Alcohol
Contraindicated
Textbook-cited
Increased risk of gastric bleeding
Concurrent use is contraindicated
Source: KDT 7e · p950
Drug reference
Mefenamic acid
NSAID · Analgesic
NSAIDAnalgesic
CDSCO approvedSchedule H
EXCRETION
—
not curated
INTERACTIONS
12 major
incl. contraindicated
PREGNANCY
Avoid during third trimester (risk of premature closure of fetal ductus arteriosus and persistent pulmonary hypertension)
FDA category + note
Top interactionssee all 12 →
- AlcoholContraindicatedTextbook-citedKDT 7e · p950
- MethotrexateContraindicatedTextbook-citedKDT 7e · p949
- MethylprednisoloneContraindicatedTextbook-citedKDT 7e · p950
- CiprofloxacinSevereTextbook-citedKDT 7e · p949
Mechanism
Mefenamic acid is a fenamate (anthranilic acid derivative) NSAID that inhibits both cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), reducing prostaglandin synthesis. Unlike most NSAIDs, fenamates also antagonize certain prostaglandin receptors, providing dual inhibition of prostaglandin synthesis and action. Its use is primarily for short-term analgesia and dysmenorrhea, limited to 7 days due to increased risk of diarrhea and hemolytic anemia with prolonged use.
Indications
Painacute migraine (unlicensed indication)menstrual migraine (unlicensed indication)dysmenorrhoeamenorrhagiaShort-term treatment of pain in soft-tissue injuriesDysmenorrheaRheumatoid arthritisOsteoarthritisanalgesic in muscle, joint and soft tissue pain (where strong antiinflammatory action is not needed)rheumatoid and osteoarthritis (some cases)
Dosing
- Adult
- 500 mg TDS after food. Duration: use for shortest possible time.
- Pediatric
- 12-17 years: 500 mg TDS
- Renal adjustment
- Avoid in severe renal impairment
- Hepatic adjustment
- Avoid in severe hepatic impairment
- Geriatric
- Lowest effective dose for shortest duration
- Max dose
- 1500 mg/day
Pharmacokinetics
Onset
Peak plasma concentrations (Cp) 2–4 h
Half-life
2–4 h
Protein binding
>90%
Metabolism
CYP2C9 oxidation; glucuronidation of parent drug and metabolites
Contraindications
- Active GI bleeding/ulceration
- History of NSAID-related GI bleeding
- Inflammatory bowel disease
- Severe heart failure
- Post-CABG surgery
- Not recommended for use in children
- Not recommended for use in pregnant women
Side effects
Common
Diarrhoea (discontinue if severe)NauseaHeadacheRash (discontinue)15% elevated liver enzymesDiarrhea (relatively common, may be severe and associated with steatorrhea and inflammation of the bowel)diarrhoea (dose-related)epigastric distressskin rashesdizzinessCNS manifestations
Serious
- GI haemorrhage/ulceration
- Haemolytic anaemia
- Acute interstitial nephritis
- Stevens-Johnson syndrome
- Renal failure
- Autoimmune hemolytic anemia (potentially serious but rare)
- haemolytic anaemia (rare but serious complication)
Pregnancy & lactation
Pregnancy
Avoid during third trimester (risk of premature closure of fetal ductus arteriosus and persistent pulmonary hypertension)
Lactation
Excreted in breast milk.
Drug interactions
Methotrexate
Contraindicated
Textbook-cited
Severe methotrexate toxicity (pancytopenia, mucositis)
Avoid concurrent use
Source: KDT 7e · p949
Methylprednisolone
Contraindicated
Textbook-cited
Significantly increased GI bleeding risk
Concurrent use is contraindicated; if unavoidable, add PPI
Source: KDT 7e · p950
Ciprofloxacin
Severe
Textbook-cited
Enhanced CNS toxicity including seizures
Avoid concurrent use
Source: KDT 7e · p949
Dexamethasone
Severe
Textbook-cited
Significantly increased GI bleeding risk
Concurrent use is contraindicated; if unavoidable, add PPI
Source: KDT 7e · p950
Glibenclamide
Severe
Textbook-cited
Hypoglycemia
Avoid concurrent use; substitute with paracetamol if analgesic needed
Source: KDT 7e · p949
Gliclazide
Severe
Textbook-cited
Hypoglycemia
Avoid concurrent use; substitute with paracetamol if analgesic needed
Source: KDT 7e · p949
Glimepiride
Severe
Textbook-cited
Hypoglycemia
Avoid concurrent use; substitute with paracetamol if analgesic needed
Source: KDT 7e · p949
Glipizide
Severe
Textbook-cited
Hypoglycemia
Avoid concurrent use; substitute with paracetamol if analgesic needed
Source: KDT 7e · p949
Heparin
Severe
Textbook-cited
Increased bleeding risk
Avoid concurrent use
Source: KDT 7e · p949
Hydrocortisone
Severe
Textbook-cited
Significantly increased GI bleeding risk
Concurrent use is contraindicated; if unavoidable, add PPI
Source: KDT 7e · p950
Levofloxacin
Severe
Textbook-cited
Enhanced CNS toxicity, seizure risk
Avoid concurrent use
Source: KDT 7e · p949
Related guidelines
Other NSAID drugs
Ask House about Mefenamic acid
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e, Goodman & Gilman 14e, BNF·Verified: 2026-05-10 · House clinical team