Side-effect profile of sildenafil citrate (Viagra) in clinical practice

Objectives. Sildenafil citrate (Viagra) has been shown to be an effective t reatment for erectile dysfunction. Initial studies reported a high tolerabi lity and low incidence of certain characteristic adverse reactions. We soug ht to evaluate the incidence of side effects of sildenafil citrate, indepen dent of industry support and constraints, utilizing a heterogeneous cohort of patients from a university-based practice. Methods. A prospective, open-label, flexible-dose study of 256 patients tre ated with sildenafil citrate for erectile dysfunction was performed at a si ngle institution. The patients were questioned explicitly about the occurre nce of headache, flushing, dyspepsia, nasal congestion, visual changes, and other side effects. Results. The adverse reactions most commonly observed were flushing (30.8%) , headache (25.4%), nasal congestion (18.7%), and heartburn (10.5%). All ev ents were short lived and mild in nature. In the present study, 31.6% of pa tients experienced one or more adverse events. However, no one withdrew fro m the study because of the severity of these events. There was a significan t association between higher doses and the occurrence of side effects. Conclusions. The incidence of adverse events attributable to sildenafil cit rate may be higher than initially reported, but an explanation may be the m ethodology of data collection and the industry-independent nature of this s tudy. The side-effect profile is dose related and mild. Sildenafil citrate remains a safe and well-tolerated treatment for erectile dysfunction. UROLO GY 56: 474-476, 2000. (C) 2000, Elsevier Science Inc.