Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.phenytoinphenytoin will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levelsprazosinsildenafil increases effects of prazosin by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.primidoneprimidone will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levelsritonavirritonavir will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If used concomitantly, monitor for toxicities. Patients receiving indinavir with ritonavir should receive not more than 25 mg of sildenafil for treatment of erectile dysfunction in a 48-hour period, and patients receiving other protease inhibitors should use a lower initial sildenafil dose of 25 mg. Patient taking sildenafil for PAH with ritonavir is not recommended.silodosinsildenafil increases effects of silodosin by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.St John's WortSt John's Wort will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levelsterazosinsildenafil increases effects of terazosin by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.tucatinibtucatinib will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.voxelotorvoxelotor will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.Monitor Closely (87)acebutololacebutolol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.amifostineamifostine increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.amobarbitalamobarbital will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.aprepitantaprepitant will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.armodafinilarmodafinil will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.artemether/lumefantrineartemether/lumefantrine will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.atenololatenolol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.benazeprilsildenafil, benazepril. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Enhanced hypotensive effects.betaxololbetaxolol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.bisoprololbisoprolol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.bosentanbosentan will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levelsbutabarbitalbutabarbital will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.butalbitalbutalbital will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.captoprilsildenafil, captopril. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Both drugs lower blood pressure. Monitor blood pressure.carbamazepinecarbamazepine will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levelscarvedilolcarvedilol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.cenobamatecenobamate will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.cimetidinecimetidine will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.cyclosporinecyclosporine will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.darunavirdarunavir will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration with PDE-5 inhibitors may result in an increase in PDE-5 inhibitor-associated adverse reactions (eg, hypotension, syncope, visual disturbances and priapism).deferasiroxdeferasirox will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dexamethasonedexamethasone will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.diltiazemdiltiazem will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dronedaronedronedarone will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.duvelisibduvelisib will increase the level or effect of sildenafil 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 will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levelselagolixelagolix decreases levels of sildenafil 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.encorafenibencorafenib, sildenafil. 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.enzalutamideenzalutamide will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levelsepoprostenolepoprostenol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.erythromycin baseerythromycin base will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider a starting dose of 25 mg in patients treated with erythromycin.erythromycin ethylsuccinateerythromycin ethylsuccinate will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider a starting dose of 25 mg in patients treated with erythromycin.erythromycin lactobionateerythromycin lactobionate will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider a starting dose of 25 mg in patients treated with erythromycin.erythromycin stearateerythromycin stearate will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider a starting dose of 25 mg in patients treated with erythromycin.esmololesmolol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.etravirineetravirine will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levelsfedratinibfedratinib will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.fluconazolefluconazole will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fosamprenavirfosamprenavir will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.fosaprepitantfosaprepitant will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fosphenytoinfosphenytoin will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levelsgrapefruitgrapefruit will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.griseofulvingriseofulvin will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.hydrocortisonehydrocortisone will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.idelalisibidelalisib will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of sildenafil with strong CYP3A4 inhibitors is not recommended. If using Viagra, consider decreasing starting dose.iloperidoneiloperidone increases levels of sildenafil 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.indinavirindinavir will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. If used concomitantly, monitor for toxicities. Patients receiving indinavir with ritonavir should receive not more than 25 mg of sildenafil for treatment of erectile dysfunction in a 48-hour period, and patients receiving other protease inhibitors should use a lower initial sildenafil dose of 25 mg.isoniazidisoniazid will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.istradefyllineistradefylline will increase the level or effect of sildenafil 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 sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Not recommended during and 2 weeks after itraconazole treatment when sildenafil is used for pulmonary arterial hypertension.labetalollabetalol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.lapatiniblapatinib will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.lesinuradlesinurad decreases levels of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.letermovirletermovir increases levels of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.levamlodipinelevamlodipine, sildenafil. anti-hypertensive channel blocking. Use Caution/Monitor. When amlodipine and sildenafil were used in combination, each agent independently exerted its own blood pressure lowering effect.lorlatiniblorlatinib will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.maravirocmaraviroc, sildenafil. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of orthostatic hypotension.mavacamtensildenafil will increase the level or effect of mavacamten by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Inititiation of weak CYP2C19 inhibitors may require decreased mavacamten dose. metoprololmetoprolol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.miconazole vaginalmiconazole vaginal will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nebivololnebivolol increases effects of sildenafil by additive vasodilation. Use Caution/Monitor. Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications. Monitor blood pressure response to sildenafil in patients receiving concurrent blood pressure lowering therapy.nefazodonenefazodone will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.nevirapinenevirapine will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potent CYP3A4 inducers are expected to cause substantial decreases in sildenafil plasma levelsnifedipinenifedipine will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4