On this day in 1998, the Food and Drug Administration (FDA) approves use of the drug Viagra, an oral medication that treats impotence.

Sildenafil, the chemical name for Viagra, is an artificial compound that was originally synthesized and studied to treat hypertension (high blood pressure) and angina pectoris (a form of cardiovascular disease). Chemists at the Pfizer pharmaceutical company found, however, that while the drug had little effect on angina, it could induce penile erections, typically within 30 to 60 minutes. Seeing the economic opportunity in such a biochemical effect, Pfizer decided to market the drug for impotence. Sildenafil was patented in 1996, and a mere two years later–a stunningly short time compared to other drugs–it was approved by the FDA for use in treating “erectile dysfunction,” the new clinical name for impotence. Though unconfirmed, it is believed the drug was invented by Peter Dunn and Albert Wood.

Viagra’s massive success was practically instantaneous. In the first year alone, the $8-$10 pills yielded about a billion dollars in sales. Viagra’s impact on the pharmaceutical and medical industries, as well as on the public consciousness, was also enormous. Though available by prescription only, Viagra was marketed on television, famously touted by ex-presidential candidate Bob Dole, then in his mid-70s. Such direct-to-consumer marketing was practically unprecedented for prescription drugs (now, sales and marketing account for approximately 30 percent of the pharmaceutical industry’s costs, in some cases more than research and development). The drug was also offered over the internet–customers needed only to fill out an “online consultation” to receive samples.

An estimated 30 million men in the United States suffer from erectile dysfunction and a wave of new Viagra competitors, among them Cialis (tadalafil) and Levitra (vardenafil), has blown open the market. Drug companies are now not just targeting older men like Dole, but men in their 30s and 40s, too. As with many drugs, the long-term effects of Viagra on men’s health are still unclear (Viagra does carry warnings for those who suffer from heart trouble), but its popularity shows no signs of slowing. To date, over 20 million Americans have tried it, and that number is sure to increase as the baby boomer population continues to age.