HIV needs several chemicals to make copies of itself. To control the virus, HIV medicines keep these chemicals from doing their jobs. The medicines work best in teams. So everyone who takes HIV medicines should take at least 3 different medicines. This group (combination) of medicines is called highly active antiretroviral therapy (HAART).

Types of HIV medicines

Some types of HIV medicines work on chemicals that are inside CD4 cells where the virus makes copies of itself. There are 4 types of these medicines:

Nucleoside reverse transcriptase inhibitors (NRTIs) and
non-nucleoside reverse transcriptase inhibitors (NNRTIs)
- NRTIs and NNRTIs slow down the chemical reverse transcriptase in 2 different ways. Without this chemical, HIV cannot make new copies of itself
Integrase inhibitors
- Integrase inhibitors slow integrase, the chemical HIV needs to unlock the command center of the CD4 cell. If HIV cannot get into the command center, it cannot change the cell’s instructions and tell the cell to start making virus parts
Protease inhibitors (PIs)
- PIs stop protease, the chemical HIV uses to assemble the new virus parts into finished copies of HIV. When protease is stopped, the virus parts are put together wrong. They are bad copies of the virus. They cannot infect healthy CD4 cells

Other kinds of HIV medicines work outside CD4 cells. These medicines are called entry inhibitors. They make it very hard for HIV to enter the cells. There are 2 kinds of entry inhibitors:

CCR5 Inhibitors
- HIV uses a chemical called CCR5 to recognize which cells are CD4 cells. CCR5 inhibitors stop HIV from using this chemical to find CD4 cells. If HIV cannot find CD4 cells, then HIV cannot get inside them to make copies of itself
Fusion Inhibitors (FIs)
- FIs physically block HIV from getting inside CD4 cells. If HIV cannot get inside, it cannot make copies of itself

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