What the FDA labels say about taking them together
Azathioprine and melphalan
Azathioprine's FDA label of November 8, 2025 names melphalan in its contraindications section; the melphalan labels PlainMeds reads (4) do not name azathioprine. The azathioprine label: “Patients with rheumatoid arthritis previously treated with alkylating agents may have a prohibitive risk of malignancy if treated with IMURAN.”
Check it at the source: the azathioprine FDA label on DailyMed (effective November 8, 2025, Sebela Pharmaceuticals Inc.); the melphalan FDA label on DailyMed (effective July 7, 2026, Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc.).
What does the azathioprine label say about melphalan?
Azathioprine label, contraindicationsPatients with rheumatoid arthritis previously treated with alkylating agents (cyclophosphamide, chlorambucil, melphalan, or others) may have a prohibitive risk of malignancy if treated with IMURAN.
Source: FDA drug label (IMURAN), NDA016324 (Legacy), as published by Sebela Pharmaceuticals Inc., effective November 8, 2025 (SPL set 606101a0-6244-7eff-e053-2a91aa0acadd), via openFDA; the full label on DailyMed
What does the melphalan label say about azathioprine?
Melphalan's label (effective July 7, 2026) and its 3 other brand-application labels do not name azathioprine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Melphalan hydrochloride), Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc., effective July 7, 2026 (SPL set 2c18beeb-7bd4-4591-94cb-9d7156c1b8e0), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Azathioprine | Melphalan | |
|---|---|---|
| Labeled for | Organ transplant rejection, Rheumatoid arthritis | Leukemia, lymphoma and myeloma |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.124 per tablet 50 mg tablet | n/a |
| Shortage now | No current entry | A presentation being discontinued |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once