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.methimazolemethimazole increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.metronidazolemetronidazole increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.mifepristonemifepristone will increase the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.mitotanemitotane decreases levels of tamsulosin 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.nafcillinnafcillin will decrease the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nefazodonenefazodone increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.nicardipinenicardipine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.oxymetazoline topicaloxymetazoline topical increases and tamsulosin decreases sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Effect of interaction is not clear, use caution. Use Caution/Monitor.paroxetineparoxetine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.pseudoephedrinepseudoephedrine decreases effects of tamsulosin by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor.pyrimethaminepyrimethamine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.quinidinequinidine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.quininequinine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.ranolazineranolazine increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.ribociclibribociclib will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ribociclib will increase the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rifabutinrifabutin will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rifabutin will decrease the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rifampinrifampin will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rifapentinerifapentine will decrease the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.St John's WortSt John's Wort will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ritonavirritonavir increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.Minor (17)acetazolamideacetazolamide will increase the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.amobarbitalamobarbital will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.anastrozoleanastrozole will increase the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.aprepitantaprepitant will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.armodafinilarmodafinil will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.artemether/lumefantrineartemether/lumefantrine will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.atazanaviratazanavir will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.benazepriltamsulosin, benazepril. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. May increase risk of hypotension.bosentanbosentan will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.budesonidebudesonide will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.butabarbitalbutabarbital will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.butalbitalbutalbital will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.captopriltamsulosin, captopril. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. May increase risk of hypotension.conivaptanconivaptan will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.cortisonecortisone will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.cyclophosphamidecyclophosphamide will increase the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.cyclosporinecyclosporine will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.abametapirSerious - Use Alternative (1)abametapir increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. For 2 weeks after abametapir application, avoid taking drugs that are CYP3A4 substrates. If not feasible, avoid use of abametapir.abirateroneMonitor Closely (1)abiraterone increases levels of tamsulosin 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.acetazolamideMinor (1)acetazolamide will increase the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.alfuzosinSerious - Use Alternative (1)alfuzosin, tamsulosin. Either increases effects of the other by additive vasodilation. Avoid or Use Alternate Drug. Risk of hypotension.amifostineMonitor Closely (1)amifostine, tamsulosin. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration with blood pressure lowering agents may increase the risk and severity of hypotension associated with amifostine. When amifostine is used at chemotherapeutic doses, withhold blood pressure lowering medications for 24 hr prior to amifostine; if blood pressure lowering medication cannot be withheld, do not administer amifostine.amiodaroneMonitor Closely (2)amiodarone increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be neeed for coadministered drugs that are predominantly metabolized by CYP3A. amiodarone increases levels of tamsulosin by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.amobarbitalMonitor Closely (1)amobarbital will decrease the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)amobarbital will decrease the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.anastrozoleMinor (1)anastrozole will increase the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.apalutamideSerious - Use Alternative (1)apalutamide will decrease the level or effect of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.aprepitantMonitor Closely (1)aprepitant increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.Minor (1)aprepitant will increase the level or effect of dutasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance