Entavir (Entecavir) is an antiviral medication used to treat chronic hepatitis B virus (HBV) infection. It works by blocking the actions of the virus in your body and preventing further damage to your liver. Entavir is available in tablet form and is taken once a day. This medication can help reduce the amount of virus in your body and can help reduce the risk of serious liver problems. Entavir is a prescription medication, so talk to your doctor to find out if it’s right for you.