What the FDA labels say about taking them together
Azathioprine and olsalazine
Azathioprine's FDA label of November 8, 2025 names olsalazine in its drug interactions section, and olsalazine's label names azathioprine too. The olsalazine label: “Azathioprine or 6-Mercaptopurine: Increased risk of blood dyscrasias; monitor complete blood cell counts and platelet counts.”
Check it at the source: the azathioprine FDA label on DailyMed (effective November 8, 2025, Sebela Pharmaceuticals Inc.); the olsalazine FDA label on DailyMed (effective May 15, 2026, Viatris Specialty LLC).
What does the azathioprine label say about olsalazine?
Azathioprine label, drug interactionsUse with Aminosalicylates: There is in vitro evidence that aminosalicylate derivatives (e.g., sulphasalazine, mesalazine, or olsalazine) inhibit the TPMT enzyme.
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 olsalazine label say about azathioprine?
Olsalazine label, drug interactionsAzathioprine or 6-Mercaptopurine: Increased risk of blood dyscrasias; monitor complete blood cell counts and platelet counts.
Source: FDA drug label (Dipentum), Viatris Specialty LLC, effective May 15, 2026 (SPL set 8512d0c6-db4e-4673-b3b4-28975c18413f), 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 | Olsalazine | |
|---|---|---|
| Labeled for | Organ transplant rejection, Rheumatoid arthritis | Crohn's disease and ulcerative colitis |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.124 per tablet 50 mg tablet | $15.70 per capsule 250 mg capsule |
| Shortage now | No current entry | No current entry |
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