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.pentobarbitalSerious - Use Alternative (1)pentobarbital 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 levelsphenobarbitalSerious - Use Alternative (1)phenobarbital 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 levelsphenoxybenzamineSerious - Use Alternative (1)sildenafil increases effects of phenoxybenzamine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.phentolamineSerious - Use Alternative (1)sildenafil increases effects of phentolamine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.phenytoinSerious - Use Alternative (1)phenytoin 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 levelspindololMonitor Closely (1)pindolol 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.posaconazoleMonitor Closely (1)posaconazole will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.prazosinSerious - Use Alternative (1)sildenafil increases effects of prazosin by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.primidoneSerious - Use Alternative (1)primidone 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 levelspropranololMonitor Closely (1)propranolol 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.ribociclibMonitor Closely (1)ribociclib will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rifabutinMonitor Closely (1)rifabutin 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 levelsrifampinMonitor Closely (1)rifampin 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 levelsrifapentineMonitor Closely (1)rifapentine 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 levelsriociguatContraindicated (1)sildenafil, riociguat. Either increases effects of the other by additive vasodilation. Contraindicated. Coadministration of PDE-5 inhibitors (eg, avanafil, sildenafil, tadalafil, vardenafil) and guanylate cyclase stimulators (eg, riociguat) is contraindicated due to risk of additive hypotension; do not administer within 24 hr of each other.ritonavirSerious - Use Alternative (1)ritonavir 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.sapropterinMinor (1)sapropterin, sildenafil. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Possible additive vasorelaxation, leading to low blood pressure.saquinavirMonitor Closely (1)saquinavir increases levels of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. Increased risk of priapism, hypotension, and other adverse effects.secobarbitalMonitor Closely (1)secobarbital will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.silodosinSerious - Use Alternative (1)sildenafil increases effects of silodosin by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.sotalolMonitor Closely (1)sotalol 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.St John's WortSerious - Use Alternative (1)St 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 levelsstiripentolMonitor Closely (1)stiripentol, sildenafil. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.tamsulosinMonitor Closely (1)sildenafil, tamsulosin. Either increases effects of the other by additive vasodilation. Use Caution/Monitor. Risk of hypotension.tazemetostatMonitor Closely (1)tazemetostat will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.tecovirimatMonitor Closely (1)tecovirimat will decrease the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.terazosinSerious - Use Alternative (1)sildenafil increases effects of terazosin by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.timololMonitor Closely (1)timolol 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.tipranavirMonitor Closely (1)tipranavir increases levels of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity. Increased risk of priapism, hypotension, and other adverse effects.tobramycin inhaledMonitor Closely (1)tobramycin inhaled and sildenafil both increase nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Avoid concurrent or sequential use to decrease risk for ototoxicitytucatinibSerious - Use Alternative (1)tucatinib 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.verapamilMonitor Closely (1)verapamil will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.vericiguatContraindicated (1)sildenafil, vericiguat. Either increases effects of the other by pharmacodynamic synergism. Contraindicated. Coadministration of vericiguat with PDE-5 inhibitors may result in additive hypotensive effects.voriconazoleMonitor Closely (1)voriconazole will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.voxelotorSerious - Use Alternative (1)voxelotor 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.zafirlukastMonitor Closely (1)zafirlukast will increase the level or effect of sildenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. >10% Viagra 25-mg dose Headache (16%) 50-mg dose Headache (21%) Flushing (19%) 100-mg dose H5 Headache (28%) Flushing (18%) Dyspepsia (17%) Abnormal vision (11%) Revatio Headache (46%) Dyspepsia (13%) 1-10% Viagra 25-mg dose Flushing (10%) Nasal congestion (4%) Dyspepsia (3%) Back pain (3%) Dizziness (3%) Myalgia (2%) Nausea (2%) Abnormal vision (1%) Rash (1%) 50-mg dose Dyspepsia (9%) Nasal congestion (4%) Back pain (4%) Dizziness (4%) Nausea (3%) Abnormal vision (2%) Myalgia (2%) Rash (2%) 100-mg dose Nasal congestion (9%) Back pain (4%) Myalgia (4%) Nausea (3%) Dizziness (3%) Rash (3%) <2% with potential causal relationship Body as a whole: Face edema, photosensitivity reaction, shock, asthenia, pain, chills, accidental fall, abdominal pain, allergic reaction, chest pain, accidental injury Cardiovascular: Angina pectoris, AV block, migraine, syncope, tachycardia, palpitation, hypotension, postural hypotension, myocardial ischemia, cerebral thrombosis, cardiac arrest, heart failure, abnormal electrocardiogram, cardiomyopathy Digestive: Vomiting, glossitis, colitis, dysphagia, gastritis, gastroenteritis, esophagitis, stomatitis, dry mouth, liver function tests abnormal, rectal hemorrhage, gingivitis Hemic and lymphatic: Anemia and leukopenia Metabolic and nutritional: Thirst, edema, gout, unstable diabetes, hyperglycemia, peripheral edema, hyperuricemia, hypoglycemic reaction, hypernatremia Musculoskeletal: Arthritis, arthrosis, myalgia, tendon rupture, tenosynovitis, bone pain, myasthenia, synovitis Nervous: Ataxia, hypertonia, neuralgia, neuropathy, paresthesia, tremor, vertigo, depression, insomnia, somnolence, abnormal dreams, reflexes decreased, hypesthesia Respiratory: Asthma, dyspnea, laryngitis, pharyngitis, sinusitis, bronchitis, sputum increased, cough increased Skin and appendages: Urticaria, herpes simplex, pruritus, sweating, skin ulcer, contact dermatitis, exfoliative dermatitis Special senses: Sudden decrease or loss of hearing, mydriasis, conjunctivitis, photophobia, tinnitus, eye pain, ear pain, eye hemorrhage, cataract, dry eyes Urogenital: Cystitis, nocturia, urinary frequency, breast enlargement, urinary incontinence, abnormal ejaculation, genital edema and anorgasmia Revatio Flushing (10%) Epistaxis (9%) Diarrhea (9%) Insomnia (7%) Myalgia (7%) Dyspnea exacerbate (7%) Erythema (6%) Pyrexia (6%) Rhinitis (4%) Gastritis (3%) Sinusitis (3%) Paresthesia (3%) Postmarketing Reports Cardiovascular and cerebrovascular: Serious cardiovascular (CV), cerebrovascular, and vascular events, including myocardial infarction, sudden cardiac death, ventricular arrhythmia, cerebrovascular hemorrhage, transient ischemic attack, hypertension, subarachnoid and intracerebral hemorrhages, and pulmonary hemorrhage (most, but not all, of these patients had preexisting CV risk factors) Hemic and lymphatic: vaso-occlusive crisis: In a small, prematurely terminated study of sildenafil in patients with pulmonary arterial hypertension (PAH) secondary to sickle cell disease, vaso-occlusive crises requiring hospitalization were commonly reported Nervous: Seizure, seizure recurrence, anxiety, and transient global amnesia Respiratory: Epistaxis Hearing: Cases of sudden decrease or loss of hearing reported postmarketing in temporal association with PDE5 inhibitors Ocular: Diplopia, temporary vision loss/decreased vision, ocular redness or bloodshot appearance, ocular burning, ocular swelling/pressure, increased intraocular pressure, retinal edema, retinal vascular disease or bleeding, and vitreous traction/detachment Nonarteritic anterior ischemic optic neuropathy (NAION), a cause of decreased vision including permanent loss of vision (reported rarely) Urogenital: Prolonged erection, priapism, and hematuria Contraindications Hypersensitivity Soluble guanylate cyclase (sGC) stimulators (eg, riociguat); concomitant use can cause hypotension Coadministration with nitrates Coadministration with nitrates (either regularly and/or intermittently) and nitric oxide donors Consistent with the effects of PDE5 inhibition on the nitric oxide/cyclic guanosine monophosphate pathway, PDE5 inhibitors may potentiate the hypotensive effects of nitrates A suitable time interval following PDE5 dosing for the safe administration of nitrates or nitric oxide donors has not been determined Cautions Elicits vasodilatory properties, resulting in mild and transient decreases in blood pressure; monitor for hypotension Use with caution in patients with anatomic deformation of penis (eg, angulation, cavernosal fibrosis, or Peyronie disease), conditions potentially predisposing to priapism (eg, sickle cell anemia, multiple myeloma, or leukemia), cardiovascular disease, bleeding disorders, active peptic ulcer disease, liver disease, renal impairment, multidrug antihypertensive regimens, retinitis pigmentosa, concomitant use of CYP3A4 inhibitors Pulmonary vasodilators may significantly worsen cardiovascular status of patients with pulmonary veno-occlusive disease Sudden decrease or loss of hearing, which may be accompanied by tinnitus and dizziness Stop sildenafil and seek medical care if a sudden loss of vision occurs in 1 or both eyes, which could be a sign of nonarteritic anterior ischemic optic neuropathy (NAION); use with caution, and only when the anticipated benefits outweigh the risks, most patients had underlying anatomic or vascular risk factors for developing NAION, including low cup to disc ratio (“crowded disc”); advise patients to seek immediate medical attention in the event of a sudden loss of vision May cause dose-related impairment of color discrimination; use in patients with retinitis pigmentosa not recommended Viagra Potential for cardiac risk with sexual activity in patients with preexisting cardiovascular disease; therefore, treatment for erectile dysfunction generally should not be instituted in men for whom sexual activity is inadvisable because of their underlying cardiovascular status Evaluate underlying causes of erectile dysfunction or BPH before initiating therapy Revatio In small, prematurely terminated study of patients with PAH secondary to sickle-cell disease, vaso-occlusive crises requiring hospitalization were more commonly reported by patients who received sildenafil than by those randomized to placebo; effectiveness of sildenafil in PAH secondary to sickle-cell anemia has not been established; the clinical relevance to men treated for erectile dysfunction with sildenafil is not known Epistaxis occurred in 13% of patients with PAH secondary to connective tissue disease (eg, scleroderma); this effect was not seen in idiopathic PAH; incidence was also higher in those receiving concomitant PO vitamin K antagonist therapy (9%) than in those not receiving such therapy (2%) Drug interaction overview CYP3A substrate (major route); CYP2C9 substrate (minor route) Nitrates Contraindicated Consistent with its