Each class of drugs works in a different way to fight the virus. When several of these drugs are taken together, they can slow down or almost stop the virus from reproducing for long periods in many HIV-infected persons. Taking these drugs together is called combination anti-HIV or antiretroviral drug therapy . These combinations are used by many people to try to keep the amount of virus in their blood so low that it cannot be detected. This is known as maximal viral suppression .
Resistance means that some of the virus stops responding to the drugs.
Resistance to antiretroviral drugs is believed to be a major reason that HIV is so hard to control. Researchers are constantly learning more about how resistance occurs and what can be done to delay its effects. You too can learn how to reduce the risk of resistance. It is important to remember, though, that resistance is not the only cause of treatment failure. Other reasons include the fact that some drugs don't work well together.