Overview

This information is for people who have been tested for the hepatitis B virus (HBV) and the results show that they have had the infection in the past.

HBV is an infection that affects the liver and is carried through the body in your blood and body fluids. 

Usually, once the HBV infection has ended, the body develops immunity to protect it from the virus.  

For people who need treatment that suppresses the immune system, there is a risk that the HBV infection can return. This is called HBV reactivation, and it can damage the liver. 

HBV reactivation can be prevented with antiviral medicine called entecavir. It works by stopping the virus from spreading in the liver, and is very effective when taken regularly.

Before taking entecavir

We need to take blood tests to look for past HBV infection, and to exclude other viral infections. 

Blood tests include:

• full blood count
• liver function 
• kidney function

Before starting entecavir, you should tell us if you're pregnant or planning to become pregnant.

How to take entecavir

Entecavir is a tablet taken one time each day, every day, by mouth (orally) and can be taken with or without food.

The length of time that you'll need to take entecavir depends on your immune suppressive treatment plan. 

When your immune suppressive treatment has finished, you'll need to continue taking entecavir for a while. 

If you need to have immune suppressive treatment permanently, you'll also need to take entecavir permanently. 

Your healthcare professional will tell you how long you need to continue taking entecavir. 

Regular blood tests

We take blood tests 1 month after starting entecavir. After that, we'll monitor you and take blood tests every 3 to 6 months. 

Tests include:

• hepatitis B status
• full blood count
• liver function
• kidney function

Monitoring blood tests are essential. If these are not done, your prescription might be withheld until you have your blood test.

It's important that all medicines are kept out of the reach of children. 

Taking entecavir with other medicines

Entecavir can interact with other medicines.

Before you start taking entecavir, please let your doctor know about all of the medicines you take. This should include anything prescribed for you, and any medicines you buy from a shop or pharmacy (including and herbal or homeopathic remedies).

When you have started treatment, you should always check with your doctor or pharmacist before starting any new medicines. 

If you forget to take a dose

If you forget to take your entecavir at your usual time, take it as soon as you remember. 

If you do not remember until the next day, leave out the missed dose.

Never take a double dose to make up for one you have forgotten.

Pregnancy and breastfeeding

Do not take entecavir if you're pregnant.

If you want to plan a pregnancy while taking entecavir, this should be discussed carefully with your doctor first. 

It's important that you tell us if you're pregnant or planning on getting pregnant so that we can review all of your medicines and monitor you more closely. We may suggest using an alternative medicine. 

If you need to, use 2 reliable forms of contraception while taking entecavir to minimise the risk of unintended pregnancy. 

Do not breastfeed while taking entecavir without first discussing with your doctor or medical team.

Drinking alcohol

We recommend you keep well within the national recommended limits of alcohol (maximum of 14 units per week).

14 units is about the same as 6 pints of average-strength beer or 10 small glasses of lower-strength wine.

Any amount of alcohol can damage the liver, especially if you have an underlying condition. Depending on the state of your liver, your clinician may ask you to avoid alcohol completely.

Read the NHS information about calculating alcohol units

Side effects

Most people who take entecavir tolerate it well. More information about side effects can be found in the manufacturer’s patient information leaflet that comes with the medicine. 

Possible side effects include:

• headache
• dizziness
• fatigue
• trouble sleeping (insomnia)
• feeling sick (nausea)
• being sick (vomiting)
• diarrhoea
• indigestion
• rash
• hair loss (alopecia) 
• abnormal liver tests

The side effects may reduce over time but please talk to your doctor or nurse if you have any questions about them or if they are troubling you.

Repeat prescription

Entecavir can only be prescribed by a healthcare professional at the hospital. 

If you're running out of your supply, contact the team that prescribes your immune suppressive treatment to arrange another prescription.