Gilead Sciences Inc. has marketed Truvada since 2004 as a treatment for people who are already infected with the virus.
But starting in 2010, studies showed that the drug could actually prevent people from contracting HIV when used as a precautionary measure. A three-year study found that daily doses cut the risk of infection in healthy gay and bisexual men by 42 percent, when accompanied by condoms and counseling.
Last year another study found that Truvada reduced infection by 75 percent in heterosexual couples in which one partner was infected with HIV and the other was not.
Because Truvada is on the market to manage HIV, some doctors already prescribe it as a preventive measure. FDA approval will allow Gilead Sciences to formally market the drug for that use, which could dramatically increase prescribing.
Truvada's groundbreaking preventive ability has exposed disagreements about managing the disease among those in the HIV community. Groups including the AIDS Healthcare Foundation asked the FDA to reject the new indication, saying it could give patients a false sense of security and reduce the use of condoms, the most reliable preventive measure against HIV.
Michael Weinstein, president of the Los Angeles-based AIDS Healthcare Foundation, the nation's largest HIV/AIDS nonprofit medical provider, said the approval without a requirement for HIV testing "is completely reckless."
"The FDA's move today is negligence bordering the equivalence of malpractice which will sadly result in new infections, drug resistance and serious side effects among many, many people," Weinstein said in a statement.
But FDA scientists said Monday said there was no indication from clinical trials that Truvada users were more likely to engage in risky sexual behavior.
"What we found was that condom use increased over time and sexually transmitted infections either remained at baseline levels or decreased," said Debra Birnkrant, the FDA's director of antiviral products. "So, in essence, we don't have any strong evidence that condoms were not used or there was a decrease in condom use."
Gilead said it will provide vouchers for free HIV testing and condoms. As part of the risk mitigation strategy required by the FDA, Gilead said it will include information about the importance of strict adherence to the dosing regimen and emphasize that Truvada is part of a comprehensive prevention strategy and should be used only by those who are confirmed HIV negative.
This article includes information from the Bloomberg News Service.