What the FDA labels say about taking them together
Febuxostat and mercaptopurine
Febuxostat's FDA label of December 24, 2025 names mercaptopurine in its contraindications section; the mercaptopurine labels PlainMeds reads (2) do not name febuxostat. The febuxostat label: “CONTRAINDICATIONS ULORIC is contraindicated in patients being treated with azathioprine or mercaptopurine.”
Check it at the source: the febuxostat FDA label on DailyMed (effective December 24, 2025, Takeda Pharmaceuticals America, Inc.); the mercaptopurine FDA label on DailyMed (effective July 20, 2026, Nova Laboratories, Ltd).
What does the febuxostat label say about mercaptopurine?
Febuxostat label, contraindicationsCONTRAINDICATIONS ULORIC is contraindicated in patients being treated with azathioprine or mercaptopurine [see Drug Interactions (7) ].
Febuxostat label, drug interactionsDRUG INTERACTIONS Concomitant administration of ULORIC with XO substrate drugs, azathioprine or mercaptopurine could increase plasma concentrations of these drugs resulting in severe toxicity.
Source: FDA drug label (ULORIC), Takeda Pharmaceuticals America, Inc., effective December 24, 2025 (SPL set 54de10ef-fe5f-4930-b91d-6bbb04c664bd), via openFDA; the full label on DailyMed
What does the mercaptopurine label say about febuxostat?
Mercaptopurine's label (effective July 20, 2026) and its 1 other brand-application label do not name febuxostat in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (MERCAPTOPURINE), Nova Laboratories, Ltd, effective July 20, 2026 (SPL set 9c6fc66b-522f-499d-961a-cde6ca0ec2e5), 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
| Febuxostat | Mercaptopurine | |
|---|---|---|
| Labeled for | Gout | Leukemia, lymphoma and myeloma |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.191 per tablet 40 mg tablet | $1.07 per tablet 50 mg tablet |
| 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