Azathioprine (Imuran)

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Azathioprine will be prescribed for you by a specialist doctor.

Swallow the tablets with plenty of water, after a meal. Do not crush or break the tablets.

Azathioprine may reduce your body's resistance to infections. Try to keep away from people who you know are ill.

Type of medicine An immunosuppressant
Used for To prevent organ rejection following transplant operations
To treat chronic inflammatory and auto-immune conditions
Also called Imuran®
Available as Tablets and injection

Azathioprine is an immunosuppressant, which simply means that it suppresses your immune or defence system. It is used to help prevent rejection following organ transplant operations and also to treat a variety of chronic (long-term) inflammatory and autoimmune conditions, such as rheumatoid arthritis, systemic lupus erythematosus, and Crohn's disease.

Following organ transplant operations, it is natural for your body to try to reject the new tissue as it regards it as 'foreign'. By suppressing your defence system, azathioprine helps to prevent your body from fighting the new organ.

In chronic inflammatory and autoimmune conditions your immune system attacks part of your own body as if it were foreign. Azathioprine reduces inflammation and the symptoms it causes because it suppresses your immune system.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking azathioprine it is important that your doctor or pharmacist knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have liver or kidney problems.
  • If you have an infection.
  • If you have had chickenpox or shingles.
  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • If you have ever had an allergic reaction to a medicine. It is particularly important that you tell your doctor if you are allergic to a medicine called mercaptopurine.
  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The leaflet will give you more information about azathioprine, how to take it, and a full list of side-effects which you may experience from taking it.
  • Your doctor will prescribe a dose for you which is tailored to your weight and the reason why you are taking it. Make sure you take the tablets exactly as your doctor has told you - your dose will be on the label of the pack to remind you.
  • Take the tablets after eating a meal or with a snack. This will help to stop any feelings of queasiness or nausea. Drink plenty of water as you take the tablets.
  • Try to take your doses at the same time of day each day, as this will help you to remember to take them. If you forget to take a dose at the usual time, take one as soon as you remember, but do not take two doses together to make up for a missed dose.
  • Your doctor will tell you how long your treatment is expected to continue. Keep taking azathioprine until your doctor tells you otherwise.
  • Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress. Your doctor will want you to have regular blood tests during this treatment to monitor for unwanted side-effects.
  • It is important to try to avoid anyone who is suffering from chickenpox or shingles. Tell your doctor if you come into contact with anyone with these infections.
  • While you are taking azathioprine, and for a while after you stop treatment, do not have any immunisations (vaccinations) without talking to your doctor first. Azathioprine lowers your body's resistance and there is a chance that you may get an infection from the vaccine. Also, some vaccines may be less effective.
  • Your doctor will have discussed with you the possibility of a slightly increased risk of cancer (particularly skin cancer) associated with immunosuppressants like azathioprine. Do not use sunbeds, and avoid strong sunlight or use a sun cream with a high sun protection factor (SPF of at least 15).
  • You should avoid becoming pregnant while you are taking azathioprine. Make sure you have discussed with your doctor which types of contraception are suitable for you and your partner.
  • If you are having an operation or any dental treatment, tell the person carrying out the treatment that you are taking azathioprine.
  • If you buy any medicines, check with your doctor or a pharmacist that they are suitable for you to take with your other medicines.

Along with their useful effects, most medicines can cause side-effects although not everyone experiences them. Before you start treatment with azathioprine, your doctor will discuss with you the possibility of unwanted side-effects occurring. You should let your doctor or clinic know as soon as possible if you experience any of the following:

Azathioprine side-effects
What should I do if I experience this?
Feeling extremely tired or dizzy, being sick, diarrhoea, fever, muscle pain or stiffness, skin rash, kidney problems (such as a change in the amount or colour of your urine) These may be signs of an allergic reaction. Let your doctor know straightaway
Feeling unwell, a high temperature or symptoms of an infection Let your doctor know straightaway. This is especially important if you have been near anyone with chickenpox or shingles
Unexpected bruising or bleeding These are symptoms of bone marrow suppression. Let your doctor know about this straightaway
Loss of hair This may resolve on its own, but speak with your doctor if it becomes troublesome

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist for advice.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Further reading & references

  • Manufacturer's PIL, Imuran® Tablets; The electronic Medicines Compendium. Dated January 2012.
  • British National Formulary; 65th Edition (Mar 2013) British Medical Association and Royal Pharmaceutical Society of Great Britain, London

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Dr John Cox
Document ID:
3266 (v23)
Last Checked:
Next Review:
The Information Standard - certified member

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