The U.S. Food and Drug Administration (FDA) on Monday approved Truvada, the first drug approved to reduce the risk of HIV infection in uninfected individuals who are at high risk of infection and who may engage in sexual activity with HIV-infected partners.

The daily pill Truvada, made by California-based Gilead Sciences, combines two medicines that inhibit the reproduction of HIV. It's supposed to be used in combination with safe-sex practices to reduce infection risk.

"Truvada alone shouldn't be used to prevent HIV infection," FDA 's Dr. Debra Birnkrant, said in a media briefing.

The FDA previously approved Truvada to be used in combination with other antiretroviral agents for the treatment of HIV-infected adults and children 12 years or older.

People taking Truvada should be tested for HIV infection every three months, so treatment could begin promptly if an infection has occurred, according to the FDA.

"Today's approval marks an important milestone in our fight against HIV," said FDA Commissioner Margaret Hamburg in a statement. "Every year, about 50,000 U.S. adults and adolescents are diagnosed with HIV infection ... New treatments as well as prevention methods are needed to fight the HIV epidemic in this country."