What is Sildenafil?

Sildenafil, the active ingredient in Viagra, helps men achieve and maintain an erection satisfactory for sexual activity. It blocks the chemicals that drain blood from the penis when a man has, or is trying to have, an erection.

To understand how Sildenafil treats erectile dysfunction (ED) requires understanding how someone gets an erection. It starts when a man is stimulated by an erotic thought or sexual contact. The brain then produces nitric oxide. That leads to a series of chemical reactions in the blood vessels of the penis that results in 6 times the blood flow getting to the penis. An erection might last indefinitely if it weren’t for chemicals in the body called phosphodiesterases. They work at reversing the process that is keeping the penis erect. Usually there is a balance between the chemicals as they pull in opposite directions. That balance results in an erection lasting for as long as it is needed; the phosphodiesterases do their job when they should, but no sooner.

Sildenafil interferes with the process that allows blood to leave the penis. Men with erectile dysfunction benefit from having the chemicals leading to the erection outweigh the actions of the phosphodiesterases that cause the penis to lose its firmness. That is what the medications for erectile dysfunction do; they block, or inhibit, the phosphodiesterases (that’s why they are called phosphodiesterase inhibitors). Sildenafil lets the forces that give a man an erection rule over those that would not.

The result is a firmer erection that lasts longer.