What is HIV/AIDS?

HIV stands for human immunodeficiency virus. It harms your immune system by destroying CD4 cells. These are a type of white blood cells that fight infection. The loss of these cells makes it hard for your body to fight off infections and certain HIV-related cancers.

Without treatment, HIV can gradually destroy the immune system and advance to AIDS. AIDS stands for acquired immunodeficiency syndrome. It is the final stage of infection with HIV. Not everyone with HIV develops AIDS.

What is antiretroviral therapy (ART)?

The treatment of HIV/AIDS with medicines is called antiretroviral therapy (ART). It is recommended for everyone who has HIV. The medicines do not cure HIV infection, but they do make it a manageable chronic condition. They also reduce the risk of spreading the virus to others.

How do HIV/AIDS medicines work?

HIV/AIDS medicines reduce the amount of HIV (viral load) in your body, which helps by:

• Giving your immune system a chance to recover. Even though there is still some HIV in your body, your immune system should be strong enough to fight off infections and certain HIV-related cancers.
• Reducing the risk that you will spread HIV to others

What are the types of HIV/AIDS medicines?

There are several different types of HIV/AIDS medicines. Some work by blocking or changing enzymes that HIV needs to make copies of itself. This prevents HIV from copying itself, which reduces the amount of HIV in the body. Several medicines do this:

• Nucleoside reverse transcriptase inhibitors (NRTIs) block an enzyme called reverse transcriptase
• Non-nucleoside reverse transcriptase inhibitors (NNRTIs) bind to and later change reverse transcriptase
• Integrase inhibitors block an enzyme called integrase
• Protease inhibitors (PIs) block an enzyme called protease

Some HIV/AIDS medicines interfere with HIV's ability to infect CD4 immune system cells:

• Fusion inhibitors block HIV from entering the cells
• CCR5 antagonists and post-attachment inhibitors block different molecules on the CD4 cells. To infect a cell, HIV has to bind to two types of molecules on the cell's surface. Blocking either of these molecules prevents HIV from entering the cells.
• Attachment inhibitors bind to a specific protein on the outer surface of HIV. This prevents HIV from entering the cell.

In some cases, people take more than one medicine:

• Pharmacokinetic enhancers boost the effectiveness of certain HIV/AIDS medicines. A pharmacokinetic enhancer slows the breakdown of the other medicine. This allows that medicine to stay in the body longer at a higher concentration.
• Multidrug combinations include a combination of two or more different HIV/AIDS medicines

When do I need to start taking HIV/AIDS medicines?

It's important to start taking HIV/AIDS medicines as soon as possible after your diagnosis, especially if you:

• Are pregnant
• Have AIDS
• Have certain HIV-related illnesses and infections
• Have an early HIV infection (the first 6 months after infection with HIV)

What else do I need to know about taking HIV/AIDS medicines?

It's important to take your medicines every day, according to the instructions from your health care provider. If you miss doses or don't follow a regular schedule, your treatment may not work, and the HIV virus may become resistant to the medicines.

HIV medicines can cause side effects. Most of these side effects are manageable, but a few can be serious. Tell your health care provider about any side effects that you are having. Don't stop taking your medicine without first talking to your provider. He or she may give you tips on how to deal with the side effects. In some cases, your provider may decide to change your medicines.

What are HIV PrEP and PEP medicines?

HIV medicines are not just used for treatment. Some people take them to prevent HIV. PrEP (pre-exposure prophylaxis) is for people who don't already have HIV but are at very high risk of getting it. PEP (post-exposure prophylaxis) is for people who have possibly been exposed to HIV.

NIH: Office of AIDS Research