Comprehensive medication guide to Imuran including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$5–$25 copay on most commercial and Medicare Part D plans; generic azathioprine is typically Tier 1–2 on most formularies. Prior authorization is generally not required for FDA-approved indications.
Estimated Cash Pricing
$13–$17 for generic azathioprine 50 mg (30 tablets) with GoodRx or SingleCare coupon; $40–$70 without a coupon for a 30-day supply. Brand Imuran and higher doses cost significantly more.
Medfinder Findability Score
65/100
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Imuran is the brand name for azathioprine, an immunosuppressant medication in the class of purine antimetabolites. It has been used in medicine since the 1960s and remains a cornerstone therapy for preventing organ transplant rejection and managing autoimmune conditions. It is available as a generic (multiple manufacturers) and as brand-name Imuran (50 mg tablets) and Azasan (75 mg and 100 mg tablets).
The FDA approved azathioprine in March 1968 for two indications: prevention of kidney transplant rejection and management of active rheumatoid arthritis. It is also widely used off-label for inflammatory bowel disease (Crohn's disease, ulcerative colitis), lupus nephritis, myasthenia gravis, autoimmune hepatitis, multiple sclerosis, psoriasis, pemphigus, vasculitis, and many other autoimmune and inflammatory conditions.
Azathioprine is not a controlled substance and does not require any DEA special prescribing authority. It is taken orally once or twice daily with food to reduce nausea, and it typically takes 6 to 12 weeks to reach its full therapeutic effect.
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Imuran (azathioprine) is a prodrug — meaning it has no activity until your body processes it. After you swallow the tablet, your body converts azathioprine into 6-mercaptopurine (6-MP), which is then further processed into thioguanine nucleotides (TGNs). TGNs are counterfeit purine building blocks that closely resemble the natural nucleotides your immune cells need to build DNA.
When T-cells and B-cells (the immune cells responsible for attacking transplanted organs or your own tissues in autoimmune disease) try to divide and multiply, they incorporate TGNs into their DNA. The resulting DNA is structurally flawed — like a brick wall built with counterfeit bricks — and the cell cannot complete division. This blunts the immune attack at the cellular level.
The enzyme TPMT (thiopurine S-methyltransferase) and the related enzyme NUDT15 are responsible for metabolizing azathioprine's active compounds. Patients with reduced or absent TPMT/NUDT15 activity accumulate higher TGN levels and are at risk for severe bone marrow suppression at standard doses — which is why genetic testing is recommended before starting therapy.
50 mg — tablet
Most common strength; available as brand Imuran and multiple generics. Taken once or twice daily with food.
75 mg — tablet
Available as brand Azasan. Less commonly prescribed.
100 mg — tablet
Available as brand Azasan. Used for higher-dose protocols.
100 mg/vial — injectable
Azathioprine sodium for IV use. Currently on FDA shortage list (Hikma back-ordered since late 2024). For inpatient and infusion use only.
The injectable formulation of azathioprine (100 mg vials) is on the FDA's official drug shortage list, with Hikma reporting back-order status since late 2024 and no estimated resolution date as of 2026. This primarily affects hospitals and infusion centers. The oral tablets (generic azathioprine 50 mg, Imuran, and Azasan) are not on the FDA's formal shortage list and continue to be manufactured by multiple generic companies.
However, oral tablet availability is uneven. Patients frequently report difficulty finding azathioprine at specific pharmacies due to wholesaler allocation patterns, a limited manufacturer base, and spillover from the injectable shortage (hospitals crushing oral tablets for patients who cannot swallow). The oral supply situation is better described as distribution unevenness than a true manufacturing deficit — the medication is being made, but not every pharmacy has it on hand at every moment.
Patients who plan refills 2-3 weeks in advance, request 90-day supplies, and use tools like medfinder to check pharmacy stock are best positioned to maintain uninterrupted therapy. Specialty pharmacies affiliated with transplant centers tend to stock azathioprine more reliably than general retail pharmacies.
Imuran (azathioprine) is not a controlled substance, so there are no DEA-related prescribing restrictions. Any licensed prescriber with authority to write prescriptions in their state can technically prescribe azathioprine. In practice, it is managed by specialists who monitor for its specific toxicities, particularly myelosuppression, hepatotoxicity, and malignancy risk.
Transplant nephrologists and transplant surgeons — for kidney transplant rejection prevention
Rheumatologists — for rheumatoid arthritis, lupus, myasthenia gravis, vasculitis
Gastroenterologists and hepatologists — for IBD and autoimmune hepatitis
Neurologists — for myasthenia gravis, multiple sclerosis, neuromyelitis optica
Dermatologists — for severe atopic dermatitis, pemphigus, bullous pemphigoid
Primary care physicians (PCPs), Nurse Practitioners (NPs), and Physician Assistants (PAs) — for ongoing management in stable, established patients
Telehealth is available for follow-up visits and prescription renewals in stable patients. Initial prescribing typically requires in-person specialist evaluation including TPMT/NUDT15 genetic testing, baseline CBC, liver function tests, and hepatitis screening.
No. Imuran (azathioprine) is not a controlled substance and is not scheduled by the Drug Enforcement Administration (DEA). It does not appear on any DEA drug schedule (I through V). There are no special federal prescribing restrictions, and pharmacies are not required to use special order forms or DEA tracking for azathioprine.
Azathioprine does require a valid prescription from a licensed prescriber — it is a prescription-only medication (Rx only). Standard prescription rules apply, including limits on refills without a new prescription in states with annual prescription expiration rules. However, none of these restrictions are more stringent than for any other non-controlled prescription medication.
The most common side effects of azathioprine include:
Nausea and vomiting (approximately 12% of RA patients in the first months of therapy)
Diarrhea and stomach upset
Fatigue
Mild hair thinning
Liver enzyme elevations (more common in transplant recipients)
Boxed Warning: Chronic immunosuppression with azathioprine increases the risk of malignancy, including post-transplant lymphoma and hepatosplenic T-cell lymphoma (HSTCL) in IBD patients.
Myelosuppression: leukopenia, thrombocytopenia, anemia — risk highest in TPMT/NUDT15-deficient patients
Serious infections due to immune suppression
Hepatotoxicity (rare in RA patients <1%; more common in transplant recipients)
Pancreatitis (rare hypersensitivity reaction)
Skin cancer and lymphoma (risk increases with duration of use and dose)
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Mycophenolate Mofetil (CellCept)
Preferred alternative for transplant and lupus nephritis. Also blocks purine synthesis (via IMPDH inhibition). Often better GI tolerability than azathioprine but absolutely contraindicated in pregnancy.
Methotrexate (Trexall, Rheumatrex)
First-line DMARD for rheumatoid arthritis. Blocks folate metabolism. Works faster than azathioprine (4-6 weeks). Typically tried before azathioprine for RA.
Mercaptopurine (Purinethol, 6-MP)
Active metabolite of azathioprine. Used for IBD and leukemia. Some patients who don't tolerate azathioprine tolerate 6-MP, and vice versa. Note: also in shortage in 2026.
Cyclosporine (Neoral, Sandimmune)
Calcineurin inhibitor used for transplant and autoimmune conditions. Different mechanism of action. More significant drug interactions and nephrotoxicity risk than azathioprine.
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Allopurinol (Zyloprim)
majorInhibits xanthine oxidase, blocking azathioprine metabolism. Coadministration requires azathioprine dose reduction to 1/4 to 1/3 of normal dose. Failure to reduce dose can cause life-threatening myelosuppression.
Febuxostat (Uloric)
majorSimilar mechanism to allopurinol — inhibits xanthine oxidase. Coadministration with azathioprine is generally contraindicated due to severe myelosuppression risk. Consult prescriber immediately if both are needed.
Ribavirin
majorInhibits IMDH enzyme, causing accumulation of toxic azathioprine metabolite (6-MTITP). Combination causes severe pancytopenia. Requires weekly CBC monitoring if combination is unavoidable.
Live vaccines (MMR, varicella, yellow fever, FluMist)
majorContraindicated. Azathioprine may reduce vaccine efficacy and could allow live attenuated organisms to cause disease in immunosuppressed patients.
ACE inhibitors (lisinopril, enalapril, captopril)
moderatePharmacodynamic synergism increases neutropenia and anemia risk. Monitor CBC more frequently when combined.
Warfarin (Coumadin)
moderateAzathioprine inhibits the anticoagulant effect of warfarin. Requires more frequent INR monitoring when azathioprine is initiated or dose is changed.
TNF blockers (infliximab, adalimumab, etanercept)
moderateCombination significantly increases risk of hepatosplenic T-cell lymphoma (HSTCL), particularly in young male IBD patients. Use requires very careful risk-benefit assessment.
Imuran (azathioprine) is a well-established immunosuppressant with more than 50 years of clinical use. It is affordable, widely prescribed across multiple specialties, and effective for a broad range of conditions. The oral tablet supply is generally adequate in 2026, though patients may need to search across multiple pharmacies to find it due to uneven distribution. The injectable formulation remains in shortage.
Patients on azathioprine should plan refills 2-3 weeks ahead, request 90-day supplies when possible, take the medication consistently with food, and never skip doses without talking to their doctor. Regular blood monitoring (CBC and LFTs) is essential for safe long-term use.
If you're struggling to find Imuran at your pharmacy, medfinder calls pharmacies near you to check which ones have it in stock — saving you time and helping ensure you never miss a dose.
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