Medication used in IBD


This information has been provided with kind permission from Crohn’s and Colitis UK - a nationwide charity committed to providing information and support, funding crucial research and working to improve healthcare services for anyone affected by Inflammatory Bowel Disease.

The main immunosuppressants used in IBD include:

  • azathioprine (Imuran) and mercaptopurine or 6-MP (Puri-nethol)
  • methotrexate
  • mycophenolate mofetil
  • ciclosporin
  • tacrolimus.

Azathioprine and mercaptopurine

These two drugs have been used to treat IBD for many years and have been shown to be very effective at reducing symptoms and maintaining remission in both Crohn’s and UC. However, they act slowly and it may be several months before you notice any benefit.

Because azathioprine and mercaptopurine are immunosuppressants and affect the way the immune system works, people taking them tend to be more susceptible to infections, such as cold and flu. So you will be advised to have an annual flu vaccination. You may also need an extra vaccination against infectious diseases such as measles, chickenpox or shingles, and some forms of pneumonia as these illnesses can be more severe in people on immunosuppressants.

These drugs also increase the skin’s sensitivity to sunlight and the risk of developing some types of skin cancer, so it is best to use sunblock and to avoid sunlamps or sunbeds.

Side effects can include:

  • especially at first, nausea, or a flu-like illness with fever, and general aches and pains
  • a sudden worsening of diarrhoea
  • less commonly, inflammation of the liver, and/or the pancreas (pancreatitis) anaemia
  • suppression of the bone marrow function which can lead to anaemia
  • a slightly increased risk of developing lymphoma (a type of cancer affecting the lymph glands). However, research suggests that for most people taking these drugs the risk is very small and likely to be outweighed by the potential benefits.

Regular monitoring is important for people taking immunosuppressants. At first you will need frequent blood tests, usually weekly or fortnightly. As you become used to the treatment you will probably move to having a blood test every two to three months, for as long as you are on azathioprine or mercaptopurine.


Methotrexate is used to help bring about and maintain remission in people with Crohn’s who are steroid dependent (cannot stop steroid treatment without having a relapse) and who do not respond well to azathioprine or 6-MP. Occasionally, it is used to treat UC, but there is there less evidence of its effectiveness for this condition.

Methotrexate is taken only once a week, as tablets or by injection. Like azathioprine, is slow acting and it may take up to three months before symptoms improve.

As an immunosuppressant, methotrexate can cause a greater susceptibility to infections. It also increases the skin’s sensitivity to sunlight and the risk of developing some types of skin cancer.

Side effects can include:

  • nausea and diarrhoea, especially at the beginning of treatment
  • more rarely, suppression of the bone marrow production
  • liver and kidney problems.

If you are a woman it is important not to become pregnant while you or your partner are taking methotrexate, as it can have serious effects on the unborn baby. You should stop taking methotrexate at least six months before trying to conceive.

You will need to have blood tests and tests to check liver and kidney function before starting methotrexate, and then regular blood tests while you continue on methotrexate treatment.

Mycophenolate mofetil

Mycophenolate mofetil has been used for many years for cancer treatment and after organ transplants. More recently it has been used for people with IBD who do not respond well to other immunosuppressants or biologics. Some studies have found it to be effective in bringing about steroid-free remission, but more research is needed in this area.

The possible side effects are similar to those with methotrexate and you will need regular blood checks.


Ciclosporin is used widely for preventing the body’s rejection of organ transplants. It is also useful in various conditions caused by a reaction of the body against its own tissues. In IBD, ciclosporin is generally used to treat severe UC flare-ups and may help to avoid or delay surgery to remove the large bowel. It can be a useful treatment while a slower acting drug, such as azathioprine, is building up its effectiveness.

Ciclosporin is usually given intravenously and in hospital to begin with, but may then be given as an oral preparation (in capsule or as a drink), over a period of three to six months.

Side effects can include:

  • nausea, headache, tingling of the hands or feet
  • growth of hair on the face
  • swollen gums
  • reduced kidney function (usually temporary) and a rise in blood pressure.

You will be given regular blood and kidney function tests while you are being treated with ciclosporin – probably weekly at first, and then about once a month.


Tacrolimus is similar in action to ciclosporin but may be used for severe Crohn’s as well as for UC. It works quickly and can be taken with azathioprine until this slower acting drug becomes effective. Tacrolimus can be taken orally from the start so does not necessarily require a hospital stay. It is also available as an ointment and may be helpful for Crohn’s in the anal area and UC in the rectum.

Tacrolimus taken orally tends to have side effects similar to those of ciclosporin.

© Crohn’s and Colitis UK 2015

About the author

This information has been provided with kind permission from Crohn’s and Colitis UK – a nationwide charity committed to providing information and support, funding crucial research and working to improve healthcare service for anyone affected by  Inflammatory Bowel Disease.

Information and Support Line: 0300 222 5700

Visit for more information and a full list of their information sheets, booklets and guides.

To support their vital work, donate to Crohn’s and Colitis UK here

The Crohn's and Colitis Charity


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