Not for sexual stimulation. Not to be used more than once daily. Serious CV event including MI, sudden cardiac death, unstable angina, ventricular arrhythmia, stroke, transient ischemic attacks, chest pain, palpitations, tachycardia, HTN; visual disturbance/sudden loss of vision, bone pain, sweating, fainting. Increased risk of NAION w/ patients who have already experienced NAION. Patients w/ CV disease taking nitrate vasodilator agent; erections lasting ≥4 hr; anatomical penis deformation (angulation, cavernosal fibrosis, or Peyronie's disease); conditions which may predispose to priapism eg, sickle cell anemia, multiple myeloma, leukemia. Assess CV status prior to therapy. Not recommended in combination w/ other PDE5 inhibitors. Concomitant use w/ α-blockers; potent CYP3A4 inhibitors eg, PIs, ketoconazole, itraconazole. Not recommended in combination w/ other therapies for erectile dysfunction. Severe renal & hepatic impairment (Child-Pugh class C). Not to be used in women or pregnant women. Childn <18 yr.