About mefenamic acid

Mefenamic acid belongs to a group of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). Other NSAIDs include ibuprofen, indometacin, naproxen, and diclofenac. There are several others as well.

It is used to relieve mild to moderate pain after operations and in rheumatoid arthritis and osteoarthritis. Mefenamic acid can also be used to treat period pain associated with heavy menstrual bleeding in women.

A substance in the body called cyclo-oxygenase is involved in the production of various chemicals in the body, including prostaglandins. Prostaglandins are produced in response to injury and certain diseases and conditions, and cause pain, swelling and inflammation.

Mefenamic acid works by blocking the action of cyclo-oxygenase and so stops the production of these irritant chemicals. This results in less pain, swelling and inflammation.

Before taking mefenamic acid

Before taking mefenamic acid make sure your doctor or pharmacist knows:

• If you are pregnant, trying for a baby or breast-feeding.
• If you have ever had a stomach or duodenal ulcer.
• If you suffer from liver or kidney problems.
• If you suffer from asthma or any other allergic disorder.
• If you suffer from a blood disorder or blood clotting problems.
• If you have an inflammatory bowel disease such as Crohn's disease or ulcerative colitis.
• If you have a heart condition.
• If you have epilepsy.
• If you suffer from porphyria (a rare blood disorder).
• If you have ever had an allergic or unusual reaction to any other NSAID (this includes aspirin, ibuprofen, naproxen, diclofenac and indometacin) or to any other medicine.
• If you are under 12 years of age or elderly.
• If you are taking other medicines, including those available to buy without a prescription, herbal or complementary medicines.

How to take mefenamic acid

• Before beginning treatment, read the manufacturer's printed information leaflet.
• Take mefenamic acid exactly as your doctor has told you.
• Take your dose with a meal or just after eating some food.
• Try to take mefenamic acid at the same times each day to avoid missing any doses.
• If you do forget to take a dose, take one as soon as you remember unless it is nearly time for your next dose in which case skip the missed dose. Do not take two doses at the same time to make up for a missed dose.

Getting the most from your treatment

• Keep your regular doctor's appointment so your progress can be monitored.
• If you buy any medicines, check with a pharmacist that they are safe to take with mefenamic acid.
• Mefenamic acid may cause your skin to become more sensitive to sunlight than usual. Do not use sunbeds, and avoid direct sunlight or use a sun cream with a sun protection factor of 15 or higher until you know how your skin reacts.

Can mefenamic acid cause problems?

Along with their useful effects, all medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Important: if you experience any of the following, speak with your doctor or go to your local accident and emergency department without delay:

• Any sign of bleeding in the stomach or intestine, such as blood in vomit or dark stools.
• Any shortness of breath or swelling of the mouth or face.
• A skin rash.

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

How to store mefenamic acid

• Keep all medicines out of the reach and sight of children.
• Store in a cool, dry place, away from direct heat and light.

Important information about all medicines