Objectives: Sildenafil citrate (Viagra) has been shown to be an effective treatment for erectile dysfunction. Initial studies reported a high tolerability and low incidence of certain characteristic adverse reactions. We sought to evaluate the incidence of side effects of sildenafil citrate, independent 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 treated with sildenafil citrate for erectile dysfunction was performed at a single institution. The patients were questioned explicitly about the occurrence 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 events were short lived and mild in nature. In the present study, 31.6% of patients experienced one or more adverse events. However, no one withdrew from the study because of the severity of these events. There was a significant association between higher doses and the occurrence of side effects.
Conclusions: The incidence of adverse events attributable to sildenafil citrate may be higher than initially reported, but an explanation may be the methodology of data collection and the industry-independent nature of this study. The side-effect profile is dose related and mild. Sildenafil citrate remains a safe and well-tolerated treatment for erectile dysfunction.