None of the current drugs are powerful enough to fight HIV on their own. But a combination of drugs used together is strong enough prevent the virus replicating efficiently and control your HIV infection.

• When HIV drugs were first developed, people used one drug by itself. Later they used combinations of two drugs. In both these cases the benefit from treatment only lasted a few months, perhaps a year or two at the most, and resistance to the drugs developed.
• Using three or more drugs together to treat HIV suppresses the virus to very low levels and the risk of resistance to the drugs is reduced greatly.

Using three or more drugs together is called combination therapy.

Some combinations come as three drugs in one pill. It is important to remember that these single pills include three different drugs. These include:

• Atripla (tenofovir, FTC + efavirenz)

• Triomune (d4T, 3TC + nevirapine)

In recent years some researchers have looked at whether one boosted drug could be strong enough to control HIV. These are studies using a class of drugs called protease inhibitors (PIs). Some people use a protease inhibitor that is boost by another PI as combination therapy. Only some PIs can be used in this way.

In generally this is almost as good as triple therapy combinations, but it is not quite as good.