Imuran is a drug whose active ingredient is azathioprine. It reduces the activity of the immune system. It can be used in some suitable patients, particularly for the treatment of inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis.

Imuran is not a steroid (cortisone) or an antibiotic. It is not addictive.

How does Imuran work?

In Crohn’s disease and ulcerative colitis, the immune system causes a long-lasting inflammatory reaction in the bowel.

Azathioprine reduces the multiplication and activity of immune cells and so helps keep this inflammation under control.

The drug does not work straight away. It usually takes from a few weeks to a few months before there is a clear benefit.

For this reason, Imuran is not a drug used to bring sudden, severe flare-ups of the disease quickly under control.

What is it used for?

Crohn’s disease

Crohn’s disease is a chronic disease that can cause inflammation in different parts of the digestive system.

Azathioprine can be used in selected patients to help keep the disease under control.

Today, using it on its own is not suitable for every patient. In some patients it can be used together with biological drugs.

Ulcerative colitis

Ulcerative colitis is a chronic disease that causes inflammation of the inner lining of the large bowel.

Azathioprine can be used to keep the disease under control, particularly in some patients who improve with steroid (cortisone) treatment but flare up again when the steroid is reduced.

However, it is not suitable for the rapid treatment of acute severe ulcerative colitis.

Other diseases

Azathioprine can also be used to suppress the immune system after organ transplantation and in some immune system diseases.

The decision to use it in these diseases is made by the relevant specialist.

How is Imuran taken?

Imuran is taken by mouth as a tablet.

The dose is decided according to the patient’s weight, blood tests, kidney and liver function, other medicines and response to treatment.

Before treatment starts, some patients may need tests of enzyme and genetic characteristics called TPMT and NUDT15. These tests help identify the risk of the drug causing serious side effects.

Take the drug at the dose your doctor recommends.
Do not increase or reduce the dose on your own.
Regular blood tests should be done during treatment.
Even if your complaints improve, do not stop the drug without your doctor’s advice.
Do not take a double dose to make up for a missed one.

What are the side effects of Imuran?

Azathioprine is an effective drug, but it can cause some important side effects.

More common side effects

Nausea
Loss of appetite
Abdominal discomfort
Tiredness
Raised liver tests

More serious side effects

Suppression of the bone marrow: The number of white blood cells, red blood cells or platelets can fall. This can increase the risk of infection, anaemia or bleeding.

Pancreatitis: Some patients can develop acute inflammation of the pancreas caused by the drug. It can appear particularly in the first weeks of treatment.

Liver damage: Liver tests can worsen and, rarely, more serious liver problems can occur.

Infections: Suppression of the immune system can increase the risk of some infections.

Cancer risk: With long-term use, the risk of lymphoma and some skin cancers in particular can rise. This risk is not the same for every patient and should be weighed against the benefits of treatment.

Which symptoms mean I should see a doctor?

The following symptoms are important in patients taking Imuran:

High fever or clear signs of infection
Severe and constant abdominal pain
Repeated vomiting
Unexplained bruising or bleeding
Marked tiredness
Jaundice
A widespread skin rash

Severe abdominal pain in particular may need assessment for pancreatitis.

Which check-ups are needed while taking Imuran?

Regular monitoring is very important in azathioprine treatment.

Before and during treatment the following tests are usually assessed:

Full blood count
Liver function tests
Kidney function tests
TPMT and NUDT15 testing when needed

The checks are more frequent early in treatment. Once the patient is stable, the doctor arranges the intervals between checks.

Normal TPMT or NUDT15 results do not remove the need for regular blood tests.

Does it interact with other medicines?

Yes. Azathioprine can have important interactions with some medicines.

In particular, using it together with uric acid-lowering drugs such as allopurinol and febuxostat can lead to severe suppression of the bone marrow.

Using it together with allopurinol may be possible in some patients, but only with special dose adjustment and close monitoring. Using it together with febuxostat is generally not recommended.

Mesalazine and some other medicines can also change the effect of azathioprine or its risk of side effects.

For this reason, all the medicines you take should be reported to your doctor.

Can Imuran be used in pregnancy?

Azathioprine is not a drug that is strictly forbidden in pregnancy in every situation.

In some patients with Crohn’s disease or ulcerative colitis, continuing treatment during pregnancy may be appropriate to keep the disease under control.

The decision should be made by assessing the severity of the disease, the dose used and the condition of the mother and the baby.

Patients who are planning a pregnancy or find out they are pregnant should not stop the drug on their own, but should talk to their doctor.

Frequently asked questions

Is Imuran a steroid (cortisone)?

No. Imuran is not cortisone. It belongs to a different group of drugs that reduce the activity of the immune system.

Is Imuran addictive?

No. It is not addictive. However, because the disease continues, the treatment may need to be kept up for a long time.

How long does Imuran take to work?

The effect of the drug develops slowly. A clear clinical benefit usually appears within a few weeks to a few months.

Is Imuran given to every patient with Crohn’s disease or ulcerative colitis?

No. There are different treatment options today. Azathioprine can be used in selected patients, on its own or together with other drugs.

Can I be vaccinated while taking Imuran?

Many inactivated vaccines can be given and are important for protection against infections. However, live vaccines can be harmful in patients whose immune system is suppressed. The vaccination plan should be assessed by the doctor.

Can I go out in the sun while taking Imuran?

Yes, but protecting yourself from the sun is important. Because the risk of some skin cancers can rise with long-term azathioprine use, using sunscreen and, where needed, skin check-ups by a dermatologist are recommended.

Important: This page has been prepared to inform patients. Imuran treatment needs regular blood tests and follow-up by a doctor. The dose should not be changed and the treatment should not be stopped without a doctor’s advice.

Imuran (azathioprine)