Medicines are the primary treatment for HIV. Your doctor will usually prescribe several medicines-this is sometimes called an anti-HIV "cocktail"-that keeps HIV from multiplying and helps keep the immune system healthy. In the past a person had to take several doses of HIV medicine every day, which was difficult for some people. But over the past few years this routine has become much simpler, and many people take their medicine for HIV only once or twice a day.

Medicines used to treat HIV are called antiretrovirals, and several of these are combined for treatment called highly active antiretroviral therapy, or HAART. Using HAART reduces your risk of developing resistance to HIV medicines. Resistance is more likely to develop in people who are treated with only one antiretroviral medicine.

When choosing antiretroviral medicines, your doctor will consider certain factors, such as:

• The medicines' effectiveness in reducing viral load.
• The likelihood that the virus will become resistant to a certain class of medicine. If you have already been treated with a certain antiretroviral medicine, you or your doctor may already know whether you have a resistance to medicines in that class.
• Medicine side effects and your willingness to tolerate them.
• The cost of treatment with medicines.

Medicines also are used to prevent other illnesses that can occur with HIV as the result of a weakened immune system. Certain opportunistic infections, such as some types of pneumonia, can develop when HIV attacks and destroys too many CD4+ cells. If too many CD4+ cells are destroyed, the body can no longer fight off infection.

Medication Choices

Antiretroviral therapy

Medicines that prevent HIV from multiplying are called antiretrovirals and include:

• Nucleoside/nucleotide reverse transcriptase inhibitors, such as tenofovir, emtricitabine, lamivudine, and abacavir. These medicines are usually combined for best results.
• Nonnucleoside reverse transcriptase inhibitors (NNRTIs), such as efavirenz, nevirapine, or etravirine.
• Protease inhibitors (PIs), such as atazanavir, saquinavir, ritonavir, indinavir, nelfinavir, fosamprenavir, lopinavir/ritonavir, tipranavir, or darunavir.
• Fusion and entry inhibitors, such as enfuvirtide and maraviroc.
• Integrase inhibitors. The only integrase inhibitor approved by the U.S. Food and Drug Administration (FDA) for HIV treatment is raltegravir (Isentress). This medicine also is used with other HIV medicines for adults whose current treatments are no longer controlling virus activity.

HIV: Taking antiretroviral therapy

Treatment failure

If your viral load does not drop as expected, or if your CD4+ cell count starts to fall, your doctor will try to determine why the treatment was not effective.

There are two main reasons that treatment fails:

• The virus that causes HIV has become resistant. The medicine no longer effectively controls virus multiplication nor protects your immune system. Tests can determine whether resistance has occurred. You may need a different combination of medicines.
• You did not take your medicine as prescribed. If you have difficulty taking the medicines exactly as prescribed, talk with your doctor.

What To Think About