Non-selective NSAID

Mefenamic acid

Brand names: Ponstan

A non-steroidal anti-inflammatory drug used for dysmenorrhoea, heavy menstrual bleeding, and mild to moderate pain.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It inhibits cyclo-oxygenase, reducing prostaglandin synthesis and thereby easing pain, inflammation and menstrual blood loss.

Prescribing in practice

As with other NSAIDs it carries gastrointestinal bleeding, cardiovascular and renal risks; use the lowest effective dose for the shortest time and consider gastroprotection in at-risk patients.
Overdose can provoke convulsions, so counsel against exceeding the recommended dose.
Avoid in active peptic ulceration, severe heart failure, significant renal impairment, and in the third trimester of pregnancy.

Monitoring

Monitor for gastrointestinal symptoms, blood pressure and renal function in those with risk factors or on prolonged treatment.

Counselling the patient

Take with or after food to reduce stomach upset.
Stop and seek advice if you have black stools, vomit blood, or develop severe indigestion.
It is most effective for period pain and heavy bleeding when started as symptoms begin.

Evidence & guidelines

NICE guidance on heavy menstrual bleeding (NG88) lists NSAIDs such as mefenamic acid among pharmacological options, particularly where dysmenorrhoea coexists.

Reference: NICE NG88; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Pathways