Sildenafil makes the blood vessels become wider. This lowers the blood pressure. Sildenafil mostly works in the penis and in the lungs. This medicine increases blood flow to the penis. This helps the penis become erect during sexual intercourse. Sildenafil also helps pulmonary hypertension. Because this medicine makes the blood vessels wider, it makes it easier for blood to flow. Sildenafil was patented in 1996 and first made to sell in 1998.
- eMedicine. "Erectile Dysfunction - Treatment". Retrieved 26 February 2010.