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Non-selective NSAID

Mefenamic acid

Brand names: Ponstan

Adult dose

Dose: 500mg TDS for menorrhagia/dysmenorrhoea (start at onset of period for 3–5 days)

Route: PO

Frequency: TDS

Clinical pearls

Heavy menstrual bleeding (reduces blood loss ~25%) and dysmenorrhoea
High convulsion risk in overdose

Contraindications

Active GI bleeding/peptic ulcer
Severe renal/hepatic impairment
Severe heart failure
Aspirin/NSAID hypersensitivity
3rd trimester pregnancy

Side effects

GI upset/bleeding
Renal impairment
Diarrhoea
Haemolytic anaemia
Convulsions in overdose

Interactions

Anticoagulants
ACEi/ARB
Lithium
Methotrexate

Reference: BNF; NICE NG88; https://bnf.nice.org.uk/drugs/mefenamic-acid/. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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