Updated February 2023

What is azathioprine?

Download button - information sheetAzathioprine is a medication used to treat certain childhood rheumatic conditions (diseases which may affect kidneys, joints, muscles, skin, gut or eyes). This can include lupus (also known as SLE), inflammatory bowel disease, uveitis and scleroderma. People who have had organ transplants also use it.

Azathioprine is a medication that works by suppressing your immune system. It reduces the damage done by inflammation, rather than just reducing pain.

Important things to remember

  • You must see your rheumatologist regularly to make sure the treatment is working and check for possible side effects.
  • You should have regular blood tests as suggested by your rheumatologist.
  • If you are worried about any side effects, you should contact your rheumatologist as soon as possible.
  • If you stop azathioprine for any reason, you must contact your rheumatologist.

How will it help?

Azathioprine is a medication that works slowly. You can expect your child to gradually start feeling better, but it might take one to three months.

How is azathioprine given?

Azathioprine is available as oral tablets.

What is the dose and how often is it given?

This depends on the weight of your child. It is usually started at a low dose, which is then increased. The final dose is adjusted according to response and side effects.
It is taken either once or twice a day.

How long will it be used for?

People stay on azathioprine for long periods (several years) to help keep their disease under control.

Are there any side effects?

Azathioprine is usually very effective in improving your child’s condition but, like all medications, side effects can occur. Some are common, and some are rare. Most people don’t have any problems when they take azathioprine. Regular blood tests are important to monitor side effects.

Most common side effects


Nausea (feeling sick) vomiting, loss of appetite & diarrhoea

  • Dose alteration
  • Take dose with food
  • Anti-emetics (anti-sickness medication)

Skin rash / sun sensitivity

  • Use high factor sunscreen and hats

Mouth ulcers Sore gums

Sore throat

  • Dose reduction; tell your doctor


Rare side effects


Disturbance in the blood counts (change in blood tests results)

Upset liver function

Pancreatitis (felt as very bad stomach pain)

Allergic reactions and serious skin reactions

  • Usually returns to normal if azathioprine dose reduced or stopped

Things you need to know when your child is taking this medication

What to do if your child is sick
Normal coughs and colds are okay. Don’t give azathioprine if your child:

  • Has a high fever
  • Has had vomiting/ diarrhoea
  • Has been in contact with chickenpox, shingles or herpes zoster
  • Is sick and you’re not sure why

If you’re not sure, talk to your doctor, and get your child checked if necessary before giving the azathioprine.

Azathioprine can interact with other medications. Talk to your doctor before your child takes any prescription medications, natural medications and any medications that you can buy over the counter.

Most immunisations are safe to have (flu vaccine, cervical cancer vaccine, killed polio vaccine (IPV) etc) when taking this medication.
Live virus vaccines (such as mumps, measles, rubella (MMR), polio (OPV)), varicella (chicken pox) and some travel vaccines should not be used.

Patients on azathioprine are at increased risk of infection, because of immune suppression.
Azathioprine can make chickenpox infections more serious. A blood test can be done to see if your child is already immune to the virus. If your child is in contact with chickenpox or shingles, call your doctor.

Azathioprine and alcohol are both broken down by the liver. Drinking alcohol while you are on this medication can put extra strain on the liver. It is not known how much is safe, so it is suggested that anyone on azathioprine should avoid drinking alcohol.

Sexual health and pregnancy
Having been on azathioprine in the past does not change your chances of having babies when you are older. Azathioprine appears to be relatively safe in pregnancy and breastfeeding.

Myths and misconceptions
You may hear a lot of different information about azathioprine from friends, pharmacists or people that you know. If you are worried about anything, please talk to your child’s doctor or nurse.

If your child is taking azathioprine they should see their paediatric rheumatologist regularly to make sure the treatment is working and to minimise any possible side effects.