A once-a-day HIV treatment combining three drugs in one pill, has been licensed for the first time by the US Food and Drug Administration.
Atripla, made by Bristol-Myers-Squibb and Gilead Sciences, contains efavirenz, tenofovir and emtricitabine got fast-track approval.
It is expected to be licensed in Europe next year.
HIV experts said patients were increasingly demanding combined treatments.
Atripla contains one of the most common combinations of drugs used by patients in the US and Europe in one pill.
It is currently available as two pills - Sustiva (efavirenz) and Truvada (tenofovir and emtricitabine).
The collaboration between the two drug companies will mean patients can take one drug a day.
Merck, which holds the rights to efavirenz, has also been involved.
The number of pills people with HIV have to take each day has been reduced in recent years.
But making it as easy as possible for people to stick to their drug regimen is important; both for the patient themselves, and to prevent the emergence of drug-resistant strains of the virus which can develop when people fail to take all their medication.
However, Atripla will still be expensive, costing more than $1,000 a month.
Mike Leavitt, US Secretary of Health and Human Services, said: "This key breakthrough will help in our battle against HIV/Aids.
"I commend those involved for working together to place this lifesaving drug on the fast track so it will be available more quickly to those who need it."
Keith Alcorn, of the National Aids Manual (NAM) said: "The incentive for creating this combination treatment is that it makes it much more convenient for patients to take.
"Increasingly, patients are becoming used to taking once-daily treatments with fewer pills.
"It won't be possible for all HIV drugs to be put together because some have properties which mean they can't live together in one pill."
He added: "This is an important development.
"I would hope to see other companies doing the same thing, and collaborating more in the future."