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Patient information A-Z

Who is the leaflet for?

This leaflet is for patients starting on treatment with entecavir for hepatitis B infection to provide an overview of treatment and important information.

About entecavir

What is entecavir for and how do I take it?

Entecavir is an antiviral medication used to treat long-term hepatitis B virus infection, which can cause inflammation and damage to the liver. Entecavir reduces the amount of hepatitis B virus in your body to limit damage to your liver. It is a tablet which should be taken by mouth. Your doctor or liver nurse specialist will advise you of your specific dose based on your individual treatment history, liver disease stage and kidney function but it is commonly taken once a day.

In most cases, entecavir can be taken with or without food. However, if you were switched to entecavir due to treatment failure with lamivudine, you should take entecavir on an empty stomach. If your liver disease is very advanced, you should also take entecavir on an empty stomach. 'Empty stomach' means at least two hours before or two hours after eating.

Entecavir is usually continued long-term. Do not stop taking entecavir without discussion with your doctor or liver nurse specialist. Your hepatitis B virus infection may get worse if you stop taking entecavir.

Are there any problems with taking entecavir?

Broadly, entecavir is safe and well tolerated, but you should be aware of the following potential issues.

Side effects

The most common side effects from entecavir include headache, tiredness, sleepiness, dizziness, difficulties sleeping, nausea, vomiting, diarrhoea, indigestion.

Increased blood levels of liver enzymes: contact your doctor or liver nurse specialist if you experience new signs or symptoms of liver problems for example skin or white part of your eye turning yellow, dark urine, nausea, abdominal pain, lack of appetite.

Lactic acidosis (build-up of acid in the blood): a rare but serious side effect that must be treated in hospital. Contact your doctor or liver nurse specialist immediately if you experience severe abdominal pain with nausea and vomiting.

If you experience any side effects, please contact your doctor, pharmacist or liver nurse specialist. This includes any possible side effects not listed above.

Blood tests will need to be taken regularly whilst taking entecavir to monitor your liver and kidney function; your liver nurse specialist will discuss this with you. Should you become very unwell soon after starting the medication, please contact your doctor or liver nurse specialist.

Missed doses

To prevent viral mutation and liver damage, it is very important that you do not miss doses of entecavir. If you do miss a dose, but remember within twelve hours since you should have taken your dose then take your usual dose. If it has been more than twelve hours then skip the missed dose, but take your next dose when it is due. Do not take a double dose to make up for a missed dose.


Do not start entecavir if you are pregnant. Should you wish to plan a pregnancy on entecavir, this should be discussed carefully with your doctor first.

If you or your partner is of childbearing age, it is important that you take precautions to prevent pregnancy with effective contraception whilst you are on treatment and for at least six weeks after you stop treatment.


Breastfeeding mothers should stop breastfeeding whilst on entecavir.

Additional information

Only take medicines prescribed for you by your doctor and check with your doctor, liver nurse specialist or pharmacist before taking any new medicines. This includes medicines initiated by your GP or medicines/ remedies bought over the counter.

If you also have HIV infection, make sure you tell your doctor or liver nurse specialist. You should not take entecavir tablets to treat your hepatitis B infection unless you are taking medicines for HIV at the same time, as the effectiveness of future HIV treatment may be reduced. Entecavir tablets are not recommended to control HIV infection.

Can I spread hepatitis B whilst I am on treatment?

Treatment with entecavir for hepatitis B does not stop you from passing the infection on, for example through sexual contact or bodily fluids including blood, so make sure that you continue to take appropriate preventative measures. These can be discussed in more detail with your doctor or liver nurse specialist.

Further information

Further information about your tablet can be found in the patient information leaflet found in the tablet/ capsule box or on the container.

Further information on hepatitis B can be found on the following websites:

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Other formats

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Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151