HIV is a virus which attacks the immune system – the body’s defence system against infection and illness. If you have HIV, you can take drugs to reduce the level of HIV in your body. By reducing the amount of HIV in your body, you can slow or prevent damage to your immune system. These drugs are not a cure, but they can help you stay well and extend your life. Anti-HIV drugs are known as antiretroviral drugs.

HIV mainly infects cells in the immune system called CD4 cells. Over many years of HIV infection, the number of CD4 cells drops gradually but continually and the immune system is weakened. If nothing is done to slow or halt this destruction of the immune system, a condition called AIDS (Acquired Immune Deficiency Syndrome) follows, as the immune system is no longer able to fight infections. Antiretroviral drugs work by interrupting this process. 

An untreated person with HIV may have thousands or even millions of HIV particles in every millilitre of blood. The aim of treatment is to reduce the amount of HIV to very low levels (this is called an ‘undetectable’ level) – below 50 copies per millilitre of blood, although some HIV treatment centres are now using tests that can measure as low as 40 copies/ml. 

To provide you with the best chance of reducing the amount of HIV in your blood to very low levels, your doctor will recommend that you take a powerful combination of at least three antiretroviral drugs. Once your viral load – the amount of HIV in your blood – has dropped, your immune system should begin to recover and your ability to fight infections is likely to improve.