What is entecavir?
Entecavir is an antiviral medicine that is used to treat chronic hepatitis B virus (HBV) in adults and children who are at least 2 years old and weigh at least 22 pounds (10 kilograms).
Entecavir is not a cure for hepatitis. It is not known whether entecavir will prevent cirrhosis or liver cancer.
Entecavir may also be used for purposes not listed in this medication guide.
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);
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.
How should I take entecavir?
Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.
Take entecavir on an empty stomach, at least 2 hours before or 2 hours after eating.
Measure liquid medicine carefully, using the dosing syringe with your medicine (not a kitchen spoon). Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you do not understand these instructions.
Entecavir doses are based on weight (especially in children and teenagers). Your dose needs may change if you gain or lose weight.
Use entecavir regularly to get the most benefit and to keep your condition from getting worse. Call your doctor if your hepatitis symptoms do not improve, or if they get worse.
Do not change your dose or dosing schedule without your doctor’s advice. Every person with HBV should remain under the care of a doctor.
Store entecavir at room temperature away from moisture, heat, and light. Keep the bottle tightly closed when not in use.
Keep the bottle of oral liquid in its original carton. Throw away any unused entecavir oral liquid after the expiration date on the label has passed.
Hepatitis B may become active or get worse in the months after you stop using entecavir. You may need frequent liver function tests while using entecavir and for several months after your last dose.
What should I avoid while taking entecavir?
Using entecavir will not prevent your disease from spreading. Do not have unprotected sex or share razors or toothbrushes. Talk with your doctor about safe ways to prevent HBV transmission during sex. Sharing drug or medicine needles is never safe, even for a healthy person.
Entecavir side effects
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Some people using entecavir develop lactic acidosis, which can be fatal. Get emergency medical help if you have even mild symptoms such as:
unusual muscle pain;
feeling dizzy, light-headed, tired, or very weak;
stomach pain, vomiting; or
fast or irregular heartbeats.
Entecavir may also cause severe liver symptoms. Call your doctor at once if you have: swelling around your midsection, nausea, stomach pain, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).
Common side effects may include:
dizziness, tired feeling; or
This is not a complete list of side effects and others may occur.
What other drugs will affect entecavir?
Other drugs may affect entecavir, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.