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Mefenamic Acid and Furosemide Interaction

Drug interaction information between Mefenamic Acid and Furosemide.

Mefenamic Acid and Furosemide have a documented minor interaction in FDA labeling.

FDA drug labeling documents a minor-severity interaction between Mefenamic Acid and Furosemide. 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.

Drug A

Mefenamic Acid

Nonsteroidal Anti-Inflammatory Drug (NSAID)

Drug B

Furosemide

Loop Diuretic

How They Interact

Mefenamic acid can block the effects of furosemide, making it harder for your body to remove extra salt and water through your urine.

What To Do

Your doctor may need to check your blood pressure and fluid levels more often while you are taking both drugs.

FDA Label Information

Diuretics Clinical Impact: Clinical studies, as well as post-marketing observations, showed that NSAIDs reduced the natriuretic effect of loop diuretics (e.g., furosemide) and thiazide diuretics in some patients.

Mefenamic Acid Also Interacts With

View all Mefenamic Acid interactions →

Frequently Asked Questions

Can I take Mefenamic Acid and Furosemide together?

This is a minor interaction. Your doctor may need to check your blood pressure and fluid levels more often while you are taking both drugs.

How serious is the interaction between Mefenamic Acid and Furosemide?

This interaction is classified as "minor" severity by the FDA. Minor interactions are unlikely to cause significant problems but should still be mentioned to your healthcare provider.

Why do Mefenamic Acid and Furosemide interact?

Mefenamic acid can block the effects of furosemide, making it harder for your body to remove extra salt and water through your urine.

Understanding the Mefenamic Acid and Furosemide Interaction

FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Mefenamic Acid belongs to the Nonsteroidal Anti-Inflammatory Drug (NSAID) class and Furosemide belongs to the Loop Diuretic class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Mefenamic acid can block the effects of furosemide, making it harder for your body to remove extra salt and water through your urine. 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 Furosemide has 36. 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: Your doctor may need to check your blood pressure and fluid levels more often while you are taking both drugs. 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 Furosemide 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.