Viagra

Viagra (Sildenafil citrate) is a drug used to treat erectile dysfunction (impotence) in males and pulmonary arterial hypertension (PAH). Viagra treats erectile dys function and works by relaxing muscles and increases blood flow to particular areas of the body (in this case, the penis, specifically). Its effects last up to four hours. The most common side effects of Viagra are headache, facial flushing, and upset stomach. Rarely, blurred vision, or sensitivity to light may briefly occur.

Viagra is solely active in relaxing muscles and increasing blood flow to the heart, lungs and penis due to PDE-5, yet vasodilation is not increased in other parts of the body.