Viagra is used to treat impotence in men. Viagra increases the body's ability to achieve and maintain an erection during sexual stimulation. Viagra does not protect you from getting sexually transmitted diseases, including HIV.
An erection can occur when sexual stimulation triggers your brain to send nerve signals to your penis. These signals cause the muscles within the arteries of your penis to relax resulting in more blood flow through the penis, which causes your penis to get hard. Normally, blood stays trapped in the penis until the completion of sexual activity.
Sildenfil Citrate (Viagra) first became available in 1998. The little blue pill comes in doses of 25, 50, 100, 120, 150 and 200 milligrams. No more than one pill per day can be taken. Directions state that the pill should be taken between one half hour and four hours before sexual intercourse. The pill should be taken on an empty stomach, since the meal may interfere with the effectiveness of the drug.
When you have erectile dysfunction (ED), also known as impotence, you have a problem getting or maintaining an erection long enough for sex. ED happens when not enough blood flows to your penis when you are sexually stimulated. ED may not be the same for all men. Some men are not able to get an erection at all. Some men can get an erection, but it's not hard enough for sex, and other men get a firm erection but lose it before or during sexual activity.