Examples: Imuran®, Azathioprine (generic)

Azathioprine is part of a group of medicines called immunosuppressants. They work by reducing the inflammatory action of your disease.For it to work well, this medicine should be taken as prescribed, even when your symptoms improve.

How do I take azathioprine?

Azathioprine should be swallowed whole and taken with or after food, however you should avoid milk or dairy products at least 1 hour before and 2 hours after. The amount you will need to take will depend on your weight and the activity of your disease, and it is usually given daily, sometimes in divided doses. It may take weeks or months for your condition to improve, therefore do not be discouraged if results are not immediate. Please note that azathioprine does not help everyone who takes it.


Can I carry on taking my other medications?

Due to the potential risk of the drug interacting with other medicines, you should inform your doctor and/or pharmacist about any medication you are currently taking, or any new medicines you have been prescribed. This includes any medications bought from the pharmacy without a prescription as well as herbal and complementary medicines (e.g St. John’s Wort). To ensure you remember everything, it may be helpful to bring a list of current medications with you when you see the doctor, nurse or pharmacist. You should also inform us if you are allergic to the substance 6-mercaptopurine or any other medication.


Which tests will I need and how often will I need them?

It is very important that you are regularly checked whilst using azathioprine. Therefore, before starting treatment an initial blood test will be carried out. A blood test is then usually needed every two weeks for six weeks, then monthly for three months and then at least every 12 weeks. This may vary depending on your condition. Your weight, blood pressure, cholesterol and blood sugar will also be checked regularly. It is your responsibility to ensure you have your blood tests on time. It is important that you do not miss these and that you do not take azathioprine unless you are having blood tests regularly.


What else do I need to be aware of before taking azathioprine?

Previous medical issues

Before starting azathioprine, you must inform your doctor if you have/had any kidney problems, liver problems or severe bone marrow disease. We also need to be aware if you have Lesch – Nyhan syndrome, TPMT deficiency or an inflamed pancreas. You should also inform us if you have an uncontrolled infection or a tendency to catch infections easily.


Pregnancy, contraception and breast-feeding

Due to a potential risk to the foetus, patients of child-bearing potential should use effective contraception whilst on azathioprine and for three months after stopping the drug. Azathioprine may interfere with the effectiveness of intrauterine contraceptive devices (IUCDs), so extra contraceptive measures are recommended. Please inform your doctor as soon as possible if you plan to become pregnant or think that you may be pregnant.

Azathioprine passes into breast milk, therefore please inform your doctor if you are breast-feeding and on treatment. You may be advised to stop breast-feeding while on treatment.


Viral infections and vaccinations

Your body’s resistance to infection can be reduced while you are taking azathioprine. Therefore you should avoid close contact with people who have viral infections, in particular chicken pox or shingles. If you develop either of these, you should inform your doctor immediately. You should also ask your doctor or pharmacist before having any vaccinations.

You may also be more at risk of catching infections of the skin, mouth, stomach and intestines, lungs and urinary tract. Please inform your doctor about any symptoms of infection which last for more than three days (for example, sore throat, cough, fever).


Food preparation

There are some reports of bacteria (germs) found in food that may cause a problem to those who are less able to fight infections. Your body’s resistance to infection can be reduced while you are taking azathioprine. Meat should be cooked thoroughly, and raw seafood such as oysters and sushi should be avoided. Ensure salads are washed well with hot water and avoid ready-prepared supermarket salads. Do not consume unpasteurized dairy products e.g. brie, camembert.



Azathioprine may also affect your performance of skilled tasks (e.g. driving). Avoid driving if you find you are affected.



Both alcohol and azathioprine can affect your liver. You are advised not to drink more than 14 units of alcohol per week, spread evenly over three or more days, on a regular basis. 14 units is equivalent to six pints of average-strength beer or 10 small glasses of low-strength wine.


Sun exposure

Take care to avoid too much sun (including sunbeds) whilst taking this medicine and use a sunscreen with a high protection factor e.g. SPF 50.


What are the side effects?

As with most medicines, azathioprine may cause side-effects, although this is not the case for everyone.


Possible side-effects include:

  • General tiredness.
  • Headaches and dizziness.
  • Shortness of breath when exercising.
  • Inflammation of the lungs.
  • Hair loss.
  • Pale skin and itchiness and yellowing of the skin and eyes.
  • Gastrointestinal symptoms including pale stools.
  • Increased sensitivity to sunlight and risk of skin cancer.


If you experience any of the following, you should stop taking azathioprine and seek medical advice immediately: sudden worsening of general health, such as:

  • Stomach pain with nausea and vomiting fever.
  • Shivering and chills; pain in muscles and joints.
  • Change in colour and amount of urine
  • Tiredness and dizziness.
  • Confusion, light-headedness and weakness.
  • Bruising and unusual bleeding.
  • Bumps on your body.
  • Changes in the skin (i.e. blisters or peeling).
  • Contact with anyone suffering from chickenpox or shingles.


Need more information?

Please refer to the leaflet included with the medicine for further information, or contact the pharmacy department on: 020 7566 2362