AdultPediatricDosage Forms & Strengths tablet 1mg (Propecia) 5mg (Proscar) Benign Prostatic Hyperplasia Proscar: 5 mg PO qDay; assess response after 12 weeks to 6 months Androgenic Alopecia (Men Only) Propecia: 1 mg PO qDay for at least 3 months Female Hirsutism (Off-label) 5 mg PO qDay Dosage Modifications Renal impairment: Dose adjustment not necessary Hepatic impairment: Caution in liver dysfunction; monitorNot indicatedInteraction CheckerEnter a drug name and finasterideNo Results No Interactions Found Interactions FoundContraindicatedSerious - Use AlternativeSignificant - Monitor CloselyMinorAll Interactions Sort By: SeverityName Contraindicated (0)Serious - Use Alternative (0)Monitor Closely (16)carbamazepinecarbamazepine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.clarithromycinclarithromycin will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin baseerythromycin base will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin ethylsuccinateerythromycin ethylsuccinate will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin lactobionateerythromycin lactobionate will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin stearateerythromycin stearate will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.isoniazidisoniazid will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.itraconazoleitraconazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ketoconazoleketoconazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.letermovirletermovir increases levels of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.levoketoconazolelevoketoconazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nefazodonenefazodone will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nevirapinenevirapine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rifabutinrifabutin will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rifampinrifampin will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.St John's WortSt John's Wort will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (55)amobarbitalamobarbital will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.aprepitantaprepitant will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.armodafinilarmodafinil will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.artemether/lumefantrineartemether/lumefantrine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.atazanaviratazanavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.bosentanbosentan will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.budesonidebudesonide will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.butabarbitalbutabarbital will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.butalbitalbutalbital will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.conivaptanconivaptan will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.cortisonecortisone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.darifenacindarifenacin will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.darunavirdarunavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.dasatinibdasatinib will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.dexamethasonedexamethasone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.DHEA, herbalDHEA, herbal will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.dronedaronedronedarone will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.efavirenzefavirenz will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.eslicarbazepine acetateeslicarbazepine acetate will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.etravirineetravirine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.fluconazolefluconazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.fludrocortisonefludrocortisone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.fosamprenavirfosamprenavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.fosaprepitantfosaprepitant will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.fosphenytoinfosphenytoin will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.grapefruitgrapefruit will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.griseofulvingriseofulvin will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.hydrocortisonehydrocortisone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.indinavirindinavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.lapatiniblapatinib will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.lumefantrinelumefantrine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.marijuanamarijuana will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.methylprednisolonemethylprednisolone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.metronidazolemetronidazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.miconazole vaginalmiconazole vaginal will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.nelfinavirnelfinavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.nifedipinenifedipine will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.nilotinibnilotinib will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.oxcarbazepineoxcarbazepine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.pentobarbitalpentobarbital will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.phenobarbitalphenobarbital will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.phenytoinphenytoin will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.posaconazoleposaconazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.prednisoneprednisone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.primidoneprimidone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.quinupristin/dalfopristinquinupristin/dalfopristin will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.rifapentinerifapentine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.ritonavirritonavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.rufinamiderufinamide will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.saw palmettosaw palmetto increases effects of finasteride by pharmacodynamic synergism. Minor/Significance Unknown.secobarbitalsecobarbital will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.topiramatetopiramate will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.verapamilverapamil will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.voriconazolevoriconazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.zafirlukastzafirlukast will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.amobarbitalMinor (1)amobarbital will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.aprepitantMinor (1)aprepitant will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.armodafinilMinor (1)armodafinil will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.artemether/lumefantrineMinor (1)artemether/lumefantrine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.atazanavirMinor (1)atazanavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.bosentanMinor (1)bosentan will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.budesonideMinor (1)budesonide will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.butabarbitalMinor (1)butabarbital will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.butalbitalMinor (1)butalbital will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.carbamazepineMonitor Closely (1)carbamazepine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.clarithromycinMonitor Closely (1)clarithromycin will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.conivaptanMinor (1)conivaptan will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.cortisoneMinor (1)cortisone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.darifenacinMinor (1)darifenacin will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.darunavirMinor (1)darunavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.dasatinibMinor (1)dasatinib will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.dexamethasoneMinor (1)dexamethasone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.DHEA, herbalMinor (1)DHEA, herbal will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.dronedaroneMinor (1)dronedarone will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.efavirenzMinor (1)efavirenz will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.erythromycin baseMonitor Closely (1)erythromycin base will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin ethylsuccinateMonitor Closely (1)erythromycin ethylsuccinate will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin lactobionateMonitor Closely (1)erythromycin lactobionate will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.erythromycin stearateMonitor Closely (1)erythromycin stearate will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.eslicarbazepine acetateMinor (1)eslicarbazepine acetate will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.etravirineMinor (1)etravirine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.fluconazoleMinor (1)fluconazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.fludrocortisoneMinor (1)fludrocortisone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.fosamprenavirMinor (1)fosamprenavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.fosaprepitantMinor (1)fosaprepitant will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.fosphenytoinMinor (1)fosphenytoin will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.grapefruitMinor (1)grapefruit will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.griseofulvinMinor (1)griseofulvin will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.hydrocortisoneMinor (1)hydrocortisone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.indinavirMinor (1)indinavir will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.isoniazidMonitor Closely (1)isoniazid will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.itraconazoleMonitor Closely (1)itraconazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ketoconazoleMonitor Closely (1)ketoconazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.lapatinibMinor (1)lapatinib will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.letermovirMonitor Closely (1)letermovir increases levels of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.levoketoconazoleMonitor Closely (1)levoketoconazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.lumefantrineMinor (1)lumefantrine will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.marijuanaMinor (1)marijuana will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.methylprednisoloneMinor (1)methylprednisolone will decrease the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.metronidazoleMinor (1)metronidazole will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.miconazole vaginalMinor (1)miconazole vaginal will increase the level or effect of finasteride by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.nefazodoneMonitor Closely (1)nefazodone will increase the level or