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Azathioprine, first used for clinical immunosuppression in 1961, is an immunosuppressant drug that prevents the body from rejecting a transplanted organ. It is typically used with other drugs after a kidney transplant, and can also be used to treat severe rheumatoid arthritis and ulcerative colitis.


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  • Tell your doctor if you have ever had liver or kidney disease.
  • The effects of azathioprine may cause increased infections and delayed healing. If you are having surgery, including dental surgery, tell your doctor or dentist that you are taking azathioprine.
  • If you can, avoid contact with people with colds or other infections.
  • Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums.
  • Do not touch your eyes or the inside of your nose unless you have just washed your hands.
  • Be careful not to cut yourself when you are using sharp objects such as a safety razor, fingernail or toenail cutters.
  • Avoid contact sports or other situations where bruising or injury could occur.

How Azathioprine Works

Azathioprine is an antimetabolite that reduces inflammation and interferes with the growth of rapidly dividing cells, including sensitized T- and B-cell clones. It has a generalized effect on bone marrow, inhibiting production of blood-forming cells. While suppressing these cells to help prevent rejection, azathioprine may also inhibit the production of other white blood cells used to combat infection. That’s why you and your transplant team must always be on the lookout for infection.

Taking Azathioprine

  • Take azathioprine exactly as directed by your doctor. If you do not understand these directions, ask your doctor, nurse or pharmacist to explain them to you.
  • Keep out of the reach of children.
  • Do not store azathioprine in the bathroom, near the kitchen sink or in other damp places. Heat or moisture may cause the medicine to break down.
  • Throw away any medication that is outdated or no longer needed, and talk to your pharmacist about the proper disposal of your medication.


If you miss a dose. When you start to take azathioprine, ask your doctor what you should do if you forget a dose and write down these directions so that you can refer to them later. If you miss more than one dose, it is important that you call your doctor.

Over Dosage. In case of overdose, call your local poison control center. If the victim has collapsed or is not breathing, call local emergency services at 911.

Common Side Effects

Although side effects from azathioprine are not common, they can occur. Tell your doctor if any of these symptoms are severe or do not go away:

  • cold hands and feet
  • diarrhea
  • joint pain
  • loss of appetite
  • upset stomach
  • vomiting

Dangerous Side Effects

If you experience any of the following symptoms, call your doctor immediately:

  • blood in urine
  • bloody or dark, tarry stools
  • chills
  • fast heartbeat
  • fever
  • mouth sores
  • shortness of breath
  • skin rash
  • sore throat
  • unusual bleeding or bruising
  • vision changes
  • yellowing of the skin or eyes

Azathioprine and Pregnancy

Use of azathioprine is not recommended during pregnancy. It may cause birth defects if either the male or the female is using it at the time of conception. Therefore, the use of birth control methods is recommended.

Because azathioprine also passes into breast milk and may harm a nursing infant, breast-feeding is generally not recommended while you are using azathioprine.

Drug Interactions

Before taking azathioprine, tell your doctor if you are taking, have taken, or need to take any of the following medicines:

Allopurinol (e.g., Zyloprim); Benzepril (e.g. Lotensin); Captopril (e.g. Capoten); Chlorambucil (e.g. Leukeran); Corticosteroids; Cyclophosphamide (e.g., Cytoxan); Cyclosporine (e.g. Neoral, Sandimmune); Enalapril (e.g. Vasotec); Fosinopril (e.g. Monopril); Lisinopril (e.g. Zestril); Mercaptopurine (e.g. Purinethol); Methotrexate; Muromonab-CD3 (monoclonal antibody) (e.g., Orthoclone OKT3); Quinipril (e.g. Accupril); Ramipril (e.g. Altace); Warfarin (e.g. Coumadin); Vaccinations; Vitamins

Brand Names

Imuran, manufactured by Prometheus Laboratories, Inc.

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