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Drug Class: Commonly Known As: Category:
Antimetabolite Adult

Azathioprine - Additional Information

How LONG does it take for the medicine to be EFFECTIVE?

  • It usually takes between 1 and 3 months to notice any improvement in symptoms after starting azathioprine.

When do I seek medical attention IMMEDIATELY?

  • Come back to the hospital if you have:
    • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
    • A temperature that exceeds 38°C or other symptoms of infection such as chills, cough or painful urination.
    • Feeling very tired or weak.
    • If you see tablet bits in the stool.
    • Excessive diarrhea and/or vomiting despite taking medicine.
    • Very bad skin irritation.
    • Jaundice (eyes or skin turn yellow).
    • Breathlessness


  • Your doctor may prescribe pain-relieving treatments since Azathioprine is not a pain killer.
  • Always check with the doctor or pharmacist first before self-treatment with any over-the-counter medicines.
  • DO NOT take any supplements, alternative or herbal medicines without informing your doctor or pharmacist.

What special DIETARY instructions should I follow?

  • Maintain adequate hydration (2-3 liters of fluid a day, unless otherwise advised by your doctor) and nutrition (small, frequent meals are preferred).
  • Alcohol should be avoided if possible or kept to a minimum as suggested by your rheumatologist because alcohol may increase the risk of liver toxicity associated with azathioprine.


  • Azathioprine may affect sperm formation and quantity.
  • Azathioprine may also potentially cause harm to the fetus. Do inform your doctor if you are pregnant or preparing for pregnancy or breastfeeding.

In SUMMARY… what you need to know about azathioprine?

  • Take azathioprine approximately at the same time every day, unless instructed otherwise by your doctor.
  • Always come for your BLOOD TESTS on the scheduled date.
  • Beware of the SIDE EFFECTS and when to get immediate medical attention.
  • Never take medicines, supplements or herbal treatments OVER-THE-COUNTER without checking with your doctor or pharmacist first.
  • If you (both genders) intent to start a family, please inform your doctor as azathioprine may affect your fetus and sperm count.
  • If you have further questions about Azathioprine, please call ______________________ (office number) to discuss with your doctor / pharmacist / specialty nurse (please circle as appropriate).
  • Updated on 2/28/2016 12:00:00 AM
  • Article contributed by Pharmacy Department, Rheumatology & Immunology KK Women's and Children's Hospital, Singapore General Hospital
The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth


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