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 zidovudine (ZDV, formerly AZT) and stavudine (d4T). These medicines are usually combined for best results.
• Nonnucleoside reverse transcriptase inhibitors (NNRTIs), such as efavirenz, nevirapine, or delavirdine.
• Protease inhibitors (PIs), such as atazanavir, saquinavir, ritonavir, indinavir, nelfinavir, fosamprenavir, lopinavir/ritonavir, tipranavir, or darunavir.
• Fusion inhibitors, such as enfuvirtide.
• Entry inhibitors. The only entry inhibitor approved by the U.S. Food and Drug Administration (FDA) for the treatment of HIV infection is maraviroc (Selzentry). This medicine is used with other HIV medicines for adults whose current treatments are no longer controlling virus activity.
• Integrase inhibitors. The only integrase inhibitor approved by the 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.

Other medicines that may be used to treat HIV or AIDS-related conditions include cytokines, such as interferon alfa-2a and interferon alfa-2b.

Taking antiretroviral therapy for HIV

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.