Sildenafil (Brand name: Viagra) is an oral treatment for erectile dysfunction, whether its cause is organic or psychogenic. Medical conditions that can lead to erectile dysfunction include diabetes, and circulatory, neurological, or urological issues. Traditionally, sildenafil needed to be taken at least an hour before intercourse, but Viagra Professional can be taken just 20 to 30 minutes before sexual activity due to its faster absorption rate. Like the original, it also enhances libido and staying power. Sildenafil is used to treat impotence in men and can help improve the ability to exercise in people with pulmonary arterial hypertension. It works by enhancing the vasodilatory effect of nitric oxide in the penis, thereby sustaining an erection. However, studies show that this drug cannot cure erectile dysfunction, prevent pregnancy, or stop the spread of sexually transmitted diseases.