Azathioprine is a medicine that modifies your immune system. It is usually used to treat diseases such as Systemic Lupus Erythematosus (SLE), inflammatory myositis and vasculitis. Occasionally, it is also used in the management of rheumatoid arthritis.

What is this medication used for

  • Azathioprine is a medicine that modifies your immune system. It is usually used to treat diseases such as Systemic Lupus Erythematosus (SLE), inflammatory myositis and vasculitis. Occasionally, it is also used in the management of rheumatoid arthritis.

Dosage and How to Use

  • Azathioprine is usually taken orally, with or after food to reduce stomach upset. It can cause nausea and vomiting at the start of therapy, but if the dose is increased slowly, your body will usually get used to it.

  • Dosage of Azathioprine will depend on your body weight, disease activity and response to the medication.

  • This medicine does not work immediately. It may take between 6 to 12 weeks before you notice any benefit. Thus it is important that you take your medication regularly, otherwise you may not benefit at all.

  • If you miss a dose, take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular dose. Do not double the dosage to make up for the missed dose.

Side Effects, Precautions, Contraindication

Can azathioprine be taken with other medications?

  • Azathioprine is often given together with corticosteroids to treat autoimmune diseases when steroid therapy alone has provided inadequate control.

  • Live vaccines should be avoided. Talk to your doctor before receiving immunizations or vaccinations. Also, direct contact with persons who have taken oral polio vaccine or those with infections should be avoided.

  • Allopurinol (a medication for gout) should NOT be taken with Azathioprine as it may interfere with removal of Azathioprine from the body, increasing its immunosuppressive effects as well as side effects.

  • Do not drink alcohol while on Azathioprine as alcohol can increase the risk of liver problems.

  • Please inform your doctor, pharmacist or rheumatology nurse clinician if you are taking other medications including over-the-counter medicines, supplements and traditional/herbal remedies as they may interact with Azathioprine.

What are the important side effects of azathioprine?

  • Many of the side effects occur at higher dosage and are usually reversible when the dose is reduced. On rare instances, individuals may experience rapid drop in white blood cell and platelet counts or abnormalities in liver function shortly after starting the medicine, which recover after the medicine is stopped.

  • Due to the way that Azathioprine works, some side effects may present only years after the medication is used. Always discuss with your doctor if you experience any side effects.

Side Effects


Nausea, vomiting, diarrhoea or loss of appetite

Take medication after food to minimise the side effects. Sucking hard, sugar-free candy may reduce nausea and vomiting. Inform your doctor if symptoms are severe or if you experience loss of appetite.

Loss of hair

This is harmless and may not be obvious. It often resolves spontaneously.

Liver disorder

(Warning signs: Yellowing of eye whites or skin, dark or tea-coloured urine or constant abdominal pain)

Consult your doctor immediately. Avoid alcohol. Inform your doctor if you previously had jaundice or hepatitis.

Blood disorder (rare side effect)

(Warning signs: May be asymptomatic; unusual bleeding or bruising, lip or mouth ulcers with “flu-like” symptoms may occur)

Consult your doctor immediately if these symptoms occur. It is important to monitor the effects of your new treatment, particularly during the first three months of treatment. For your safety, you need to do regular blood tests for monitoring.

If you develop rashes, facial swelling or shortness of breath after taking the medication, you could be allergic to the medication. Please seek medical attention immediately.

Are there any special precautions that I need to take?

  • Avoid overcrowded places and consumption of raw or undercooked food.

  • Azathioprine is generally considered safe in pregnancy. Please discuss with your doctor if you plan to start a family or to breastfeed.

  • If you develop a fever, sore throat or feel generally unwell, see a doctor immediately as you may be more susceptible to infections while on Azathioprine. The doctor whom you consult should be told that you are on Azathioprine.

Handling and Storage

  • Store your medication in a cool, dry place away from heat, moisture and direct sunlight.

If you have any problem with your treatment, please contact your doctor, pharmacist or rheumatology nurse clinician.

Please keep all medications out of reach of children.

© Tan Tock Seng Hospital, Singapore 2017. All rights reserved. All information correct as of August 2017. No part of this document may be reproduced, copied, reverse compiled, adapted, distributed, commercially exploited, displayed or stored in a database, retrieval system or transmitted in any form without prior permission of Tan Tock Seng Hospital. All information and material found in this document are for purposes of information only and are not meant to substitute any advice provided by your own physician or other medical professionals.



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