In some cases, ED can cause a strain on relationships and impact self-esteem. In these studies, involving about patients, analyses of patient diaries showed no effect of VIAGRA on rates of attempted intercourse about 2 per week , but there was clear treatment-related improvement in sexual function: per patient weekly success rates averaged 1. The generics cost much less, and—in the case of sildenafil—come in 20 mg doses. VIAGRA sildenafil citrate is supplied as blue, film-coated, rounded-diamond-shaped tablets containing sildenafil citrate equivalent to the nominally indicated amount of sildenafil and debossed on the obverse and reverse sides as follows: 25 mg. Side effects Side effects of oral ED medicines are often mild. Other conditions that may disqualify you from an ED prescription include a history of stroke, kidney or liver disease, cancer, diabetes, or a bleeding disorder.Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes . Viagra (sildenafil): As the first FDA-approved PDE5 inhibitor for ED, sildenafil is taken 30 minutes to four hours before sexual intercourse to help achieve . Viagra comes as tablets that you take by mouth, when needed. Available strengths: 25 mg, 50 mg, mg. Viagra comes in these strengths: 25 milligram (mg), .