List of products in the National Drug Code with proprietary name . See also Warning section. Entecavir is used to treat long-term hepatitis B infection. Hepatitis B is an infection of the liver caused by the hepatitis B virus. Long-term infection can cause liver damage, rarely liver cancer, and liver failure. Entecavir helps to decrease the amount of hepatitis B virus in your body. It is unknown if this medication lowers your chance of getting liver cancer or liver damage. Entecavir is an antiviral that belongs to a class of drugs known as hepatitis B virus nucleoside reverse transcriptase inhibitors. Entecavir is not a cure for hepatitis B. It does not prevent the spread of the virus to others through sexual contact or blood/body fluid contamination (such as sharing used needles).