NSAIDPainkiller
Mefenamic Acid
Tablet or capsule
Quick Summary
Mefenamic acid is an NSAID that reduces the chemicals that cause period cramps and heavy bleeding.
Period pain
Heavy periods
Mild to moderate pain
Medical Uses
Period pain: Taken at the start of pain or bleeding.
Heavy periods: Can reduce blood loss.
Mild to moderate pain: Short-term.
How it's taken
Take it with or after food, only for a few days at a time.
Your doctor decides the right dose for you and how long to take it.
Your doctor decides the right dose for you. Follow their instructions and the label.
Common Side Effects
Diarrhoea
Stop and see a doctor if severe.
Stomach upset
Nausea or pain.
Drowsiness
Or dizziness.
Interactions
Blood thinners
Increase bleeding risk.
Other NSAIDs
Avoid combining.
Critical Warnings
Stomach and kidney problems
Not suitable for everyone; ask your doctor.
Severe diarrhoea or rash
Stop and seek advice.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Mefenamic Acid: drug information(opens in a new tab) · MedlinePlus, US National Library of Medicine