Azathioprine
A DRUG Information Sheet
Why am I being prescribed azathioprine?
Azathioprine is used in the treatment of several different types of rheumatic disease, including rheumatoid arthritis and systemic lupus erythematosus (SLE). Azathioprine has effects on the immune system (the body's own defence system). One of its actions is to reduce the activity of the immune system, so it is always used with care. Doctors may prescribe it for people on steroid treatment so their steroid dose can be smaller.
When do I take azathioprine?
Azathioprine is taken either once or twice a day, with or after food.
What dose do I take?
Your doctor will advise you. Usually you will start on a low dose (e.g. 50 mg per day) and your doctor may increase this if necessary. The dose you are given will depend on your body weight.
How long will azathioprine take to work?
Azathioprine does not work immediately. It may be 6–12 weeks before you notice any benefit.
What are the possible risks or side-effects?
Sometimes azathioprine can cause sickness, diarrhoea, skin rashes, loss of appetite or hair loss. Taking azathioprine can make you more likely to develop infections. If you develop a sore throat or other infection, or if you have a fever, develop unexplained bruising or bleeding, or become jaundiced, or if you develop any other new symptoms after starting azathioprine, you should tell your doctor or rheumatology nurse specialist straight away. If any of these symptoms are severe, you should stop azathioprine and see your doctor immediately.
There is a slightly increased risk of certain types of cancer with azathioprine. Discuss this with your doctor.
If you have not had chickenpox but come into contact with someone who has chickenpox or shingles, or if you develop chickenpox or shingles, you should stop azathioprine and see your doctor immediately as you may need special treatment. This is because chickenpox and shingles can be severe in people on treatment such as azathioprine which has effects on the immune system. Therefore you may require antiviral treatment.
What other treatments could be used instead of azathioprine?
A number of other drugs are used in the treatment of rheumatoid arthritis and related conditions (see arc leaflet 'Drugs and Arthritis'). Your doctor will discuss these other options with you.
Do I need any special checks while on azathioprine?
Because azathioprine can affect the blood count (one of the effects is that fewer blood cells are made) and can sometimes cause liver problems, your doctor will arrange for you to have a blood test before you start treatment and then regular blood checks while on azathioprine. This is very important. You may be asked to keep a record booklet with your blood test results. Bring this with you when you visit your GP or the hospital. You must not take azathioprine unless you are having regular checks.
May I take other medicines along with azathioprine?
Azathioprine may be prescribed along with other drugs in treating your condition. Some drugs interact with azathioprine (e.g. allopurinol, used in the treatment of gout), so you should discuss any new medications with your doctor before starting them, and you should always tell any other doctor treating you that you are taking azathioprine.
Azathioprine is not a painkiller. If you are already on a non-steroidal anti-inflammatory drug (NSAID) or painkillers you may carry on taking these as well as azathioprine, unless your doctor advises otherwise.
Do not take over-the-counter preparations or herbal remedies without discussing this first with your doctor, rheumatology nurse or pharmacist.
Can I have immunisations while on azathioprine?
It is recommended that you should not be immunised with 'live' vaccines such as yellow fever. However, in certain situations a live vaccine may be necessary (for example rubella immunisation in women of childbearing age), in which case your doctor will discuss the possible risks and benefits of the immunisation with you.
Pneumovax and yearly flu vaccines are safe and recommended.
May I drink alcohol while taking azathioprine?
If you drink alcohol you should only drink it in moderation because azathioprine can affect the liver.
Does azathioprine affect pregnancy?
You should not normally take azathioprine when pregnant. If you are planning a family or become pregnant while taking azathioprine, you should discuss this with your doctor as soon as possible.
What about breastfeeding?
You should not breastfeed if you are taking azathioprine.
Where can I obtain further information?
If you would like any further information about azathioprine, or if you have any concerns about your treatment, you should discuss this with your doctor, rheumatology nurse or pharmacist.
Remember to keep all medicines out of reach of children.
PLEASE NOTE: We have made every effort to ensure that the content of this information sheet is correct at time of going to press, but remember that information about drugs may change. This sheet does not list all the uses and side-effects associated with this drug. For full details please see the drug information leaflet which comes with your medicine. Your doctor will assess your medical circumstances and draw your attention to any information or side-effects which may be relevant in your particular case.
