Mefenamic Acid and Diflunisal Interaction
Drug interaction information between Mefenamic Acid and Diflunisal.
Mefenamic Acid and Diflunisal have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Mefenamic Acid and Diflunisal. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Taking these two drugs together increases the risk of stomach bleeding and ulcers without providing extra relief. Both drugs are similar and can irritate the lining of your digestive system.
What To Do
Avoid taking these two medications at the same time. Your doctor should help you choose just one of these drugs to manage your symptoms safely.
FDA Label Information
NSAIDs and Salicylates Clinical Impact: Concomitant use of mefenamic acid with other NSAIDs or salicylates (e.g., diflunisal, salsalate) increases the risk of GI toxicity, with little or no increase in efficacy (see Warnings ; Gastrointestinal Bleeding, Ulceration and Perforation ).
Mefenamic Acid Also Interacts With
- Methotrexate moderate
- Warfarin moderate
- Meloxicam minor
- Furosemide minor
- Aspirin minor
Diflunisal Also Interacts With
- Methotrexate moderate
- Cyclosporine moderate
- Celecoxib moderate
- Indomethacin moderate
- Meloxicam moderate
Frequently Asked Questions
Can I take Mefenamic Acid and Diflunisal together?
This is a moderate interaction. Avoid taking these two medications at the same time. Your doctor should help you choose just one of these drugs to manage your symptoms safely.
How serious is the interaction between Mefenamic Acid and Diflunisal?
This interaction is classified as "moderate" severity by the FDA. Moderate interactions may worsen your condition or change how your medications work.
Why do Mefenamic Acid and Diflunisal interact?
Taking these two drugs together increases the risk of stomach bleeding and ulcers without providing extra relief. Both drugs are similar and can irritate the lining of your digestive system.
Understanding the Mefenamic Acid and Diflunisal Interaction
FDA-approved prescribing information for these two drugs flags their combination as a moderate-severity interaction. Mefenamic Acid belongs to the Nonsteroidal Anti-Inflammatory Drug (NSAID) class and Diflunisal belongs to the Nonsteroidal Anti-Inflammatory Drug (NSAID) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Taking these two drugs together increases the risk of stomach bleeding and ulcers without providing extra relief. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Mefenamic Acid has 15 total documented interactions on file in this dataset, and Diflunisal has 17. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Avoid taking these two medications at the same time. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Mefenamic Acid or Diflunisal based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.