Anti-HIV drugs inhibit proliferation of the virus by interfering with various phases of its life cycle. They are always used in combination therapy:

• Reverse transcriptase inhibitors (RT inhibitors) interfere with transcription of the genetic information of the virus from RNA into DNA. In this way they inhibit a process that results in the genetic material of the virus being incorporated into the genetic material of the infected cell.
• Protease inhibitors deprive the virus of proteins that it needs in order to infect new cells. Though new viral particles continue to be formed, they are unable to infect new cells.
• Fusion inhibitors prevent HIV from entering, and thus infecting, cells. Uninfected cells are protected.