PrEP helps keep gay and bisexual teens negative from HIV.

A group of gay and bisexual teenage males safely used a medication that prevents HIV infection, though some failed to follow the drug regimen fully and became infected, researchers report.

People at risk for becoming infected with the virus that causes AIDS can dramatically lower their risk of infection by taking the drug Truvada in what is known as the PrEP regimen, but its use is only approved for adults.