US health regulators have for the first time approved a drug to prevent HIV infection.
Truvada can be used by those at high risk of infection and anyone who may engage in sexual activity with HIV-infected partners, said the Food and Drug Administration (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, made by California-based Gilead Sciences, 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%.