Truvada is the first drug approved by Food and Drug Administration to be used for HIV infection prevention.
Truvada, made by California-based Gilead Sciences, can be used by those at high risk of infection and anyone who may engage in sexual activity with HIV-infected partners, said FDA.
Studies showed the drug reduced the risk of contracting HIV by up to 73%.
Some health workers and groups active in the HIV community opposed a green light for the once-daily pill.
There have been concerns the circulation of such a drug could engender a false sense of security. There have also been fears that a drug-resistant strain of HIV could develop.
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.
In May, an advisory group of health experts recommended approval for the pill.
Truvada, is already backed by the FDA to be taken with existing anti-retroviral drugs for people who have HIV.
Studies from 2010 showed that Truvada reduced the risk of HIV in healthy gay men – and among HIV-negative heterosexual partners of HIV-positive people – by between 44% and 73%.