Tenofovir alafenamide (TAF) is an antiviral medication primarily used to treat HIV and hepatitis B. It works by inhibiting the reverse transcriptase enzyme, which is essential for the replication of these viruses. TAF is a prodrug of tenofovir, meaning it is converted into its active form in the body, allowing for lower doses and reduced side effects compared to older formulations. TAF is often combined with other antiretroviral drugs in treatment regimens for HIV, enhancing its effectiveness. It is taken orally, usually once daily, and is well-tolerated by most patients. Regular monitoring is recommended to assess kidney function and overall health during treatment.