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Generic Name: azathioprine (AY-za-THYE-oh-preen)
Brand Name: Examples include Azasan and Imuran

Long-term use of Imuran increases the risk of developing certain types of cancers (eg, leukemia, lymphoma, skin cancer). A rare type of cancer called hepatosplenic T-cell lymphoma (HSTCL) has been reported in patients treated with Imuran. These cases have been fatal. Most of these cases occurred in teenagers and young adults who had Crohn disease or ulcerative colitis. Some patients who developed this cancer were using Imuran along with certain other medicines called TNF blockers (eg, infliximab). Tell your doctor if you have or have ever had any type of cancer.

Imuran may also cause serious blood disorders (eg, anemias, low white blood cell or platelet levels). Discuss any questions or concerns with your doctor.

Contact your doctor at once if you develop changes in the appearance or size of a mole; easy bruising or bleeding; unusual growths; unusual lumps or swelling (eg, in your neck, armpit, groin); persistent, unexplained itching; night sweats; signs of infection (eg, fever, chills, persistent sore throat); stomach pain or tenderness; unusual tiredness or weakness; or unexplained weight loss.


Imuran is used for:

Preventing kidney transplant rejection when used along with other medicines. It may also be used to reduce signs and symptoms of active rheumatoid arthritis. It may also be used for other conditions as determined by your doctor.

Imuran is an antimetabolite. It works by decreasing the effects of certain cells in the body's immune system.

Do NOT use Imuran if:

  • you are allergic to any ingredient in Imuran
  • you have rheumatoid arthritis and are pregnant
  • you have rheumatoid arthritis and have used alkylating agents (eg, cyclophosphamide, chlorambucil, melphalan) in the past
  • you are taking febuxostat or mercaptopurine

Contact your doctor or health care provider right away if any of these apply to you.

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Before using Imuran:

Some medical conditions may interact with Imuran. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

  • if you are pregnant, planning to become pregnant, or are breast-feeding
  • if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
  • if you have allergies to medicines, foods, or other substances
  • if you have kidney or liver problems
  • if you have certain bowel problems (eg, Crohn disease, ulcerative colitis)
  • if you have an infection; a history of frequent, recurrent, or prolonged infections; or you have recently had or are scheduled to receive a vaccination
  • if you have a history of cancer, bone marrow problems, anemia, low white blood cell or platelet levels, or unusual bruising or bleeding
  • if you have certain enzyme deficiencies (thiopurine methyltransferase [TPMT] or xanthine oxidase) or you have recently had a blood transfusion
  • if you are taking a disease-modifying antirheumatic drug (DMARD) (eg, methotrexate, adalimumab)

Some MEDICINES MAY INTERACT with Imuran. Tell your health care provider if you are taking any other medicines, especially any of the following:

  • Alkylating agents (eg, cyclophosphamide, chlorambucil, melphalan) or TNF blockers (eg, certolizumab, etanercept) because the risk of developing certain types of cancer may be increased
  • Mercaptopurine because the risk of severe toxic effects, including severe bone marrow suppression or death, may be increased
  • Allopurinol, aminosalicylates (eg, mesalazine, olsalazine, sulfasalazine), angiotensin-converting enzyme (ACE) inhibitors (eg, enalapril), doxorubicin, febuxostat, ribavirin, or trimethoprim/sulfamethoxazole because they may increase the risk of Imuran's side effects
  • Anticoagulants (eg, warfarin) because their effectiveness may be decreased by Imuran

This may not be a complete list of all interactions that may occur. Ask your health care provider if Imuran may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

How to use Imuran:

Use Imuran as directed by your doctor. Check the label on the medicine for exact dosing instructions.

  • Take Imuran by mouth with or without food. If stomach upset occurs, take with food to reduce stomach irritation.
  • Ask your doctor if you should follow any special guidelines for handling Imuran.
  • If you miss a dose of Imuran, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Ask your health care provider any questions you may have about how to use Imuran.

Important safety information:

  • Imuran may lower the ability of your body to fight infection. Avoid contact with people who have colds or infections. Tell your doctor if you notice signs of infection like fever, sore throat, rash, or chills.
  • Imuran may reduce the number of clot-forming cells (platelets) in your blood. Avoid activities that may cause bruising or injury. Tell your doctor if you have unusual bruising or bleeding. Tell your doctor if you have dark, tarry, or bloody stools.
  • Tell your doctor or dentist that you take Imuran before you receive any medical or dental care, emergency care, or surgery.
  • Talk with your doctor before you receive any vaccine while you are taking Imuran.
  • Contact your doctor at once if you develop severe nausea and vomiting. This may occur with or without diarrhea, rash, fever, muscle pain, dizziness, fainting, or unusual tiredness. If this reaction occurs, it usually happens within the first several weeks of therapy.
  • Imuran may increase your risk of developing a tumor or other cancer. Contact your doctor at once if you notice any unusual growths or lumps. To decrease your risk of developing skin cancer, avoid the sun, sunlamps, or tanning booths. Use a sunscreen with a high protection factor and wear protective clothing if you must be outside for more than a short time. Discuss any questions or concerns with your doctor.
  • An enzyme called TPMT helps to break Imuran down in the body. Infrequently, some patients may have decreased TPMT enzyme activity. This may increase the risk of developing serious side effects (eg, severe bone marrow problems). Patients with decreased TPMT enzyme activity may need a lower dose of Imuran. Discuss any questions or concerns with your doctor.
  • A certain severe condition called progressive multifocal leukoencephalopathy (PML) has been reported with use of Imuran. PML is often fatal. Discuss any questions or concerns with your doctor. Tell your doctor at once if you notice new or worsening symptoms such as confusion; memory problems; difficulty talking or walking; changes in mood or behavior; or changes in thinking, eyesight, balance, or strength.
  • If you are able to become pregnant, talk with your doctor or pharmacist about the use of effective birth control while taking Imuran.
  • Lab tests, including complete blood counts, liver function, and TPMT enzyme activity, may be performed while you use Imuran. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
  • Imuran should be used with extreme caution in CHILDREN; safety and efficacy in children have not been confirmed.
  • PREGNANCY and BREAST-FEEDING: Imuran has been shown to cause harm to the fetus. Do not become pregnant while you are using it. If you think you may be pregnant, contact your doctor. You will need to discuss the benefits and risks of using Imuran while you are pregnant. Imuran is found in breast milk. Do not breast-feed while taking Imuran.

Possible side effects of Imuran:

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Mild nausea or vomiting.

Seek medical attention right away if any of these SEVERE side effects occur:

Severe allergic reactions (rash; itching; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); chest pain or tightness; dizziness; fatty stools; fever, chills, or persistent sore throat; increased or painful urination; muscle or joint pain or aches; painful, red bumps or blisters on the arms, face, neck, or back; severe or persistent nausea, vomiting, or diarrhea; shortness of breath; stomach pain; symptoms of liver problems (eg, dark urine, loss of appetite, pale stools, right-sided stomach pain, yellowing of the eyes or skin); unusual bleeding or bruising; unusual growths or lumps; unusual weakness or tiredness; warm, red, swollen, or painful skin.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

If OVERDOSE is suspected:

Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately. Symptoms may include fever, chills, or sore throat; severe or persistent diarrhea, nausea, or vomiting.

Proper storage of Imuran:

Store Imuran at room temperature, between 59 and 77 degrees F (15 and 25 degrees C), in a tightly closed container. Store away from heat, moisture, and light. Do not store in the bathroom. If you no longer need Imuran, ask your doctor how to properly dispose of it. Keep Imuran out of the reach of children and away from pets.

General information:

  • If you have any questions about Imuran, please talk with your doctor, pharmacist, or other health care provider.
  • Imuran is to be used only by the patient for whom it is prescribed. Do not share it with other people.
  • If your symptoms do not improve or if they become worse, check with your doctor.
  • Check with your pharmacist about how to dispose of unused medicine.

This information should not be used to decide whether or not to take Imuran or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about Imuran. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to Imuran. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using Imuran.

Issue Date: July 2, 2014
Database Edition 14.3.1.001
Copyright © 2014 Wolters Kluwer Health, Inc.

Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using this medicine.

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