What the FDA labels say about taking them together
Diflunisal and oxaprozin
Oxaprozin's FDA label of December 26, 2024 names diflunisal in its drug interactions section; diflunisal's label does not name oxaprozin itself but warns about its class (NSAIDs (nonsteroidal anti-inflammatory drugs)). The oxaprozin label: “Concomitant use of oxaprozin with other NSAIDs or salicylates increases the risk of GI toxicity, with little or no increase in efficacy.”
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 oxaprozin FDA label on DailyMed (effective December 26, 2024, Amneal Pharmaceuticals NY LLC).
What does the diflunisal label say about oxaprozin?
Diflunisal's label does not name oxaprozin itself; it warns about its class (NSAIDs (nonsteroidal anti-inflammatory drugs)):
Diflunisal label, boxed warningGastrointestinal Risk NSAIDs cause an increased risk of serious gastrointestinal adverse events including bleeding, ulceration, and perforation of the stomach or intestines, which can be fatal.
Diflunisal label, warningsGastrointestinal Effects – Risk of Ulceration, Bleeding and Perforation NSAIDs, including diflunisal tablets, can cause serious gastrointestinal (GI) adverse events including inflammation, bleeding, ulceration, and perforation of the stomach, small intestine, or large intestine, which can be fatal.
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 oxaprozin label say about diflunisal?
Oxaprozin label, drug interactionsNSAIDs and Salicylates Clinical Impact: Concomitant use of oxaprozin with other NSAIDs or salicylates (…) increases the risk of GI toxicity, with little or no increase in efficacy. Intervention: The concomitant use of oxaprozin with other NSAIDs or salicylates is not recommended.
Source: FDA drug label (Oxaprozin, NDA217927), SOLA Pharmaceuticals, LLC, effective December 3, 2025 (SPL set 450f5941-7f10-42fe-e063-6394a90a4803), via openFDA
Source: FDA drug label (Oxaprozin), Amneal Pharmaceuticals NY LLC, effective December 26, 2024 (SPL set d9b0ca6c-4c53-4f6e-918b-02a8c472a194), 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 | Oxaprozin | |
|---|---|---|
| Labeled for | Pain, Osteoarthritis, Rheumatoid arthritis | Osteoarthritis, Rheumatoid arthritis |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $1.06 per tablet 500 mg tablet | $0.475 per tablet 600 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