The drug,'Truvada' can now be used by those at high risk of the infection and anyone who may engage in sexual activity with HIV-infected partners, the Food and Drug Administration (FDA) announced.
"In two large clinical trials, daily use of the drug was shown to significantly reduce the risk of HIV infection," it said yesterday.
However, some health workers and groups active in the HIV community opposed the approval for the once-a-day pill.
There are concerns that circulation of such a drug could engender a false sense of security and mean people will take more risks. There have also been fears that a drug-resistant strain of HIV could develop.
People diagnosed with HIV that without treatment develops into AIDS take antiviral medications to control the infection that attacks their immune system.
In a statement, the FDA stressed that the drug should be used as part of a "comprehensive HIV prevention plan", including condom use and regular HIV testing.
More From This Section
An advisory group of health experts recommended approval for the pill in May this year.
Truvada, is already backed by the FDA to be taken with existing antiretroviral drugs for people who have HIV.
Studies have shown that Truvada reduced the risk of HIV in healthy gay men - and among HIV-negative heterosexual partners of HIV-positive people - by between 44 per cent and 73 per cent.
"In the 80s and early 90s, HIV was viewed as a life-threatening disease; in some parts of the world it still is. Medical advances, along with the availability of close to 30 approved individual HIV drugs, have enabled us to treat it as a chronic disease most of the time," Debra Birnkrant, director of the Division of Antiviral Products at FDA, said.
"But it is still better to prevent HIV than to treat a life-long infection of HIV," she said.
Studies have shown the drug manufactured by a California-based company can reduce the risk of contracting Human immunodeficiency virus (HIV).
About 1.2 million Americans have HIV. The body