Famvir, manufactured by Novartis Pharmaceuticals Corp., can be taken in 1,000 milligrams doses twice daily for one day.
The Centers for Disease Control and Prevention says at least 45 million people age 12 and older in the U.S. have had a genital herpes infection.
Prior to the FDA's approval, genital herpes required five days of Famvir treatment at a lower dose.
Famvir was not FDA approved for cold sores in people without AIDS.
Now, treatment with Famir is shortened to a single day at the start of an outbreak.
The drug does not cure genital herpes or cold sores. There is no known cure for the recurring disease. Antiviral drugs such as Famvir, Zovirax and Valtrex can be used to help suppress the infection.
