Azathioprine medicine for autoimmune hepatitis

Autoimmune hepatitis (AIH) is a long-term liver condition, usually lifelong.

Autoimmune means your body’s immune system (the body’s defence against illness) attacks your body’s own cells.

Azathioprine is a medicine that helps to treat this condition. It suppresses the body’s immune system to treat inflammation.

Azathioprine acts slowly so it may be up to 3 months before its benefits are seen.

The length of treatment depends on each person but it is likely to be for several years and longer in some cases. Many patients need to continue treatment long term to keep their disease under control.

Before you start the medicine

You will need a few blood tests to make sure it's safe for you to start taking the medicine. These may include tests to check:

  • your blood count
  • liver and kidney function
  • TPMT, to measure the amount of enzyme you have in your blood that breaks down azathioprine
  • hepatitis B 
  • hepatitis C
  • Epstein-Barr virus, which causes glandular fever
  • HIV
  • chickenpox

We strongly recommend you have the vaccine against strains of pneumonia.

You should also have the flu vaccine every year while taking the medicine.

Your GP practice can arrange these for you.

How to take the medicine

The dose depends on your weight. Typically doses vary between 25mg and 200mg daily. This might be changed during the course of your treatment.

Azathioprine is usually available as 25mg and 50mg tablets.

You should take each dose with or immediately after food to help reduce stomach upset. The medicine should be swallowed whole with a glass of water.

Normally people take the medicine in the morning but taking it before going to bed can help if you are having problems with feeling sick.

In most cases the full dose is taken all at the same time but in some cases we may recommend splitting the dose throughout the day.

If you forget to take azathioprine

If you remember within 12 hours of your dose being due, take your dose as normal.

If it's more than 12 hours, then take the next dose as planned. Do not double your dose if you have forgotten.

Try not to forget any doses. Azathioprine works slowly and therefore if you regularly forget the medication this will result in you having a lower level in your blood, potentially making it less effective.

Regular blood tests

When you first start azathioprine, you will need regular blood tests every few weeks.

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

If your blood tests are stable after 3 months of treatment then you could continue to have them checked every 3 months with your GP. 

When you first start the medicine our specialist doctors and pharmacists monitor you for side effects or abnormalities on your blood tests. You should expect to have regular appointments or phone calls from them. 

We also monitor the levels of azathioprine in your blood, and may adjust your dose depending on the results.

Side effects of azathioprine

Azathioprine works by suppressing your immune system. This means you might be more likely to get an infection. Contact your GP if you begin to feel unwell and think you might have caught an infection.

Everyone responds differently to the medication but possible side effects include:

  • feeling sick (nausea), especially at the start of treatment. We may need to make changes to how and when you take the medication
  • flu-like symptoms including headache, muscle ache and feeling generally unwell. You might feel like this at the beginning of treatment but this often goes away within a few weeks
  • headache
  • diarrhoea
  • dizziness
  • hair loss, although this can often get better while you continue treatment
  • rashes

More serious side effects

More serious side effects will require closer monitoring and in some cases, we may decide to stop the medicine.

Pancreatitis (inflammation of the pancreas) happens in about 1 in 30 people. 

Signs of the following side effects will be monitored on your regular blood tests.

  • The medicine can suppress your bone marrow which reduces the number of red cells, white cells and platelets produced. 
  • Serious infection needing treatment such as antibiotics.
  • Abnormal liver function tests can happen in about 1 in 20 people. 

Call a GP, our team or 111 straight away if:

  • you notice any unexplained signs of bruising or bleeding 
  • you have a high temperature (fever)
  • you notice jaundice (yellowing of the eyes or skin) 
  • you have severe upper stomach pain
  • you notice a rash after starting the medicine

Go straight to the emergency department (A&E) if you feel very unwell.

Azathioprine increases the skin’s sensitivity to the sun and so increases the risk of certain types of skin cancer. Wear protective clothing and use a high sun protection factor (SPF 50) sun cream.

Lymphoma is a type of cancer affecting the lymph glands. The risk of getting this is higher than in the general population but it remains very rare (1 in 2,500 people).

Taking azathioprine with other medicines

Azathioprine can interact with other medicines.

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

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

A medicine used for the treatment of gout, called allopurinol, interacts with azathioprine so they should not usually be taken together. However, in some cases allopurinol will deliberately be prescribed by your specialist team, to be used with a low dose of azathioprine, if you are experiencing lots of side effects or abnormal blood tests with azathioprine.

Other medicines such as co-trimoxazole, trimethoprim and warfarin can also interact with azathioprine.

You should ideally avoid ‘live’ vaccines when you are taking azathioprine and for at least 3 months after stopping it. If you are considering having vaccinations check with your doctor or pharmacist first.

Drinking alcohol while taking azathioprine

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 such as autoimmune hepatitis. Depending on the state of your liver, your clinician may ask you to avoid alcohol completely.

Pregnancy and breastfeeding

The most important thing is that your AIH is as controlled as well as possible during pregnancy.

It's important you tell us if you are pregnant or planning on getting pregnant so that we can review all of your medicines and monitor you more closely.

Our team will be able to discuss the risks and benefits of continuing azathioprine during pregnancy. Many people continue to take azathioprine safely throughout their pregnancy.

Getting a repeat prescription

After your hospital specialist has started you on azathioprine, they'll advise your GP what dose to prescribe.

Your first prescriptions will be given to you by the hospital until your GP has agreed to prescribe them to you. If your GP does not agree to prescribe your azathioprine, your prescriptions will continue to be supplied from our hospital

If any changes to the dose are needed then the hospital will tell your GP.

Useful information

For more information about autoimmune hepatitis please visit the British Liver Trust or call the helpline number on 0800 652 7330.

Resource number: 5077/VER2
Last reviewed: October 2020
Next review due: October 2023

Trusted Information Creator. Patient Information Forum

Contact us

If you have any questions or concerns about azathioprine, please call the hepatology team on 020 7188 2492

You can also email the liver team on [email protected]

For questions specifically about your medicine, email the pharmacy team on [email protected]

Please leave your name, date of birth, hospital number and details of your enquiry. Queries will be responded to 9am to 5pm, Monday to Friday.

If you are concerned outside these hours, please contact your GP or call NHS 111.

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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