Zidovudine, also known as AZT, is an antiretroviral medication used to treat HIV infection. It works by inhibiting the reverse transcriptase enzyme, which is essential for the virus to replicate. Zidovudine is often part of a combination therapy to improve its effectiveness and reduce the risk of drug resistance. Initially approved in 1987, zidovudine was the first drug approved for the treatment of HIV/AIDS. It can help lower the viral load in the body, improving the immune system's function and reducing the risk of developing AIDS or related illnesses.