Efavirenz is an antiretroviral medication used to treat HIV infection. It belongs to a class of drugs called non-nucleoside reverse transcriptase inhibitors (NNRTIs), which work by blocking the reverse transcriptase enzyme, preventing the virus from replicating in the body. Typically taken once daily, efavirenz is often combined with other antiretroviral medications to enhance its effectiveness. It may cause side effects such as dizziness, sleep disturbances, and rash, but many people tolerate it well. Regular monitoring by a healthcare provider is essential to ensure the treatment's success and manage any potential side effects.