Mefenamic Acid and Anisindione: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Mefenamic Acid
Anisindione
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of bleeding
Interaction Deep Dive
Mefenamic acid appears to displace coumarin anticoagulants from protein binding sites, thereby increasing anticoagulant activity1. When concurrent mefenamic acid and oral anticoagulant therapy is used, frequent monitoring of the prothrombin time (PT) is necessary 2.
Why it happens (mechanism)
Inhibition of platelet aggregation, gastric erosion
Common questions
Can I take Mefenamic Acid and Anisindione together?
An increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Mefenamic Acid and Anisindione interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Mefenamic Acid or Anisindione need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (2)
- Diana FJ, Veronich K, & Kapoor AL: Binding of nonsteroidal anti-inflammatory agents and their effect on binding of racemic warfarin and its enantiomers to human serum albumin. J Pharm Sci 1989; 78:195-199. PubMed
- Product Information: Ponstel(R), mefenamic acid. Parke-Davis, Morris Plains, NJ, 1994. DailyMed
Keep reading about Mefenamic Acid
Keep reading about Anisindione
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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