What Is Azasan?
Azasan is the brand name for azathioprine, an immunosuppressant medication that has been used in clinical practice since the 1960s. It belongs to the drug class of purine analogs and is classified as both an antirheumatic and an immunosuppressant. Azasan works by suppressing the immune system, which makes it effective for preventing organ rejection after transplant surgery and for treating autoimmune conditions where the body's immune system attacks its own tissues.
Azathioprine was first developed by George Hitchings and Gertrude Elion — work that eventually contributed to their Nobel Prize in Physiology or Medicine in 1988. Over the past six decades, it has become one of the most widely used immunosuppressive agents in the world, prescribed across multiple medical specialties.
Key Facts at a Glance
- Brand names: Azasan, Imuran
- Generic name: Azathioprine
- Drug class: Purine analog immunosuppressant; antirheumatic
- Manufacturer: Azasan is manufactured by Salix Pharmaceuticals (a Bausch Health company). Generic azathioprine is made by multiple manufacturers including Mylan, Zydus, Apotex, and others.
- FDA approval: Originally approved in 1968 for kidney transplant rejection prevention and rheumatoid arthritis
- Controlled substance: No — azathioprine is not a controlled substance
- Available forms: Oral tablets (50mg, 75mg, 100mg) and injectable solution
What Is Azasan Used For?
Azasan has two FDA-approved indications, plus a long list of well-established off-label uses. Here's what doctors prescribe it for:
FDA-Approved Uses
- Prevention of kidney transplant rejection: Azasan is used as part of a multi-drug immunosuppressive regimen to prevent your body's immune system from rejecting a transplanted kidney. It's typically started on or just before the day of transplant surgery and continued long-term.
- Rheumatoid arthritis (RA): For patients with active RA who haven't responded adequately to other treatments (like NSAIDs, methotrexate, or conventional DMARDs), Azasan can help reduce joint inflammation, pain, and swelling. It's considered a disease-modifying antirheumatic drug (DMARD).
Common Off-Label Uses
While not FDA-approved for these conditions, azathioprine is widely used and well-studied for:
- Inflammatory bowel disease (IBD): Both Crohn's disease and ulcerative colitis. Azathioprine is commonly used as a maintenance therapy to keep these conditions in remission and to reduce dependence on corticosteroids. It is recognized as a treatment option for Crohn's disease in children.
- Autoimmune hepatitis: Used alongside corticosteroids as a maintenance therapy to control liver inflammation.
- Systemic lupus erythematosus (SLE): Particularly for lupus nephritis (kidney involvement), where it helps control immune-mediated damage.
- Myasthenia gravis: As a steroid-sparing agent in severe cases where long-term immune suppression is needed.
- Multiple sclerosis: Sometimes used in resource-limited settings or when other disease-modifying therapies aren't tolerated.
- Autoimmune skin conditions: Including severe atopic dermatitis, psoriasis, pemphigus vulgaris, bullous pemphigoid, pyoderma gangrenosum, Behçet disease, and cutaneous vasculitis.
- Other conditions: Chronic immune thrombocytopenia (ITP), recurrent pericarditis, dermatomyositis/polymyositis, Churg-Strauss syndrome, non-infectious uveitis, relapsing polychondritis, and connective tissue disease-associated interstitial lung disease.
How Is Azasan Taken?
Understanding how to take Azasan correctly is important for both effectiveness and safety.
Dosage Forms
Azasan is available as oral tablets in 50mg, 75mg, and 100mg strengths. Generic azathioprine is available in 50mg tablets (the most common) and as a scored tablet that can be split for dose adjustments. An injectable form exists for intravenous use in hospital settings, but most patients take it orally.
Typical Dosing
- Kidney transplant rejection prevention: The typical starting dose is 3 to 5 mg/kg/day, beginning on the day of transplant or shortly before. The maintenance dose is usually 1 to 3 mg/kg/day, adjusted based on response and tolerability.
- Rheumatoid arthritis: The starting dose is approximately 1 mg/kg/day (50 to 100mg), which may be gradually increased over 6 to 8 weeks to a maximum of 2.5 mg/kg/day if the initial dose doesn't provide adequate relief and blood work remains normal.
- Off-label uses (IBD, autoimmune hepatitis, etc.): Typical dosing is 2 to 2.5 mg/kg/day, adjusted based on condition and individual response.
How to Take It
- Azasan can be taken with or without food, but taking it with food or right after a meal reduces nausea — the most common side effect.
- If your daily dose causes significant stomach upset, your doctor may recommend splitting it into two doses taken at different times of day.
- Take it at the same time each day for consistent blood levels.
- If you miss a dose, take it as soon as you remember — unless it's almost time for your next dose. Never double up.
- Do not crush, chew, or break the tablets unless your doctor or pharmacist specifically instructs you to.
Before Starting: Required Testing
Before your first dose of Azasan, your doctor should order:
- TPMT and NUDT15 genetic testing: These enzymes affect how your body processes azathioprine. People with low activity in these enzymes need lower doses — or may need a different medication entirely — because they're at much higher risk of severe bone marrow suppression.
- Baseline blood work: Complete blood count (CBC) and liver function tests (LFT) to establish your starting levels.
- Hepatitis B and C screening: Because Azasan suppresses the immune system, latent hepatitis B can reactivate dangerously.
- Pregnancy test: Azasan can harm an unborn baby, particularly when used for rheumatoid arthritis.
Who Should Not Take Azasan?
Azasan is not appropriate for everyone. The following are key contraindications:
- Allergy to azathioprine or mercaptopurine: Since azathioprine is converted to mercaptopurine (6-MP) in the body, an allergy to either medication is a contraindication.
- Pregnancy (for RA treatment): Azasan is contraindicated during pregnancy when used for rheumatoid arthritis. For other conditions like organ transplant or lupus, the risk-benefit calculation is different, and your doctor will help you decide.
- Breastfeeding: Azathioprine's metabolite (6-MP) passes into breast milk.
- Unknown or deficient TPMT/NUDT15 status: Starting Azasan without knowing your TPMT/NUDT15 enzyme activity puts you at high risk of life-threatening bone marrow suppression.
- Active, clinically significant infections: Because Azasan suppresses your immune system, active infections should be treated before starting the medication.
- Known malignancy: The medication's immunosuppressive effects could worsen certain cancers.
Additionally, use caution if you take allopurinol (for gout) — this combination requires a significant dose reduction of Azasan because allopurinol inhibits the enzyme that breaks down azathioprine, leading to dangerous accumulation. See our full guide on Azasan drug interactions.
How Much Does Azasan Cost?
The cost of Azasan varies significantly depending on whether you're buying brand-name or generic, your insurance coverage, and which pharmacy you use.
Without Insurance
- Generic azathioprine 50mg (30 tablets): Approximately $40 to $70 retail price at most pharmacies.
- With a coupon (GoodRx, SingleCare): As low as $11 to $15 for a 30-day supply of generic azathioprine 50mg.
- Brand-name Azasan: Typically $40 to $80+ per month, depending on dose and pharmacy.
- Higher doses (100mg tablets): Retail price around $464 for 100 tablets without a coupon. Coupons can reduce this significantly.
With Insurance
Generic azathioprine is on most insurance formularies, typically placed on Tier 1 or Tier 2 (preferred generics). Copays usually range from $5 to $30 per month. Brand-name Azasan may require higher copays or prior authorization.
For detailed savings strategies, see our guide on how to save money on Azasan in 2026.
Final Thoughts
Azasan (azathioprine) is a well-established immunosuppressant with over 60 years of clinical use. It's a critical medication for kidney transplant recipients and an important treatment option for patients with rheumatoid arthritis and numerous autoimmune conditions. While it requires careful monitoring — including genetic testing before starting and regular blood work throughout treatment — it remains one of the most effective and affordable immunosuppressive agents available.
If your doctor has recommended Azasan, make sure you understand the monitoring requirements, potential side effects, and drug interactions before starting. And when it's time to fill your prescription, Medfinder can help you find a pharmacy with Azasan in stock near you.
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