Treating Hepatitis B With Entecavir

Risks and Benefits

Entecavir is an antiviral drug used in the treatment of chronic hepatitis B, particularly patients with liver damage. It is sold under the brand name Baraclude by Bristol-Myers Squibb Pharmaceutical Company, although generic equivalents of the drug became available in 2014.

Paperwork with Hepatitis A and B listed
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How It Works 

Entecavir is a reverse transcriptase inhibitor that works by preventing the hepatitis B virus from multiplying and thereby decreasing the amount of the virus in the body. However, it is important to note that entecavir is not a cure for HBV and it may not prevent damage to the liver or reduce the chances of developing liver cancer. In addition, entecavir doesn't prevent the spread of HBV to others through the normal routes of transmission, including sexual contact or exposure to blood or bodily fluids.

How to Take Entecavir

Entecavir is available as a tablet (either 0.5 mg or 1 mg) or an orange-flavored solution that you drink. A standard dose is 0.5 mg once daily for one year. The dose is doubled for people who have persistent hepatitis viremia (the presence of virus in the blood) while taking lamivudine or have lamivudine resistance. It's recommended to take entecavir on an empty stomach, two hours before or after a meal.


One year of treatment with entecavir can easily cost around $9,600. However, drug costs vary considerably based on many factors, such as whether you have health insurance, where you live and which pharmacy you use.

Side Effects

As with all drugs, there are some risks to taking entecavir. Some are more serious than others.

Lactic Acidosis

In rare cases, entecavir can cause a condition known as lactic acidosis, which is a build-up of lactic acid in the body. This condition can come on insidiously and worsen over time, therefore even mild symptoms warrant seeking emergency medical help. Symptoms of lactic acidosis include:

  • Muscle pain and/or weakness
  • A numb or cold feeling in the limbs
  • Difficulty breathing
  • Feeling dizzy, light-headed, tired, or very weak
  • Stomach pain, nausea or vomiting
  • Slow or uneven heart rate

Severe Liver Disease

Entecavir can also cause severe liver symptoms in some patients. Any of the following symptoms should prompt you to call your healthcare provider or seek emergency medical care: 

  • Low fever
  • Nausea, stomach pain or loss of appetite
  • Dark urine, clay-colored stools or jaundice 

Other Side Effects

Milder and less dangerous side effects are also possible when taking entecavir. These include a headache, fatigue, dizziness, sleeplessness, rash, vomiting, temporary hair loss, and diarrhea. Also, it's important to know that if you stop taking entecavir before the end of your treatment, your hepatitis might get worse.

Who Should Not Take Entecavir

Anyone who is allergic to entecavir shouldn't take this drug. Also, it's important to know your HIV status because taking entecavir can significantly complicate treating HIV. Don't start entecavir if you have untreated or unrecognized HIV infection without seeing an infectious disease specialist.

Monitoring Liver Function

While taking entecavir, your healthcare provider will most likely want to monitor your liver function. In fact, some patients develop liver symptoms weeks or even months after they stop taking entecavir, so your liver function may be monitored regularly for several months after stopping the drug.

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3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Medline Plus. Entecavir: drug information. Revised May 2018

  2. Chang TT, Lai CL, Kew yoon S, et al. Entecavir treatment for up to 5 years in patients with hepatitis B e antigen-positive chronic hepatitis B. Hepatology. 2010;51(2):422-30. doi:10.1002/hep.23327

  3. Fontana RJ. Side effects of long-term oral antiviral therapy for hepatitis B. Hepatology. 2009;49(5 Suppl):S185-95. doi:10.1002/hep.22885

Additional Reading
  • U.S. Food and Drug Administration. Viral Hepatitis Therapies 
  • UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2010.