Entecavir is used to treat chronic (long-term) hepatitis B infection (swelling of the liver caused by a virus) in adults and children 2 years of age and older who have liver damage. Entecavir is in a class of medications called nucleoside analogs. It works by decreasing the amount of hepatitis B virus (HBV) in the body. Entecavir does not cure HBV and may not prevent complications of chronic hepatitis B such as cirrhosis of the liver or liver cancer. Entecavir does not prevent the spread of HBV to other people.

IMPORTANT WARNING:

Entecavir can cause serious or life-threatening damage to the liver and a condition called lactic acidosis (a buildup of acid in the blood). The risk that you will develop lactic acidosis may be higher if you are a woman, if you are overweight, or if you have been treated with medications for hepatitis B virus (HBV) infection for a long time. Tell your doctor if you have or have ever had liver disease. If you experience any of the following symptoms, call your doctor immediately: yellowing of the skin or eyes; dark-colored urine; light-colored bowel movements; difficulty breathing; stomach pain or swelling; nausea; vomiting; unusual muscle pain; loss of appetite for at least several days; lack of energy; extreme weakness or tiredness; feeling cold, especially in the arms or legs; dizziness or lightheadedness; or fast or irregular heartbeat.

Do not stop taking entecavir without talking to your doctor. When you stop taking entecavir, your hepatitis may get worse. This is most likely to happen during the first several months after you stop taking entecavir. Take entecavir exactly as directed. Be careful not to miss doses or run out of entecavir.If you experience any of the following symptoms after you stop taking entecavir, call your doctor immediately: extreme tiredness, weakness, nausea, vomiting, loss of appetite, yellowing of the skin or eyes, dark-colored urine, light-colored bowel movements, or muscle or joint pain.

If you have human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) that is not being treated with medications and you take entecavir, your HIV infection may become more difficult to treat. Tell your doctor if you have HIV or AIDS or if there is a chance that you have been exposed to HIV. Your doctor may test you for HIV infection before you begin treatment with entecavir and at any time during your treatment if there is a chance that you have been exposed to HIV. Entecavir will not treat HIV infection.

Keep all appointments with your doctor and the laboratory before, during, and for a few months after your treatment with entecavir. Your doctor will order certain tests to check your body's response to entecavir during this time.

Talk to your doctor about the risks of taking entecavir.