Viagra became a smashing success almost immediately upon its release. The success of Viagra was quickly evident in the level of popular interest it generated, and then in the big profits it brought in. The initial profit margin for Viagra was millions of dollars. Move forward a few years, and Viagra is now a billion dollar profit seller.

Viagra's success is rather a surprise, because Viagra is only available to one part of the population -- men -- and is a treatment for what was thought to be a fairly limited condition: erectile dysfunction. Consider this against, for example, a drug for depression: a depression drug is available to an entire population and treats a condition that's fairly common. How does Viagra's limited profile generate so much profit?

Viagra's profit success may be attributed to one of two things. The first explanation is that erectile dysfunction affects a considerable percentage of the male population. Men who were older and sickly, what would have to be a small percentage of the male population, were thought to be typical candidates for erectile dysfunction. But Viagra's broad sales numbers imply that more than just older, sickly men have erectile dysfunction. Perhaps erectile dysfunction is epidemic?

The other possible explanation for Viagra's sales success is that men who don't have erectile dysfunction are using Viagra. Why? Viagra has developed a reputation for being a male aphrodisiac, and a section of men could be using Viagra for male enhancement. Though Viagra is a prescription drug -- in the US at least -- could a man with a claim of erectile dysfunction have that claim somehow disproved? Possibly. Possibly not.

The open secret about Viagra, and some other drugs, is that it's available without having to go to one's personal physician for a prescription. Online sources, often referring to themselves as pharmacies, will either arrange for an online prescription to be obtained, or will sell Viagra without a prescription outright. There is a crackdown in place against these online drug dispensers, however, so this option for obtaining Viagra may not be the convenience it once was.

Viagra's overwhelming success has, not surprisingly, encouraged competition. There are now two other prescription drug alternatives to Viagra: Cialis and Levitra. Both of these drugs -- and Viagra -- have massive marketing campaigns that include prime time television commercials. (The fact that treatments for erectile dysfunction are now advertised on prime time television in the United States is a story in itself.)

Viagra's success has also produced competition from nonprescription products, products different from Viagra in they are designed specifically for intimacy enhancement and not erectile dysfunction. These latest competitors to Viagra are becoming increasingly popular and a new niche -- nonprescription enhancers -- is developing as a result.