First oral drug for male impotence, generic name sildenafil. Before the FDA approved Viagra in 1998, impotence was treated with surgical implants, suppositories, pumps, and drugs injected into the penis. Taken as a pill shortly before sexual intercourse, Viagra selectively dilates blood vessels in the penis, improving blood flow and allowing a natural sexual response. It works in about 70percnt of cases; it should not be used by anyone taking nitroglycerin or with heart problems, hypotension, hypertension, recent stroke, or certain eye disorders.

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