Gilead Sciences, who developed the drug, says 88 to 90 percent of patients taking it had an undetectable level of HIV in their blood after 48 weeks.
The pill contains two previously approved antiviral drugs, emtricitabine and tenofovir disoproxil fumarate, currently sold as the combination pill Truvada. Those drugs are combined with two new drugs: elvitegravir and cobicistat. Elvitegravir interferes with one of the enzymes that HIV needs to multiply. Cobicistat helps prolong the effect of elvitegravir.
Stribild will carry a warning about potentially dangerous side effects, including severe liver problems and the buildup of lactic acid.
An estimated 1.2 million Americans have HIV, which develops into AIDS unless treated with antiviral drugs. AIDS causes the body's immune system to break down, leading to infections which are eventually fatal.
The Associated Press contributed to this report.