Immunomodulators (immunosuppressants) for Crohn's disease and ulcerative colitis

Immunomodulators are medications which change how your immune system works. Find out more about them in this article.

What are immunomodulators?

Immunomodulators (IMs), often referred to as immunosuppressants, are a type of medication which weaken or modulate the activity of the immune system. In inflammatory bowel disease (IBD) immunomodulators decrease the body’s inflammatory response, which is thought to play a role in IBD flares. They have been used since the 1960s to treat Crohn’s disease and ulcerative colitis.

Types of immunomodulators include:

  • Azathioprine (brand names include Azasan, Imuran)
  • Mercaptopurine, also know as 6-mercaptopurine or 6-MP (brand names include Purinethol)
  • Methotrexate (brand names include Trexall, rheumatrex, MTX, Rheumatrex, Mexate, Jylamvo, Maxtrex, Methofill, Metoject, Nordimet, Zlatal)
  • Cyclosporine A (brand names include Neoral, Gengraf, Sandimmune)
  • Tacrolimus (brand names include Prograf)

You can get more specific information about some forms of immunomodulators in these articles:


How do immunosuppressants work in IBD?

Each immunomodulator works in a slightly different way, but they all change how your immune system functions.

Some work by suppressing or weakening the immune system and others change the way it works.

In Crohn’s disease and ulcerative colitis it’s thought the immune system is mistakenly attacking the digestive system, causing inflammation. By suppressing the immune system or changing how it works this reduces the inflammation which causes damage and symptoms.

Azathioprine, methotrexate and 6-Mercaptopurine can take between 3-6 months to build up to their maximum therapeutic range (the amount needed for it to effectively change your immune system) so may initially be combined with another medication which works faster, such as corticosteroids, to get your symptoms under control.

Immunomodulators are a maintenance medication, this means they are used to maintain remission of your IBD. Remission is where you don’t have active disease. Steroids are an induction therapy, a medication that works to get you into remission.

Cyclosporine, tarolimus and methotrexate are faster working, usually taking a couple of weeks to reach their therapeutic range.

Why have I been given an immunomodulator for my IBD?

In general immunosuppressant medications are used in people with moderate to severe Crohn’s disease or ulcerative colitis who have not responded well to aminosalicylates or corticosteroids, or to help if someone is steroid-dependent or needs to take steroids frequently to stay well. 

They are also used in people with perianal disease that does not respond to other treatment or people with fistulas

You may also be prescribed an immunomodulator to help biologic medications be more effective and to help stop you becoming resistant to biologics. Some people are also given them after having surgery to prevent a recurrence of their IBD.

How are immunomodulators taken?

How you take immunomodulators will depend on what type you have be prescribed and where you Crohn’s disease or ulcerative colitis is located.


Azathioprine and 6-Mercaptopurine, which are both chemically quite similar, are taken orally on a daily basis. Cyclosporine A, methotrexate and tacrolimus can also be taken orally. 


Tacrolimus comes as a cream or ointment which can be used to treat Crohn’s disease affecting the mouth or in the perineal area (your bum). It is also prescribed as a treatment for pyoderma gangrenosum, a skin condition which can affect people with IBD.


Methotrexate is taken by an injection, often weekly, which you will be taught how to do yourself at home.

What side effects are there of immunomodulators?

Reported side effects of azathioprine and 6-MP include:

  • Headache
  • Nausea/vomiting
  • Diarrhoea
  • Malaise (general feeling of illness)
  • Pancreatitis
  • Bone marrow suppression

Reported side effects of cyclosporine and tacrolimus include:

  • Decreased kidney function
  • Hepatitis
  • Increased risk of infections
  • Diabetes
  • Increased cholesterol levels
  • Sleep problems
  • Headache
  • Mild tremor
  • High blood pressure
  • Swollen gums
  • Tingling of the fingers and feet
  • Increased facial hair
  • Increased risk of lymphoma

Reported side effects of methotrexate include:

  • Flu-like symptoms (nausea, vomiting, headache, fatigue and diarrhoea
  • Low which blood cell count
  • Scarring of the liver (which can be made worse by diabetes, being overweight and alcohol consumption)
  • Lung inflammation

If you are experiencing any side effects which you are finding difficult to manage or which are troubling you then speak to your doctor. You should not stop taking your medication without speaking to them first.

Can I take other medications with immunomodulators?

When you first start taking immunomodulators it’s likely you will be prescribed another medication (an induction treatment) to take at the same time for a short period of time to help get your symptoms under control quickly.

You may also be asked to take a combination therapy longer-term, such as a biological medicine. This can help to increase the effectiveness of your treatment, but may also increase your risk of side effects.

If you are taking any other medicines, including over-the-counter, herbal or complementary medicines, you should let your doctor know before starting immunomodulators. Some medicines can interact with immunomodulators, causing them to be less effective or causing side effects.

What else do I need to know about immunosuppressants?

Some other things you should be aware of before starting immunomodulators include:

  • As immunomodulators suppress the immune system you may be susceptible to catching infections more easily. They can also have an effect on bone marrow, liver and kidneys, therefore you may be required to have regular blood tests to check these
  • You may not be able to have certain vaccinations while taking immunomodulators, such as live vaccinations. You should let your doctor know if you are due to have any vaccinations so they can give you advice
Funding to help in the production of this article was received from PredictSURE IBD, however they had no input into its content.

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