Imuran Shortage: What Providers and Prescribers Need to Know in 2026

Azathioprine (Imuran, Azasan) availability in 2026 presents a mixed but manageable clinical challenge. The injectable formulation remains on the FDA shortage list, while oral tablets — the form used by the vast majority of outpatient prescribers — are not formally in shortage but continue to generate patient-level access problems. This guide synthesizes the current supply landscape, offers practical communication frameworks for affected patients, and outlines evidence-based alternatives by indication.

Current Supply Landscape

Injectable azathioprine sodium (100 mg vials): On the FDA Drug Shortage Database. Hikma, a primary manufacturer, placed vials on back order in late 2024 with no estimated resolution date as of early 2026. This affects inpatient transplant programs, post-operative patients, and anyone unable to take oral medications. Check the ASHP Drug Shortage Database regularly for updated manufacturer communications.

Oral azathioprine (50 mg generics, 75 mg and 100 mg Azasan brand): Not on the FDA shortage list. Multiple generic manufacturers continue to produce 50 mg tablets. However, distribution unevenness means individual pharmacy-level gaps are common. Patients report intermittent out-of-stock situations that vary significantly by region, pharmacy chain, and wholesaler allocation. The aggregate supply appears adequate, but local availability is inconsistent.

Clinical Implications by Patient Population

Renal transplant patients: Any gap in antiproliferative coverage carries rejection risk. Proactively review refill logistics with transplant patients at every visit. Consider prescribing 90-day supplies when clinically appropriate and formulary-permissive. For patients who cannot obtain oral azathioprine, mycophenolate mofetil (CellCept) or mycophenolate sodium (Myfortic) is the established alternative in most current transplant protocols.

Rheumatoid arthritis: Azathioprine is typically a second-line DMARD used after methotrexate failure or intolerance. For RA patients on azathioprine who cannot access it, a discussion about returning to methotrexate (if not previously tried), leflunomide, or biologic DMARDs is appropriate. Disease activity should guide urgency.

Inflammatory bowel disease (Crohn's, UC): Mercaptopurine (6-MP) is the closest pharmacological substitute — azathioprine is a prodrug of 6-MP. However, mercaptopurine itself is in shortage as of 2026. Mycophenolate mofetil or biologic agents (infliximab, adalimumab, vedolizumab) may be appropriate for moderate-to-severe IBD patients who cannot access thiopurines. For patients in remission on low doses, temporary corticosteroid bridging may be considered pending supply resolution.

Other autoimmune indications (lupus, myasthenia gravis, autoimmune hepatitis, vasculitis): Alternative selections are highly condition-specific. Mycophenolate mofetil has the most evidence as a substitute in lupus nephritis and autoimmune hepatitis. Methotrexate is well-studied for myasthenia gravis as a steroid-sparing agent. Rituximab is an option for refractory cases. Consult condition-specific guidelines when selecting alternatives.

TPMT and NUDT15 Testing Reminder

If your patients are starting azathioprine for the first time, TPMT and NUDT15 genotyping should be performed before initiation. Approximately 10% of patients have reduced enzyme activity requiring dose reduction, and approximately 0.3% have absent activity and are at risk for life-threatening myelosuppression at standard doses. This is standard of care. If genetic testing is not feasible before initiation, start at the lowest possible dose and escalate carefully with close CBC monitoring.

Key Drug Interactions to Flag at Prescribing

Allopurinol / Febuxostat: Inhibit XO, one of the inactivation pathways for azathioprine. Coadministration requires reduction of azathioprine dose to approximately 1/4 to 1/3 of standard dose. Failure to reduce is a leading cause of severe myelotoxicity.

Ribavirin: Inhibits IMDH, leading to accumulation of a toxic azathioprine metabolite (6-MTITP). Combination is associated with severe pancytopenia. Weekly CBC monitoring for the first month is required if coadministration is unavoidable.

ACE inhibitors: Pharmacodynamic synergism with azathioprine can increase neutropenia risk. Monitor CBC more frequently in patients on both agents.

Live vaccines: Contraindicated in patients on azathioprine. Review vaccination history before initiating therapy and ensure patients are up to date on inactivated vaccines before starting immunosuppression.

Patient Communication Strategies

Proactive communication reduces the risk of patients going without doses. Consider the following at each visit or refill:

Discuss refill logistics at every visit — ask patients how many pills they have left and whether their pharmacy has had stock issues.

Prescribe 90-day supplies when clinically appropriate and insurance allows.

Consider recommending mail-order pharmacy for patients who fill prescriptions less frequently — mail-order tends to stock immunosuppressants more reliably.

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Resources for Monitoring Shortage Status

FDA Drug Shortage Database: accessdata.fda.gov/scripts/drugshortages

ASHP Drug Shortage Database: ashp.org/drug-shortages

NeedyMeds.org and RxAssist.org for patient financial assistance referrals

For a deeper dive into supporting your patients through the access process, see our guide on how to help your patients find Imuran in stock. medfinder for providers helps your patients find their medication faster — consider recommending it at the point of prescribing.