Oncology Certified Nurse Practitioner and freelance healthcare writer with over a decade of medical oncology and hematology experience.

Lindsay Cook, PharmD is a board-certified consultant pharmacist.

Imuran can increase the risk of developing cancer. Cancers related to the use of Imuran include leukemias, lymphomas, and solid tumor malignancies. Imuran can also cause severe suppression of the bone marrow, leading to decreased white blood cells, red blood cells, and platelets.

Imuran (azathioprine ) is a medication that works by suppressing the immune system. It is approved for use in people with rheumatoid arthritis (RA). Imuran is also used to prevent rejection of a kidney transplant.

Imuran works by decreasing the immune system’s ability to cause inflammation. This can be important when given for a kidney transplant, so the immune system can’t attack the new kidney and prevent it from working. In RA, Imuran prevents the immune system from being able to cause inflammation to the joints and can improve symptoms of RA. 

Brand Name(s): Imuran, Azasan

Controlled Substance: N/A

Dosage Form(s): Tablet

Imuran is used for people who have received a kidney transplant. When a kidney is transplanted, the immune system may recognize the new kidney as foreign and work to cause inflammation to reject the new kidney. Imuran suppresses the immune system and prevents it from rejecting the kidney. 

Imuran is also used to reduce the symptoms of RA. In RA, the immune system attacks the joints in the body, causing pain and swelling. Imuran suppresses the immune system to prevent pain and swelling.

How frequently Imuran should be taken is individual to each person and why they have been prescribed the medication. 

There are no special dietary restrictions with Imuran. 

Store Imuran at room temperature in its original packaging. It should be kept dry and away from light. 

Healthcare providers may prescribe Imuran for off-label uses, meaning for conditions not specifically indicated by the Food and Drug Administration (FDA). The conditions in which Imuran is used off-label are autoimmune or inflammatory conditions, in which the immune system is attacking healthy tissue and causing the disorder.

The most common off-label uses for Imuran are:

It may take Imuran a few weeks to work, and the effects can last for weeks after the medication has been stopped.

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the FDA at fda.gov/medwatch or 1-800-FDA-1088.

The most common side effects that Imuran can cause include:

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

Imuran has been associated with the development of cancer. For those who take Imuran for a kidney transplant, skin cancer and lymphoma are the most common cancers from Imuran.  

For those who take Imuran for RA, leukemia, a blood cancer, and cancers in the solid organs have been reported. The risk of developing cancer when taken for RA is lower than when taking Imuran for a kidney transplant.

Imuran may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

If your side effects become severe while taking Imuran, your healthcare provider may hold or reduce your dose.

If you miss a dose of Imuran, skip the missed dose and take it at the next scheduled time. Do not double up on doses to make up for the missed one.

If too much Imuran is taken, notify the prescribing healthcare provider immediately. Depending upon the dose taken, blood work or other monitoring may need to be done. 

If you think you or someone else may have overdosed on Imuran, call a healthcare provider or the Poison Control Center (800-222-1222). You may need to be monitored for adverse effects.

If someone collapses or stops breathing after taking Imuran, call 911 immediately.

It is very important that your doctor check your progress at regular visits for any problems that may be caused by this medicine. Blood and urine tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using this medicine, tell your doctor right away.

Do not use this medicine if you are also taking mercaptopurine (Purinethol®). Using these medicines together could cause serious unwanted effects.

If you are using azathioprine for arthritis, make sure your doctor knows if you had received chlorambucil (Leukeran®), cyclophosphamide (Cytoxan®, Neosar®), or melphalan (Alkeran®) to treat your arthritis in the past. Using azathioprine after these medicines may increase your risk for unwanted effects. Talk to your doctor if you have questions about this.

This medicine may increase your risk of getting certain types of cancer, especially of the skin, lymph system (lymphoma), or blood (leukemia). Talk to your doctor if you have concerns about this risk.

Use sunscreen or sunblock lotions with a sun protection factor (SPF) of at least 15 on a regular basis when you are outdoors. Wear protective clothing and hats, and stay out of direct sunlight between the hours of 10 am and 3 pm Avoid sunlamps and tanning beds.

While you are being treated with azathioprine, and after you stop treatment with it, do not have any immunizations (vaccines) without your doctor's approval. Azathioprine may lower your body's resistance and the vaccine may not work as well or you might get the infection the vaccine is meant to prevent. In addition, you should not be around other persons living in your household who receive live virus vaccines because there is a chance they could pass the virus on to you. Some examples of live vaccines include measles, mumps, influenza (nasal flu vaccine), poliovirus (oral form), rotavirus, and rubella. Do not get close to them and do not stay in the same room with them for very long. If you have questions about this, talk to your doctor.

Azathioprine can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

This medicine may increase your risk of developing infections, including a serious brain infection called progressive multifocal leukoencephalopathy. Avoid being near people who are sick or have infections while you are using this medicine. Wash your hands often. Tell your doctor if you have any kind of infection before you start using this medicine. Also tell your doctor if you have ever had an infection that would not go away or an infection that kept coming back.

Check with your doctor right away if you have more than one of these symptoms while you are using this medicine: severe nausea or vomiting, diarrhea, fever, rash, a general feeling of discomfort or illness, muscle or joint pain, lightheadedness or dizziness, or unusual tiredness or weakness. These could be symptoms of a serious reaction to the medicine in your bowel.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Do not use Imuran if you:

Imuran should not be taken along with some other medications. If taking these medications together is unavoidable, you may need a dosage adjustment or more frequent monitoring.

Medications that may interact with Imuran include:

Other medications that work similarly to Imuran to suppress the immune system include:

Imuran is used for rheumatoid arthritis and to prevent the rejection of kidney transplants. Healthcare providers sometimes prescribe it for off-label uses in inflammatory and autoimmune disorders.

Imuran works by suppressing the immune system and preventing it from causing inflammation. This treats the affected joints in rheumatoid arthritis and can prevent inflammation from rejecting the kidney transplant.

The most common side effects of Imuran are nausea, vomiting, and decreased blood counts. Severe side effects can include infections and liver dysfunction. Talk to your healthcare provider about what to expect before starting Imuran.

Because of the way Imuran suppresses the function of the immune system, it is important to be aware of any symptoms that need to be reported to your healthcare team. Notify your healthcare team if you have any new symptoms or aren't feeling well. It is essential to continue Imuran as scheduled as long as it is tolerated and does not cause severe side effects.

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

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Food and Drug Administration. Imuran label.

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