What the FDA labels say about taking them together
Diflunisal and methotrexate
Diflunisal's FDA label of August 4, 2026 names methotrexate in its drug interactions section; methotrexate's label does not name diflunisal itself but warns about its class (NSAIDs (nonsteroidal anti-inflammatory drugs)).
Check it at the source: the diflunisal FDA label on DailyMed (effective August 4, 2026, Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc.); the methotrexate FDA label on DailyMed (effective May 27, 2026, Accord Healthcare Inc.).
What does the diflunisal label say about methotrexate?
Diflunisal label, drug interactionsMethotrexate NSAIDs have been reported to competitively inhibit methotrexate accumulation in rabbit kidney slices.
Source: FDA drug label (diflunisal), Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc., effective August 4, 2026 (SPL set 666f89b4-fd81-420a-a390-eb1cd4014f61), via openFDA; the full label on DailyMed
What does the methotrexate label say about diflunisal?
Methotrexate's label does not name diflunisal itself; it warns about its class (NSAIDs (nonsteroidal anti-inflammatory drugs)):
Methotrexate label, boxed warningUnexpectedly severe (sometimes fatal) bone marrow suppression, aplastic anemia, and gastrointestinal toxicity have been reported with concomitant administration of methotrexate (usually in high dosage) along with some nonsteroidal anti-inflammatory drugs (NSAIDs) [see Warnings and Precautions (5.1) and Drug Interactions(7.1) ].
Methotrexate label, drug interactionsConcomitant administration of some NSAIDs with high dose methotrexate therapy has been reported to elevate and prolong serum methotrexate levels, resulting in deaths from severe hematologic and gastrointestinal toxicity [see Warnings and Precautions (5.1) ].
Source: FDA drug label (Methotrexate), Accord Healthcare Inc., effective May 27, 2026 (SPL set 874c7f43-a3be-4236-89cc-24c44e3c5813), 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
| Diflunisal | Methotrexate | |
|---|---|---|
| Labeled for | Pain, Osteoarthritis, Rheumatoid arthritis | Rheumatoid arthritis, Psoriasis, Leukemia, lymphoma and myeloma, Breast cancer |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $1.06 per tablet 500 mg tablet | $0.158 per tablet 2.5 mg tablet |
| Shortage now | No current entry | In shortage |
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