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Azapress, Imuran

Azathioprine will be prescribed for you by a specialist doctor.

Swallow the tablets whole 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. It is important to protect yourself from serious illness by having any vaccinations your doctor offers you.

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About azathioprine

Type of medicine

An immunosuppressant

Used for

To prevent organ rejection following transplant operations

To treat chronic inflammatory and autoimmune conditions

Also called

Azapress®; Imuran®

Available as

Tablets, oral liquid medicine 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 long-term (chronic) 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.

Before taking azathioprine

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 breastfeeding.

  • If you have liver or kidney problems.

  • If you have any infection.

  • If you have ever had chickenpox or shingles.

  • If you have been told you have a rare, inherited metabolic disorder called Lesch-Nyhan syndrome or you have a lack of an enzyme called TPMT.

  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well 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.

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How to take azathioprine

  • 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.

  • Do not drink milk or eat dairy products (such as yoghurt) at the same time as taking your azathioprine dose. Dairy products contain an enzyme which can break down azathioprine making your treatment less effective.

  • 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.

Getting the most from your treatment

  • 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.

  • This medicine lowers your natural protection against infection. It is important to protect yourself from serious illness by having any vaccinations your doctor offers you. If you live with other people they can also help protect you by having their own vaccinations.

  • Some vaccines may not be suitable for people with lowered immune systems. Always let the person vaccinating know that you are taking this medicine.

  • It is important to try to avoid anyone who has chickenpox or shingles. Tell your doctor if you come into contact with anyone with these infections.

  • 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 or your partner 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.

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Can azathioprine cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with azathioprine. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Azathioprine side-effects

What should I do if I experience this?

Feeling extremely tired or dizzy, being sick (vomiting), loose or watery stools (diarrhoea), a high temperature (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, a sore throat 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.

How to store azathioprine

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

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.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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