Azathioprine for inflammatory bowel disease

This leaflet is about the use of azathioprine for Crohn’s disease and ulcerative colitis, which are known as inflammatory bowel diseases.

Information Standard quality markThis leaflet has been written specifically about the use of this medicine in children. The information may differ from that provided by the manufacturer. Please read this leaflet carefully. Keep it somewhere safe so that you can read it again.

Name of drug

Azathioprine
Brand names: Imuran®

Why is it important to take this medicine?

In inflammatory bowel diseases, parts of the colon (large intestine), small intestine, rectum (back passage) and anus become inflamed (red and swollen) and ulcers (sores) may form. This causes symptoms such as diarrhoea, pain, stomach cramps and bleeding from the rectum. In some people, inflammatory bowel diseases are caused by the immune system attacking its own body.

Azathioprine belongs to a group of medicines called immunosuppressants. It works by helping to stop your child’s immune system from attacking their bowel. This reduces the inflammation in the bowels and so reduces the painful symptoms. 

What is azathioprine available as?

  • Tablets: 25 mg (orange), 50 mg (yellow); Imuran tablets contain lactose
  • Liquid medicine can be ordered specially from your pharmacist; this may contain a small amount of lactose.

When should I give azathioprine?

  • Azathioprine is usually given once a day. This can be in the morning OR the evening.
  • Your doctor may tell you to give it twice a day. This should be once in the morning and once in the evening. Ideally, 10–12 hours apart, for example between
  • 7 and 8 am, and between 7 and 8 pm.

Give the medicine at about the same time(s) each day so that this becomes part of your child’s daily routine, which will help you to remember.

How much should I give?

Your doctor will work out the amount of azathioprine (the dose) that is right for your child. The dose will be shown on the medicine label. 

It is important that you follow your doctor’s instructions about how much to give.

How should I give it?

Give azathioprine after your child has eaten and with a glass of water.
Tablets should be swallowed with a glass of water, milk or juice. Your child should not chew the tablet. You can crush the tablet and mix it with a small amount of soft food such as yogurt, honey or jam. Make sure your child swallows it straight away, without chewing. Wash your hands and all equipment used thoroughly afterwards to make sure that no-one else takes any of the medicine.
Liquid medicine: Measure out the right amount using an oral syringe or medicine spoon. You can get these from your pharmacist. Do not use a kitchen teaspoon as it will not give the right amount.

When should the medicine start working?

Azathioprine takes several weeks or even months to start working properly. It may take up to 3 months before you start to see any improvement in your child. It is important that you continue to give azathioprine during this time. 

What if my child is sick (vomits)?

  • If your child is sick less than 30 minutes after having a dose of azathioprine, give them the same dose again. 
  • If your child is sick more than 30 minutes after having a dose of azathioprine you do not need to give them another dose. Wait until the next normal dose.

What if I forget to give it?

If you usually give it once a day in the morning: Give the missed dose when you remember during the day, as long as this is at least 12 hours before the next dose is due.

If you usually give it once a day in the evening: If you remember before bedtime, give the missed dose. You do not need to wake a sleeping child to give them the missed dose. You can give the missed dose in the morning, as long as this is at least 12 hours before the evening dose is due.

If you normally give it twice a day: If you remember up to 4 hours after you should have given a dose, give your child the missed dose. For example, if you usually give a dose at about 7 am, you can give the missed dose at any time up to 11 am. If you remember after that time, do not give the missed dose. Wait until the next normal dose.

Never give a double dose of azathioprine.

What if I give too much?

It is unlikely that azathioprine will cause any harm if you give your child an extra dose by mistake. If you are worried that you may have given your child too much azathioprine, contact your doctor or NHS Direct (0845 46 47 in England and Wales; 08454 24 24 24 in Scotland). Have the medicine packaging with you if you telephone for advice.

Are there any possible side-effects? 

We use medicines to make our children better, but sometimes they have other effects that we don’t want (side-effects). 

Side-effects you must do something about

If your child gets flu-like symptoms, sore throat, or unusual bleeding or bruising, contact your doctor, as there may be a problem with your child’s blood.

If your child starts being sick every few hours, has stomach pains, is very sleepy or has jaundice (the skin or eyes look yellow), take them to your doctor or hospital straight away, as there may be a problem with your child’s liver.

Other side-effects you need to know about

Your child may get these side-effects when they first start taking azathioprine. They will usually settle down within a week or so as their body gets used to the medicine. Continue to give azathioprine to your child as your doctor has told you to. Contact your doctor if the side-effects go on for longer than a week.

  • Your child may feel sick (nausea) and have some diarrhoea. It may help to give azathioprine with some food or shortly afterwards.
  • Your child may feel less hungry (lose their appetite). Encourage them to eat small meals often.

Can other medicines be given at the same time?

  • You can give your child medicines that contain paracetamol or ibuprofen, unless your doctor has told you not to.
  • Azathioprine should not be taken with some medicines that you get on prescription. Tell your doctor and pharmacist about any other medicines your child is taking before giving azathioprine

Always check with your doctor or pharmacist before giving any other medicines to your child. This includes herbal or complementary medicines.

Is there anything else I need to know about this medicine?

  • Azathioprine affects your child’s immune system so they may get more infections such as chest infections, coughs and colds. Try to keep your child away from people with serious infections if you can, although they can still go to school or nursery as usual.

If your child comes into contact with anyone who has chickenpox or shingles, contact your doctor straight away, as they may need special preventative treatment. 

If you or your child comes into contact with anyone who has measles, contact your doctor, as infections can be more severe.

  • Your child will need regular blood tests to check whether azathioprine is affecting their blood, kidneys or liver. These tests will need to be done every week for the first month that your child is taking azathioprine and then at least every 3 months. It is important that you take your child for these blood tests.
  • Protect your child’s skin from strong sunlight by dressing them in long-sleeved tops, trousers and a hat, and using high-factor sunscreen (at least SPF 30). This is because there is a theoretical risk (but not proven) of your child getting some types of cancer, including skin cancer, if they take azathioprine for a long time (several years).
  • If your child is due to have an immunisation (vaccination), tell the nurse or doctor that your child is taking azathioprine. 
  • Azathioprine may harm an unborn baby. If your daughter is sexually active, it is vital that she uses adequate contraception to prevent unplanned pregnancy. The oral contraceptive pill can be used safely in women or girls taking azathioprine. If your daughter is worried that she may be pregnant, it is important that she sees your family doctor as early as possible. Your daughter should keep taking her medicine until she sees her doctor.

General advice about medicines

  • Try to give medicines at about the same times each day, to help you remember.
  • Only give this medicine to your child. Never give it to anyone else, even if their condition appears to be the same, as this could do harm. 

If you think someone else may have taken the medicine by accident, contact your doctor straight away.

  • Make sure that you always have enough medicine. Order a new prescription at least 2 weeks before you will run out.
  • Make sure that the medicine you have at home has not reached the ‘best before’ or ‘use by’ date on the packaging. Give old medicines to your pharmacist to dispose of.

Where I should keep this medicine? 

  • Keep the medicine in a cupboard, away from heat and direct sunlight. It does not need to be kept in the fridge.
  • Make sure that children cannot see or reach the medicine.
  • Keep the medicine in the container it came in.

Who to contact for more information 

Your child’s doctor, pharmacist or nurse will be able to give you more information about azathioprine and about other medicines used to treat inflammatory bowel diseases.


You can also get useful information from:


Publication Date

9/9/2011

Copyright Disclaimer

Version 1.2, July 2011 (December 2011). © NPPG, RCPCH and WellChild 2011, all rights reserved. Reviewed by: July 2013. 

The primary source for the information in this leaflet is the British National Formulary for Children. For details on any other sources used for this leaflet, please contact us through our website, www.medicinesforchildren.org.uk.

We take great care to make sure that the information in this leaflet is correct and up-to-date. However, medicines can be used in different ways for different patients. It is important that you ask the advice of your doctor or pharmacist if you are not sure about something. This leaflet is about the use of these medicines in the UK, and may not apply to other countries. The Royal College of Paediatrics and Child Health (RCPCH), the Neonatal and Paediatric Pharmacists Group (NPPG), WellChild and the contributors and editors cannot be held responsible for the accuracy of information, omissions of information, or any actions that may be taken as a consequence of reading this leaflet.