The Food and Drug Administration approves the drug sildenafil, commonly known as Viagra, to treat erectile dysfunction.
Viagra was discovered by three Pfizer scientists while working on ways to develop a drug to help people with high blood pressure or angina pectoris. The drug didn't help either of those conditions, but one of its side effects proved to combat erectile dysfunction.
By 2000, Viagra accounted for 92% of the erectile dysfunction drug marketplace, and by 2008 its sales approached two billion dollars a year.
Viagra is also used to treat people for high-altitude pulmonary edema caused by altitude sickness.