Sildenafil: desired and undesired effects.

About 50% of men aged between 40–70 years have some degree of erectile dysfunction, and 30% report moderate to severe impotence (Goldstein and Beavo, 1998). Vascular disease, diabetes, prostate surgery, psychiatric disorders and concomitant drug therapy may predispose to impotence, and psychological factors exacerbate the problem. Sildenafil (Viagra, Pfizer) is the first orally active treatment for impotence, and has attracted much attention in the lay and professional press. This article describes some of its wanted and unwanted effects.