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Imuran

Last reviewed on RxList: 1/13/2017
Imuran Side Effects Center

Last reviewed on RxList 9/16/2016

Imuran (azathioprine) is an immunosuppressive antimetabolite used to prevent the body from rejecting a transplanted kidney. Imuran is also used to treat symptoms of rheumatoid arthritis. Imuran is available in generic form. Common side effects of Imuran include:

  • upset stomach,
  • nausea,
  • vomiting,
  • diarrhea,
  • loss of appetite,
  • hair loss, or
  • skin rash.

Tell your doctor if you experience unlikely but serious side effects of Imuran including:

  • muscle loss,
  • hair loss,
  • cold/numbness in the fingers,
  • mouth sores,
  • difficult/painful swallowing, or
  • greasy stools.

The dose of Imuran to prevent transplant rejection and minimize toxicity varies. The initial dose is usually 3 to 5 mg/kg daily, beginning at the time of transplant. It is usually given as a single daily dose on the day of, and in some cases 1 to 3 days before, transplantation. Maintenance levels of 1 to 3 mg/kg daily are usually possible. For rheumatoid arthritis, the initial dose is approx. 1.0 mg/kg (50 to 100 mg) given as a single dose or twice-daily. Maximum dose is 2.5 mg/kg per day. Imuran may interact with allopurinol, mercaptopurine, methotrexate, blood thinners, cyclosporine, olsalazine, sulfasalazine, sulfamethoxasole, trimethoprim, or ACE inhibitors. Tell your doctor all medications you use. Imuran is not recommended for use during pregnancy. It may harm a fetus. Men and women should use two forms of birth control (e.g., condoms, birth control pill) while taking this medication. This medication can decrease the effectiveness of intrauterine devices (IUDs). Talk to your doctor about birth control. This medication passes into breast milk and may have undesirable effects on a nursing infant. Breastfeeding while using this drug is not recommended.

Our Imuran (azathioprine) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Imuran Consumer Information

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using azathioprine and call your doctor right away if you have any of these symptoms of lymphoma:

  • fever, night sweats, weight loss, tiredness;
  • feeling full after eating only a small amount;
  • pain in your upper stomach that may spread to your shoulder;
  • easy bruising or bleeding, pale skin, feeling light-headed or short of breath, rapid heart rate; or
  • nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Stop using azathioprine and call your doctor at once if you have any of these other serious side effects:

  • signs of infection (fever, chills, sore throat, body aches, weakness, muscle pain, flu symptoms);
  • severe nausea, vomiting, or diarrhea;
  • pain or burning with urination; or
  • white patches or sores inside your mouth or on your lips.

Less serious side effects may include:

  • mild upset stomach, nausea, diarrhea, loss of appetite;
  • hair loss; or
  • skin rash.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Imuran (Azathioprine)

Imuran Professional Information

SIDE EFFECTS

The principal and potentially serious toxic effects of IMURAN are hematologic and gastrointestinal. The risks of secondary infection and malignancy are also significant (see WARNINGS). The frequency and severity of adverse reactions depend on the dose and duration of IMURAN as well as on the patient's underlying disease or concomitant therapies. The incidence of hematologic toxicities and neoplasia encountered in groups of renal homograft recipients is significantly higher than that in studies employing IMURAN for rheumatoid arthritis. The relative incidences in clinical studies are summarized below:

Toxicity Renal Homograft Rheumatoid Arthritis
Leukopenia (any degree) > 50% 28%
   < 2500 cells/mm³ 16% 5.30%
  Infections 20% < 1%
Neoplasia *
  Lymphoma 0.50%  
  Others 2.80%  
* Data on the rate and risk of neoplasia among persons with rheumatoid arthritis treated with azathioprine are limited. The incidence of lymphoproliferative disease in patients with RA appears to be significantly higher than that in the general population. In one completed study, the rate of lymphoproliferative disease in RA patients receiving higher than recommended doses of azathioprine (5 mg/kg per day) was 1.8 cases per 1000 patient-years of follow-up, compared with 0.8 cases per 1000 patient-years of follow-up in those not receiving azathioprine. However, the proportion of the increased risk attributable to the azathioprine dosage or to other therapies (i.e., alkylating agents) received by patients treated with azathioprine cannot be determined.

Hematologic

Leukopenia and/or thrombocytopenia are dose-dependent and may occur late in the course of therapy with IMURAN. Dose reduction or temporary withdrawal may result in reversal of these toxicities. Infection may occur as a secondary manifestation of bone marrow suppression or leukopenia, but the incidence of infection in renal homotransplantation is 30 to 60 times that in rheumatoid arthritis. Anemias, including macrocytic anemia, and/or bleeding have been reported.

TPMT genotyping or phenotyping can help identify patients with low or absent TPMT activity (homozygous for non-functional alleles) who are at increased risk for severe, life-threatening myelosuppression from IMURAN. See CLINICAL PHARMACOLOGY, WARNINGS and PRECAUTIONS: Laboratory Tests. Death associated with pancytopenia has been reported in patients with absent TPMT activity receiving azathioprine.6,20

Gastrointestinal

Nausea and vomiting may occur within the first few months of therapy with IMURAN, and occurred in approximately 12% of 676 rheumatoid arthritis patients. The frequency of gastric disturbance often can be reduced by administration of the drug in divided doses and/or after meals. However, in some patients, nausea and vomiting may be severe and may be accompanied by symptoms such as diarrhea, fever, malaise, and myalgias (see PRECAUTIONS). Vomiting with abdominal pain may occur rarely with a hypersensitivity pancreatitis. Hepatotoxicity manifest by elevation of serum alkaline phosphatase, bilirubin, and/or serum transaminases is known to occur following azathioprine use, primarily in allograft recipients. Hepatotoxicity has been uncommon (less than 1%) in rheumatoid arthritis patients. Hepatotoxicity following transplantation most often occurs within 6 months of transplantation and is generally reversible after interruption of IMURAN. A rare, but life-threatening hepatic veno-occlusive disease associated with chronic administration of azathioprine has been described in transplant patients and in one patient receiving IMURAN for panuveitis.21,22,23 Periodic measurement of serum transaminases, alkaline phosphatase, and bilirubin is indicated for early detection of hepatotoxicity. If hepatic veno-occlusive disease is clinically suspected, IMURAN should be permanently withdrawn.

Others

Additional side effects of low frequency have been reported. These include skin rashes, alopecia, fever, arthralgias, diarrhea, steatorrhea, negative nitrogen balance, reversible interstitial pneumonitis, hepatosplenic T-cell lymphoma (see WARNINGS - Malignancy), and Sweet's Syndrome (acute febrile neutrophilic dermatosis).

Read the entire FDA prescribing information for Imuran (Azathioprine)

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