For men with penile dysfunction Viagra enables them to be able to respond to sexual stimulation. When a man is sexually aroused, the arteries in his penis relax and widen, allowing an increased amount of blood to flow into the penis. The effect of this increased blood flow causes the penis to become erect and hard.  Veins at the base of the penis become compressed, restricting the flow of blood from the penis thus maintaining the erection.          

When messages are sent from the brain, the arteries in the body that provide blood to the penis dilate allowing a greater flow. The signal that is by nitric oxide that is in blood. This activates the enzyme starting a molecule that is known as cGMP. The effect of this is to make the smooth muscle in the artery wall to soften causing the blood vessels to dilate.

The enzyme cGMP though is inhibited by the enzyme known as PDE. This result is that the arteries narrow which causing an erection to subside. Viagra works by inhibiting the PDE preventing it from dissolving the cGMP. As a result a normal erection is maintained, but only last while natural sexual stimulation remains.

Problems with blood vessels or nervous complaints can be the cause of  some men’s problem with erectile dysfunction. The manufacturer of Viagra, Pfizer, have worked on the problem of increasing the blood flow to the penis, so that when a man is sexually stimulated, that he can obtain and maintain an erection. After taking part in sex, the erection will go subside. Studies have shown that Viagra improves the erections in more than 80 percent in men.

For Viagra to work a man must be sexually stimulated either visually or in a tactile manner. If a man takes Viagra and is not sexually stimulated, he will not get an erection, Viagra is not an aphrodisiac. It is a prescription medication that helps men with erectile dysfunction to help improve their sex life.

During 1993 test were undertaken to see if Viagra™ could be used to treat erectile dysfunction. In these trials, Viagra™ was given to over 3,000 patients, who were aged between 19 to 87 years old. In 21 separate studies it proved to give statistically significant improvements when compared to the placebo.

Erectile dysfunction can also be a result of other medical complications. As a result, because of publicity received by Viagra™ has resulted in people seeing their doctor for help.