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Crohn's Disease Health Center

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Immunomodulators for Inflammatory Bowel Disease


Generic Name Brand Name
azathioprine Azasan, Imuran
mercaptopurine Purinethol
methotrexate Trexall

How It Works

Immunomodulator medicines weaken or suppress the immune system.

Why It Is Used

Immunomodulators are used for inflammatory bowel disease (IBD) that:

  • Has not responded to other treatments.
  • Can be controlled only with long-term use of corticosteroids. Immunomodulators may be used so that the doctor can lower the dose of corticosteroids that a person is taking. This is called "steroid sparing."

How Well It Works

Crohn's disease

Azathioprine and mercaptopurine work to keep people who have Crohn's disease in remission. They are also used to allow the person to stop using corticosteroids.1

Mercaptopurine may be able to prevent Crohn's disease from coming back after surgery. It can at least lengthen the amount of time without disease after surgery. It's likely that azathioprine works as well.1

Both azathioprine and mercaptopurine can treat and heal fistulas.1

Methotrexate works to stop symptoms of active Crohn's disease and to put the disease in remission. It can keep Crohn's disease in remission when taken long term. It is also used to help people who have Crohn's disease stop taking corticosteroids.1

Ulcerative colitis

Azathioprine and mercaptopurine work to stop active symptoms of ulcerative colitis. They can also be used to help people who have ulcerative colitis stop taking corticosteroids.1

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you have:

Azathioprine and mercaptopurine

Call your doctor if you have:

Common side effects include:


Call your doctor if you have:

Common side effects include:

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

These medicines can stop your immune system from fighting infection. When you are taking this medicine (and even when you have finished taking it), try not to be around people who are sick. And make sure you talk to your doctor before you get any vaccinations.

These medicines may increase your risk of getting cancer, including lymphoma.

Do not drink alcohol when you are taking these medicines. Combining alcohol with these medicines can increase your risk for liver damage.

Other immunomodulators that may be used for Crohn's disease include mycophenolate mofetil (CellCept), tacrolimus (Prograf), and thalidomide (Thalomid).

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

Azathioprine and mercaptopurine

Women who use this medicine during pregnancy have a slightly higher chance of having a baby with birth defects. If you are pregnant or planning to get pregnant, you and your doctor must weigh the risks of using this medicine against the risks of not treating your condition.


Do not use this medicine if you are pregnant, breast-feeding, or planning to get pregnant. If you need to use this medicine, talk to your doctor about how you can prevent pregnancy.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.


  1. American Gastroenterological Association (2006). American Gastroenterological Association Institute medical position statement on corticosteroids, immunomodulators, and infliximab in inflammatory bowel disease. Gastroenterology, 130(3): 935-939. Also available online:

ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerArvydas D. Vanagunas, MD - Gastroenterology

Current as ofNovember 14, 2014

WebMD Medical Reference from Healthwise

Last Updated: November 14, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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