Tenofovir is used along with other medications to treat human immunodeficiency virus (HIV) infection in adults and children 2 years of age and older. Tenofovir is also used to treat chronic (long term) HBV in adults and children 2 years of age and older weighing 22 pounds (10 kilograms) or more. Tenofovir is in a class of medications called nucleoside reverse transcriptase inhibitors (NRTIs). It works by decreasing the amount of HIV and HBV in the blood. Although tenofovir will not cure HIV, it may decrease your chance of developing acquired immunodeficiency syndrome (AIDS) and HIV-related illnesses such as serious infections or cancer. Taking these medications along with practicing safer sex and making other lifestyle changes may decrease the risk of transmitting the HIV virus to other people. Tenofovir will not cure hepatitis B and may not prevent complications of chronic hepatitis B such as cirrhosis of the liver or liver cancer. Tenofovir may not prevent the spread of hepatitis B to other people.