Viread, known generically as tenofovir disoproxil fumarate, is an antiviral medication used in the treatment of HIV (human immunodeficiency virus) and chronic hepatitis B virus (HBV) infections. It belongs to a class of drugs known as nucleotide reverse transcriptase inhibitors (NRTIs), which work by blocking the action of an enzyme called reverse transcriptase that is essential for the viruses to multiply. By inhibiting this enzyme, Viread helps to decrease the amount of virus in the body, thereby improving the immune system's ability to fight off infections. Although Viread is effective in controlling HIV and HBV, it is not a cure for these diseases and must be taken as part of a combination therapy to manage the infection effectively. Patients are advised to follow their healthcare provider's instructions closely when taking Viread to ensure its efficacy and to monitor for potential side effects.