Mefenamic acid
Also sold as: Ponstan, Meftal
Prescription neededAnti-inflammatory painkillers (NSAIDs)
Comes as:CapsuleTabletSuspension
Usual adult dose
Usual adult dose: 500 mg three times a day after food. Mostly used for period pain; do not use for more than 7 days at a time.
Your doctor may give you a different dose. Children's doses depend on weight.
Side effects
Common
- stomach pain
- nausea
- diarrhoea
- drowsiness
Serious — get help
Stop taking it and see a doctor straight away if you notice:
- severe or bloody diarrhoea
- black stools
- vomiting blood
- severe allergic reaction
Do not take it, or take care, if
- Stomach ulcer or stomach bleeding, now or before
- Inflammatory bowel disease
- Severe kidney, liver or heart failure
- Asthma that gets worse with aspirin or similar painkillers
- Last 3 months of pregnancy
Interactions
Medicines that can react with this one.
Serious1 medicineDo not take these together unless your doctor says so.
- Warfarin
Raises the risk of serious bleeding.
Moderate1 medicineTake together only with care. Ask your doctor or pharmacist.
- Lithium carbonate
Can raise lithium levels in the blood; levels may need checking.