Mefenamic Acid and Warfarin Interaction
Drug interaction information between Mefenamic Acid and Warfarin.
Mefenamic Acid and Warfarin have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Mefenamic Acid and Warfarin. 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
Mefenamic acid can increase the risk of bleeding when used with warfarin. These drugs work together to slow down blood clotting more than usual.
What To Do
Use this combination with caution and under a doctor's supervision. Your healthcare provider may need to change your medication plan.
Mefenamic Acid Also Interacts With
- Methotrexate moderate
- Diflunisal moderate
- Meloxicam minor
- Furosemide minor
- Aspirin minor
Warfarin Also Interacts With
- Fluoxetine major
- Tamoxifen major
- Ibuprofen moderate
- Aspirin moderate
- Diclofenac moderate
Frequently Asked Questions
Can I take Mefenamic Acid and Warfarin together?
This is a moderate interaction. Use this combination with caution and under a doctor's supervision. Your healthcare provider may need to change your medication plan.
How serious is the interaction between Mefenamic Acid and Warfarin?
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 Warfarin interact?
Mefenamic acid can increase the risk of bleeding when used with warfarin. These drugs work together to slow down blood clotting more than usual.
Understanding the Mefenamic Acid and Warfarin 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 Warfarin belongs to the Vitamin K Antagonist (Anticoagulant) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Mefenamic acid can increase the risk of bleeding when used with warfarin. 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 Warfarin has 163. 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: Use this combination with caution and under a doctor's supervision. 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 Warfarin 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.