diflunisal vs mefenamic acid
PlainMeds reviewed this comparison against our methodology in August 2026. It places FDA and CMS record fields side by side, without recommending either medication.
Side-by-side comparison of diflunisal and mefenamic acid. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
moderate Known Drug Interaction
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 ).
Dolobid
Ponstel
Diflunisal is a medicine that can help with pain and swelling. It belongs to a class of drugs called NSAIDs.
Mefenamic acid is a medicine used to treat mild to moderate pain and menstrual cramps. It is a type of nonsteroidal anti-inflammatory drug (NSAID).
Diflunisal can help with mild to moderate pain. It can also treat the symptoms of osteoarthritis and rheumatoid arthritis. You should use the lowest dose that works for you, for the shortest time needed.
Mefenamic acid is used to relieve mild to moderate pain in people 14 years and older. It should not be used for more than 7 days. It is also used to treat menstrual cramps.
Diflunisal reduces pain and swelling by blocking the production of certain chemicals in your body. These chemicals cause inflammation and pain. By blocking them, diflunisal helps to relieve your symptoms.
Mefenamic acid reduces pain and inflammation in the body. It does this by blocking substances in the body that cause pain and swelling. This medicine helps to reduce pain and discomfort.
- • Nausea
- • Vomiting
- • Upset stomach
- • Stomach pain
- • Diarrhea
- • Abdominal pain
- • Constipation
- • Diarrhea
- • Upset stomach
- • Gas
- Nausea 66
- Fatigue 57
- Pain 50
- Drug Hypersensitivity 47
- Headache 45
- Nausea 296
- Fatigue 253
- Headache 227
- Pain 202
- Dizziness 177
NSAIDs like diflunisal can increase your risk of heart problems like heart attack and stroke, which can be deadly. This risk is higher if you take it for a long time. You should not take diflunisal if you are having heart bypass surgery. NSAIDs also raise your risk of serious stomach problems like bleeding and ulcers, which can also be deadly. Older adults are at higher risk for these stomach problems.
Mefenamic acid may increase the risk of serious heart problems, including heart attack and stroke, which can be fatal. This risk may occur early in treatment and may increase with longer use. You should not take this medicine if you are having heart bypass surgery. Mefenamic acid can also increase the risk of serious stomach and intestinal problems, including bleeding, ulcers, and holes, which can be fatal. These problems can occur without warning. The elderly and those with a history of stomach ulcers or bleeding are at higher risk.
Tell your doctor if you are pregnant or plan to become pregnant. Taking diflunisal late in pregnancy may harm your baby. It is not known if diflunisal passes into breast milk, so talk to your doctor before breastfeeding.
Tell your doctor if you are pregnant or plan to become pregnant. Mefenamic acid may harm your unborn baby. It is not known if mefenamic acid passes into breast milk. Talk to your doctor before breastfeeding.
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How to Read This diflunisal vs mefenamic acid Comparison
diflunisal is classified in the Nonsteroidal Anti-Inflammatory Drug (NSAID) drug class, while mefenamic acid sits within the Nonsteroidal Anti-Inflammatory Drug (NSAID) class. Because both drugs share the same classification, they are often considered interchangeable in theory, but clinical outcomes rarely track that cleanly. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, diflunisal has 265 submissions while mefenamic acid has 1,155. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known moderate interaction flagged in FDA labeling, attributed to 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.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot represent individual circumstances. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This registry does not provide medical, treatment, substitution, or medication-change directions for diflunisal or mefenamic acid.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.