You should not take entecavir if you have HIV (human immunodeficiency virus) that is not being treated.
You may develop lactic acidosis, a dangerous build-up of lactic acid in your blood. Call your doctor or get emergency medical help if you have unusual muscle pain, trouble breathing, stomach pain, dizziness, feeling cold, or feeling very weak or tired.
Hepatitis B may become active or get worse after you stop using entecavir. You may need frequent liver function tests for several months.
Before taking this medicine
You should not take entecavir if you are allergic to it, or if you also have HIV (human immunodeficiency virus) that is not being treated.
You may need to be tested for HIV before you start taking entecavir. Taking medicine to treat chronic hepatitis B can cause HIV infection to become resistant to certain HIV and AIDS medications.
Tell your doctor if you have ever had:
HIV or AIDS (or if you have been exposed to HIV);
kidney disease;
liver problems other than HBV;
a liver transplant; or
if you also take lamivudine (Epivir, Epzicom, Trizivir) or telbivudine (Tyzeka).
Tell your doctor about all medicines you have used to treat hepatitis B in the past. Entecavir may not be the right medication if you have used certain other medicines for HBV.
You may develop lactic acidosis, a dangerous build-up of lactic acid in your blood. This may be more likely if you are overweight, if you've taken antiviral medication for a long time, or if you are a woman. Ask your doctor about your risk.
Tell your doctor if you are pregnant or breastfeeding.
If you are pregnant, your name may be listed on a pregnancy registry to track the effects of entecavir on the baby.
