Mefenamic acid is one of the groups of medicines called non-steroidal anti-inflammatory drugs. It is used to relieve many different kinds of pain or discomfort but primarily for relief of period pain. It can also be prescribed to women after childbirth.

It is a prescription medicine and is the active ingredient in the brand-name drug Ponstel. Generic drugs usually cost less although they contain the same ingredient. 

By blocking a naturally occurring chemical called cyclo-oxygenase enzymes, the body produces fewer chemicals called prostaglandins. Some of these prostaglandins are produced at sites of injury and can cause pain and inflammation. So by blocking these from producing, Mefenamic Acid helps relieve pain and inflammation.

For a more complete answer on ‘What is Mefenamic Acid?’ talk with your doctor or consult the patient information leaflet.

Periods vary from woman to woman but for some women, they can be an extremely uncomfortable and painful experience that last for a prolonged amount of time.

Taking Mefenamic acid to relieve this pain allows women to go about their daily life, whatever stage of their menstrual cycle they’re in.

Mefenamic Acid Side Effects

Before taking Mefenamic acid, you should always first consult your doctor. You should not take Mefenamic acid if any of the following apply to you:

Are taking aspirin or other non-steroidal anti-inflammatory drugs for pain relief e.g. naproxen, diclofenac
Are in the last three months of your pregnancy
Have severe heart failure
Have a history of allergy to aspirin, ibuprofen or NSAIDs,
Have a history of stomach bleeding or perforation which may be related to the use of NSAIDs (naproxen,      ibuprofen, diclofenac) or aspirin
Are allergic to mefenamic acid or any other ingredients of this medicine
Have a history of, or active disorders of the stomach or intestines such as ulcerative colitis, Crohn’s disease, gastrointestinal cancers or diverticulitis
Have severe liver or kidney failure
Have recently had coronary artery bypass graft surgery
Are taking anticoagulants such as warfarin to prevent blood clots.
 Your prescription of Mefenamic acid may also be affected by a number of other factors, so you should make your doctor aware if any of the following apply:

Are taking antidepressants called selective serotonin re-uptake inhibitors
Are taking any other anti-inflammatory medicines including steroids
Have epilepsy
Regularly take a painkiller for headaches over a prolonged period
Have diabetes
Suffer from kidney disease and dehydration
Have systemic lupus erythematosus (SLE)
Are an older person
Suffer from asthma or have had a history of asthma
Have ulcerative colitis or Crohn’s disease
Are known to be a poor metabolizer of CYP2C9
Suffer from liver disease
Have heart problems, previous stroke or think you might be at risk of these conditions
Have a bleeding disorder or if you are going to have a major operation
Are taking any other NSAIDs (e.g. ibuprofen, diclofenac)
Are taking aspirin or medicines that thin the blood
Have a problem with the metabolism of sugar in your body
Like many medications with active ingredients, Mefenamic acid can affect or be affected by other medicines. Particular medications that you may experience this with include the following:

Probenecid used in the treatment of gout
Zidovudine which is used in the treatment of AIDS and HIV infection
Anti-platelet agents (used to prevent blood clots)
Mifepristone
Cyclosporin
Antihypertensives and ACE inhibitors, used to treat high blood pressure
Certain medicines used to treat heart conditions known as cardiac glycosides
Low dose aspirin (75mg) to help prevent heart attack or stroke
Corticosteroids,
Certain medicines for depression such as lithium
Methotrexate
Quinolone antibiotics
Diuretics such as hydrochlorothiazide
Tacrolimus which is used to suppress the immune system
Aminoglycoside antibiotics
Some diabetic medicines such as (e.g. glipizide, glibenclamide).
If you are taking any of the above medications, then you should make your doctor aware so that they can advise whether or not Mefenamic acid will be the best course of action for you.

If you are pregnant then you should consult your doctor before taking Mefenamic acid. It is definitely not suitable for those in the last 3 months of pregnancy, but affects on the baby in the first 6 months are not known. This means it’s not usually recommended but your doctor may prescribe it you if they feel it necessary. However, you should not take Mefenamic acid if you are trying to get pregnant, as the drug will make it more difficult.

If you are breastfeeding then you should be aware that Mefenamic acid can be passed into your breast milk and should therefore not be taken during this time unless expressly instructed to do so by your doctor.

 The most common side effects of using Mefenamic acid include:

Oily stools
Stomach ache, indigestion, abdominal pain/discomfort
Feeling sick (nausea), vomiting, loss of appetite
Diarrhoea or constipation, wind
Sore mouth and/or lips
Blood in the stools or urine
Inflammation of the pancreas, stomach, small intestine or colon
If you do experience one or more of these side effects and they persist or worsen, then inform your doctor right away. You should also contact your doctor immediately if you experience any serious side effects, such as vomiting blood, severe skin reaction, or difficulty breathing.