Imuran

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Imuran

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Medically reviewed

Marina Burgos

Last updated on 10/01/2026

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Imuran

Imuran is the brand name for the active substance Azathioprine, a powerful, synthetic medication used primarily to control and reduce the activity of the body’s immune system. Its core classification is as an immunosuppressant, designed for fundamental therapy in conditions requiring managed immune activity.

Quick Facts about Azathioprine

Property Description
Active ingredient Azathioprine (Azathioprina)
Form Oral tablet, Powder for injection
Pharmacological class Immunosuppressant, Antimetabolite
Origin Synthetic compound (Prodrug)

Identity and Pharmacological Classification

Azathioprine is a specialized, synthetic organic compound that belongs to the antimetabolite class of drugs, specifically a purine antimetabolite. It functions as a prodrug, meaning the molecule must be converted internally to become pharmacologically active, primarily to 6-mercaptopurine. This classification is vital as it establishes the drug's mechanism of action: directly interfering with the building blocks necessary for cell proliferation. Azathioprine is categorized as an essential medicine, a status that is clinically recognized for its established role in long-term immune management, a critical function often studied in pharmacological research.

Composition, Forms, and General Purpose

As a synthetic compound, Azathioprine is manufactured for patient use in two key dosage forms: the common oral tablet and a sterile powder for injection for intravenous administration. This dual-form availability is a distinguishing feature, ensuring therapeutic consistency for patients requiring chronic immunosuppression. It is designated as an immunosuppressive agent for the prevention of organ rejection and the management of autoimmune conditions. This controlled suppression is primarily utilized for adult patients to prevent the immune system from attacking a new organ or from targeting the body's own healthy tissues in severe autoimmune diseases. The medicine is strictly prescription-only (Rx), underscoring its potency and the need for ongoing medical supervision.

Regulatory References

  1. List of Essential Medicines
  2. MedlinePlus Drug Information

What side effects are possible with Imuran?

Possible Side Effects and Safety Information

Imuran (azathioprine) is an immunosuppressive drug, and its use is associated with a risk of serious adverse effects primarily related to the suppression of the immune and hematopoietic systems.

Serious and Clinically Significant Adverse Reactions

  • Malignancy Risk: Chronic immunosuppression significantly increases the risk of developing lymphoma (including the rare, aggressive Hepatosplenic T-cell lymphoma (HSTCL)), skin cancer, and other solid tumors. Patients are advised to limit exposure to sunlight and UV light.
  • Myelosuppression: The drug can cause severe bone marrow suppression, leading to dose-related, potentially life-threatening conditions such as leukopenia (low white blood cells), thrombocytopenia (low platelets), and anemia. Regular, close monitoring of blood counts is mandatory, especially during the initial months of treatment or following dose changes.
  • Serious Infections: The lowered immune response increases susceptibility to severe infections, including viral (e.g., severe chickenpox, shingles), fungal, and bacterial infections, and the rare, fatal brain infection Progressive Multifocal Leukoencephalopathy (PML).
  • Hepatotoxicity: Liver damage, which may be acute or lead to chronic conditions like nodular regenerative hyperplasia, is a documented risk. Liver function tests must be monitored regularly.

Common and Other Adverse Reactions

Nausea and vomiting are very common adverse reactions, particularly when initiating therapy, and may be dose-dependent. Other reported effects include fever, rash, pancreatitis, and gastrointestinal hypersensitivity reactions.

Safety Considerations and Restrictions

  • Contraindications: Imuran should not be used in patients with a known hypersensitivity to the drug. Use for rheumatoid arthritis is contraindicated in pregnant women.
  • Genetic Risk: Individuals with reduced or absent activity of the enzyme Thiopurine Methyltransferase (TPMT) are at a significantly increased risk of severe, life-threatening myelotoxicity if given conventional doses. TPMT testing is suggested before treatment initiation.
  • Vaccines: Administration of live vaccines is generally avoided due to the risk of a subnormal response or disseminated infection in immunosuppressed patients.

The regulatory safety profile mandates strict patient monitoring, as the most serious risks (myelotoxicity and malignancy) are inherent to the drug’s immunosuppressive mechanism.

Overdose and Emergency Response

Overdose and When to Seek Help

The most serious effect of an Imuran (azathioprine) overdose is bone marrow suppression, which may be delayed, with the lowest point (nadir) of cell counts occurring approximately nine to nineteen days after the dose. Signs of severe bone marrow suppression can include ulceration of the throat, fever, infections, unusual bruising, bleeding, or excessive fatigue.

A chronic minor overdose (e.g., due to a sustained incorrect dose) is considered more likely to cause toxicity than a single large ingestion. Given the availability of multiple tablet strengths, there is a risk of overdose if the wrong dose is prescribed or dispensed.

Required Emergency Actions

If an overdose is suspected or confirmed, you must contact a health care practitioner, a hospital emergency department, or a regional Poison Control Centre immediately, even if no symptoms are present.

There is no specific antidote for azathioprine overdose. Management involves careful monitoring of blood count and hepatic (liver) function. In severe cases of overdose or toxicity, azathioprine is dialysable, meaning dialysis may be used to help remove the drug from the body. Hematologic improvement, though delayed, usually begins around the twelfth day after the overdose, provided no further high doses were taken.

Therapeutic Uses of Imuran

What Imuran Treats: Main Uses and Benefits

Imuran (Azathioprine) is commonly used in therapeutic contexts to manage severe conditions driven by an overactive immune system. Its core therapeutic benefit supports sustained immune control to ease challenging symptoms and address symptoms related to inflammatory or irritative states. The medication is utilized across a wide range of therapeutic domains.


Supporting Organ Transplant and Autoimmune Management

Imuran is commonly used in situations involving a transplanted organ, where it is applied across domains where additional symptomatic support is needed. It is also applied in conditions marked by chronic, active inflammation, including severe active Rheumatoid Arthritis, Systemic Lupus Erythematosus (SLE), and inflammatory bowel diseases like Crohn’s Disease and Ulcerative Colitis. It helps address symptom clusters that may become intense or disruptive, such as symptoms related to physical discomfort and systemic imbalance.

The medication is generally considered relevant in clinical settings that involve acute or unstable symptom patterns in severe and refractory disease states. The support provided may contribute to maintaining a period of improved functional stability. This may assist with managing the intensity of symptoms that become more disruptive during flare-ups and contributes to easing the overall symptom load.


Quick Fact: Managing Symptoms Related to Systemic Imbalance
Imuran is often applied in scenarios where additional management of discomfort is required, providing support that helps patients cope more steadily with difficult episodes by easing distress.

Eligibility and Restrictions for Use

Who Can and Cannot Use Imuran? (Azathioprine)

Imuran, which contains the active ingredient azathioprine, is an immunosuppressant medication used primarily to prevent organ rejection following a kidney transplant and to treat symptoms of severe rheumatoid arthritis (RA) in adults. It may also be prescribed for other autoimmune diseases like inflammatory bowel disease (Crohn's disease or ulcerative colitis).


Contraindications and Precautions

Imuran is not suitable for everyone. Do not use Imuran if you have a known allergy to azathioprine or any of its components.

Patients with certain underlying conditions or taking specific medications must use Imuran with extreme caution or avoid it entirely. This includes individuals with:

  • Pregnancy and Breastfeeding: Azathioprine can harm an unborn baby and pass into breast milk.
  • Severe infection: Due to its immunosuppressive action, it can worsen an existing severe infection.
  • Certain liver or bone marrow disorders.
  • Concurrent use with allopurinol: This combination significantly increases azathioprine levels, requiring a major dose adjustment or alternative treatment.

What should I know about interactions with other medicines?

Interactions with other medicines and products

The interaction profile of Imuran (Azathioprine) details specific, officially documented restrictions regarding co-administration with other medicines and substances.

Contraindicated and Restricted Combinations

Co-administration with Febuxostat is formally contraindicated due to the significant risk of toxicity resulting from increased plasma concentrations of the active metabolite. Immunization using any live organism vaccine is prohibited for patients taking Azathioprine due to the associated risk of infection in an immunocompromised state.

Pharmacokinetic and Pharmacodynamic Effects

Official regulatory information describes interactions that alter drug exposure. Allopurinol and other Xanthine Oxidase inhibitors block a major metabolic inactivation pathway, a pharmacokinetic interaction that necessitates a substantial dose reduction of Azathioprine. The label also notes that Azathioprine may inhibit the anticoagulant effect of Warfarin.

Additive myelosuppressive effects are documented with other agents, including Cotrimoxazole (Sulphamethoxazole/Trimethoprim), which carries a documented risk of severe hematological toxicity.

Food and Population-Specific Notes

The label includes a timing-separation rule: Azathioprine tablets must be taken at least 1 hour before or 2 hours after consuming milk or dairy products, as co-ingestion may lower systemic exposure. Additionally, individuals with an inherited TPMT or NUDT15 enzyme deficiency are officially documented to have a significantly increased risk of life-threatening myelotoxicity.

Mechanism of Action

Azathioprine's mechanism is defined by its function as a prodrug and a purine antimetabolite, which fundamentally interferes with the process of proliferation in immune cells.

The drug is inactive until converted into its working form, 6-Thioguanine Nucleotides (6-TGNs), through a necessary series of enzymatic steps. These 6-TGNs act as false substrates, inhibiting key enzymes required for the de novo synthesis of purine bases and mistakenly incorporating into the DNA and RNA of highly proliferative cells. This action limits the available genetic building blocks and damages cellular material.

By disrupting DNA and RNA synthesis, the mechanism primarily targets T- and B-lymphocytes, the rapidly expanding cells of the adaptive immune system. The combined antiproliferative effect and the induction of programmed cell death (apoptosis) in these lymphocytes causes a reduction in their population. This physiological outcome is the modulation of systemic inflammatory and immune pathways.

The rate of metabolism and resulting physiological effects are constrained by individual genetic variations. Enzymes like Thiopurine S-methyltransferase (TPMT) and Nucleotide Diphosphatase (NUDT15) control the inactivation of the active 6-TGNs, determining the intracellular concentration of the drug and, consequently, the degree of resulting immunosuppression.

Dosage and Administration Information

How Imuran is Used: Administration Guidelines

Imuran (Azathioprine) is used following structured, weight-based protocols. The medicine is primarily administered via the oral route as a tablet, but a sterile powder for intravenous (IV) injection is also an approved route when oral intake is not feasible.

Dosage Regimen and Frequency

Administration is dose-adjusted based on body weight, expressed as milligrams per kilogram (mg/kg) per day. For organ transplant recipients, the initial dose may be up to 5 mg/kg/day, with the maintenance dose reduced to a range of 1 to 3 mg/kg/day. For the management of other conditions (e.g., Rheumatoid Arthritis), the usual starting dose is 1.0 mg/kg/day, with a maximum established at 2.5 mg/kg/day.

The total daily dose is typically taken once a day or may be taken in divided doses (e.g., twice daily). Oral tablets are generally taken with or after food to help manage gastrointestinal tolerance.

Dosing Adjustments and Duration

Dose adjustments are established for certain populations and co-administered drugs:

Population/Condition Dosing Instruction
Renal/Hepatic Impairment Dosage is typically given at the lower end of the established range.
Older Adults Recommended dosages are at the lower end of the dose range.
Concomitant Allopurinol The Azathioprine dose is reduced to one-quarter (25%) of the original dose.

For transplant recipients, treatment is typically maintained indefinitely to prevent rejection, even if only low doses are necessary. For other conditions, a minimum trial duration, such as 12 weeks, is specified before treatment response is assessed.

Recent Clinical Evidence

Research evidence / Overview of Studies for Imuran (Azathioprine)

This overview summarizes the structure and nature of the official research evidence for Azathioprine, focusing on the types of studies conducted, the outcomes measured, and the recognized knowledge gaps, without offering clinical guidance.


Evidence for Use in Organ Transplantation

The use of Azathioprine was studied for its role in research exploring the management of the body’s immune response following a kidney transplant. Early Randomized Controlled Trials (RCTs) and long-term observational studies provided the foundation for its role in this area. Patient groups who received the medicine as part of a regimen that also included corticosteroids and other immunosuppressants was observed in these studies.

Research monitored measures of outcomes related to patient status, outcomes related to transplanted organ status (function of the transplanted organ), and the frequency and severity of acute rejection episodes. Findings describe patterns observed in the studies, including the documentation of patient-reported experiences and outcomes monitored over time.

Research highlights what is known, but there are limitations. The evidence largely reflects older, established regimens used decades ago. Studies comparing Azathioprine directly to the newest classes of immunosuppressants currently used for maintenance therapy are limited. Therefore, while the historical role is documented, the results apply only to the populations studied and the protocols they received at that time.


Evidence for Use in Autoimmune Diseases

This area synthesizes research into Azathioprine's role in the management of key autoimmune conditions involving periods of heightened symptoms. These studies monitored outcomes linked to inflammatory or irritative states and outcomes related to physical discomfort.

Study Designs for IBD and Rheumatoid Arthritis

For Crohn’s Disease and Ulcerative Colitis, research consists of RCTs and numerous comprehensive Systematic Reviews and Meta-analyses. These studies was evaluated in adults with moderate to severe disease, examining outcomes related to outcomes reflecting a phase of stability and outcomes related to the tapering of corticosteroid use. Findings indicate an observed slow onset in the research setting, sometimes taking 12 weeks or more before changes were measured.

Research in Systemic Lupus Erythematosus

Research in Systemic Lupus Erythematosus (SLE), particularly focusing on severe symptoms like Lupus Nephritis (kidney inflammation), was studied for its role in controlled trials and cohort studies. Researchers examined outcomes related to global disease activity scores and the long-term impact on renal function parameters. Studies report observations regarding the use of Azathioprine for outcomes related to management over time after initial treatment with more intense regimens. Research contributes to understanding symptom patterns, but some of the early controlled studies had sample sizes that were modest, and limited information is available from trials directly comparing Azathioprine to the newest biologic therapies approved for SLE.

Key Studies & References

  1. Azathioprine - StatPearls - NCBI Bookshelf (Summary of Indications and Mechanisms)
  2. Azathioprine and 6-mercaptopurine in Crohn disease. A meta-analysis (Feagan et al., 1996)
  3. Mycophenolate mofetil decreases acute rejection and may improve graft survival in renal transplant recipients when compared with azathioprine: a systematic review (Knight et al., 2009)
  4. Comparative Analysis of Adverse Effects and Graft Rejection Rates of Azathioprine versus Mycophenolate in Kidney Transplant Recipients (Illustrates use in maintenance therapy and comparative data)
  5. American College of Rheumatology Guideline for the Screening and Treatment of Lupus Nephritis (Reflects use in SLE/Lupus Nephritis, often for maintenance)

Frequently Asked Questions (FAQ)

Common questions about Imuran (FAQ)


Q: Is it common to feel more tired when starting Imuran?

Official documents list unusual tiredness or weakness as a symptom that patients should monitor. If this symptom is experienced, particularly when accompanied by other signs of potential toxicity or infection (e.g., fever, chills), it is recommended that a healthcare professional be contacted or consulted.


Q: Do hair loss or changes in hair texture happen with Imuran?

Regulatory product information reports hair loss (alopecia) as an adverse reaction documented in post-marketing experience and clinical trials. Official information indicates that this effect is more commonly observed in patients who are receiving the medication for organ transplant.


Q: Does alcohol interact with Imuran?

The official guidance from regulatory authorities advises patients to discuss the use of alcohol with their healthcare professional. This is because possible interactions or additive risks may occur when combining alcohol with certain medications, and consultation with a medical professional is generally indicated to assess the individual risk.


Q: What happens if a dose of Imuran is missed?

Regulatory patient guidance generally outlines a procedure for a missed dose, which typically involves taking the dose when remembered, unless it is almost time for the next scheduled dose. Patients are instructed never to take a double dose to compensate for a missed one, and consulting a healthcare provider is recommended if multiple doses are missed.


Q: What research is available about Imuran for autoimmune hepatitis?

Studies and specialist regulatory information indicate that Azathioprine is a component of therapy used to manage inflammation in the liver caused by autoimmune hepatitis. Research reports that its use may be associated with reduced requirements for steroid treatment over time.


Q: Does Imuran interfere with birth control pills?

Official safety information states that Azathioprine does not affect the function of hormonal birth control, such as contraceptive pills. Despite this, regulatory guidelines often include a recommendation for men and women to use two effective forms of contraception while on this medicine.


Q: How does Imuran affect fertility in men?

Regulatory product information notes that use is often discouraged for male patients intending to father a child, and specific medical guidance should be sought. Adequate contraceptive precautions are advised for men while taking the medication due to potential risk described in regulatory documents.


Q: Are there specific symptoms that require immediate medical attention while on Imuran?

Yes, regulatory patient guidance lists specific symptoms that may signal potential toxicity or severe infection and require immediate medical attention. These include fever, chills, sore throat, severe nausea or vomiting, unusual bleeding or bruising, or yellowing of the skin or eyes (jaundice).


Q: Is it okay to use herbal supplements while taking Imuran?

Regulatory information advises patients to tell their doctor about all prescription and over-the-counter medicines, vitamins, and herbal products being used. This practice is often advised because it helps the healthcare team track all substances that could potentially interact with the prescribed medication.


Q: What happens if I stop taking Imuran suddenly?

Official guidance emphasizes that patients should avoid discontinuing Imuran or changing their dose without prior consultation with their prescribing doctor. Any cessation or modification of the dose must be medically supervised.


Q: Does Imuran affect blood pressure?

Regulatory documents have reported low blood pressure (hypotension) as an adverse event associated with the use of this medicine. This effect is generally documented as a rare occurrence.


Q: Can Imuran affect dental procedures or healing?

Official patient guidance suggests informing their dentist about the use of Imuran. This is because certain dental work may need to be completed before or delayed until the patient's blood cell counts are confirmed to be within a safe range, as monitored by their healthcare team.


Q: Is it safe to drive while taking Imuran?

Regulatory product information states that caution should be exercised when driving or operating machinery. This caution is advised until the individual is certain of how the medicine affects them personally and if they experience any adverse effects that could impair their abilities.


Q: What are the signs of a drug interaction with Imuran?

The observable signs of a severe drug interaction often manifest as symptoms of toxicity in the body. This may include symptoms related to severe bone marrow suppression, such as unusual bleeding or bruising, or signs of liver damage, such as yellowing of the skin or eyes.


Q: Is Imuran ever prescribed to children?

Yes, the official regulatory label includes specific dosing information for children, primarily in the context of organ transplant cases. It is referenced in pediatric use sections of product information as a potent immunosuppressant when medically necessary.


Q: What ingredients are in the Imuran tablet?

Regulatory prescribing information describes the composition of the tablet. The active component is the drug azathioprine (50 mg), and the tablet also contains inactive ingredients like lactose, magnesium stearate, potato starch, povidone, and stearic acid.

How should Imuran be stored and disposed of?

How to Store and Dispose of Imuran (Azathioprine)

Official labeling requires specific conditions for the storage and disposal of Imuran tablets.


Storage Requirements

Condition Requirement
Temperature Store at Controlled Room Temperature, typically 20 to 25 C (68 to 77 F).
Protection Tablets must be kept protected from light and moisture and stored in a tight, light-resistant container.
Stability Keep all medicine, including the unused IV solution, which is stable for 24 hours after preparation, out of the reach of children.

Disposal Instructions

Due to its classification as an antimetabolite, azathioprine must be handled and disposed of according to guidelines for hazardous or cytotoxic drugs. Disposal must adhere to all applicable Federal, State, and local laws, utilizing approved specialized waste channels rather than household trash or wastewater systems.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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