Erectile dysfunction, also called, as impotence is the inability to get or keep an erection firm enough for sexual intercourse. Any kind of disorder that causes injury to the nerves or impairs blood flow in the penis has the potential to cause ED. It has been observed that the incidence of impotence increases with age.

According to a survey, about 5 percent of 40-year-old men and between 15 and 25 percent of 65-year-old men experience ED. In older men, this condition usually has a physical cause, such as an injury, disease, or side effects of certain drugs.

The treatments of erectile dysfunction are many. One can go for surgical treatment or try medication. The treatment, however, depends on the root cause of the problem. The growing awareness that impotence can be treated at any age is helping more and more men to come out and discuss their problem.

The most publicized treatment was the introduction of the oral drug sildenafil citrate (Viagra) in 1998. This was the first Food and Drug Administration (FDA) approved pill to treat ED. Since that time, more such have been approved and introduced in the market. These are introduced only after they are tested for safety and effectiveness.

Viagra belongs to a class of drugs called phosphodiesterase (PDE) inhibitors. Taken an hour before sexual activity, this drugs work by enhancing the effects of nitric oxide, a chemical that relaxes smooth muscles in the penis during sexual stimulation and allows increased blood flow.

Viagra is easily available and anybody can buy Viagra. These days it is also available online. However, Viagra should not be used more than once a day. Men who take nitrate-based drugs such as nitroglycerin for heart problems should not use this drug because it may result in a sudden drop in blood pressure.