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Updated August 2022
Azathioprine (brand names: Azapin®, Imazan, Imuran®, Thioprine®) is a medicine used to treat immune and inflammatory diseases such as vasculitis, systemic lupus erythematosus (SLE/lupus), polymyositis (muscle inflammation), rheumatoid arthritis and other rheumatic and autoimmune conditions.
Azathioprine is also used to prevent the rejection of transplanted organs and to treat inflammatory bowel disease such as Crohn’s Disease or Ulcerative Colitis.
Azathioprine is an immunosuppressive medicine, which means that it works by reducing the activity of the immune system. In rheumatoid arthritis this action helps to reduce inflammation and thus reduce pain and swelling. It also limits damage to the joints and helps to prevent disability in the long term.
Because azathioprine acts to reduce the damage to the joints, rather than just relieve the pain, it belongs to the group of medicines called disease modifying antirheumatic drugs (DMARDs).
Azathioprine does not work straight away. It usually takes 6 to 8 weeks for symptoms such as swelling and stiffness to start to improve. The effects to delay or prevent joint damage will take several months to be noticed. Other medicines may be given to improve your symptoms while waiting for azathioprine to work.
If you stop your azathioprine treatment for more than a few weeks there is a risk that your condition may worsen. It is important to continue taking azathioprine even if you feel well.
Treatment with azathioprine may be continued indefinitely as long as it is effective and no serious side effects occur.
Azathioprine is taken by mouth in 25mg or 50mg tablets which should be swallowed whole. Breaking or crushing of tablets should be avoided.
The dose will depend on your particular immune or inflammatory condition, and is adjusted depending on your body weight. It is usually started at 50mg to 100mg per day. The dose can be increased every 1 to 2 months. The maximum dose can be up to 250mg per day.
Azathioprine can be taken as a once or twice daily dose.
Azathioprine may be used with most other arthritis medicines including:
There are separate information sheets for the medicines mentioned above.
You might experience side effects with your treatment. Tell your doctor if you are concerned about possible side effects.
A reduction in dose may minimise the side effects so that you can continue to take this treatment. Your doctor will advise on any dose changes that are necessary.