Mefenamic acid

Overview

NSAID used for heavy menstrual bleeding and primary dysmenorrhoea — particularly useful when both heavy AND painful periods (cross-references the general NSAID class).

Mechanism

Inhibits cyclo-oxygenase → reduces endometrial prostaglandin synthesis → less menstrual blood loss and less uterine cramping. Taken during menstruation only.

Indications

• Heavy menstrual bleeding (esp. with dysmenorrhoea)
• Primary dysmenorrhoea

Adverse effects

Cautions & contraindications

Interactions

• ACEi + diuretic → "triple whammy" AKI
• ↑bleeding risk with anticoagulants

Monitoring & kinetics

Renal function if risk factors

Oral, during menses. For HMB: LNG-IUS is first-line; tranexamic acid (less pain effect) or mefenamic acid are alternatives.