• MEFAREX-500
  • Dosage Form: Tablets
  • Pack Type: Blister
  • Pack Size: 1X10's Tablets
  • Division: Unimax


Mefenamic Acid 500 mg

MEFAREX 500: Each uncoated tablet contains Mefenamic acid 500mg.

Clinical Pharmacology:

Mefenamic acid, an anthranilic acid derivative/fenamate is a NSAID (nonsteroidal antiinflammatory drug) with anlagesic, antipyretic and anti-inflammatory properties.It reversibly inhibits both isoforms of the enzyme cyclooxygenase ( COX-1 and COX-2), thus resulting in reduced synthesis of prostaglandins.

Mefenamic acid is used to treat mild to moderate pain for no more than a week.

It is generally prescribed for menstrual pain (primary dysmenrrhoea). It is also indicated to treat pain and inflammation in rheumatoid arthritis and osteoarthritis, postoperative pain, acute pain including muscle pain, back pain, headache and toothache. It is also prescribed for menorrhagia i.e. heavy menstrual bleeding.

Take Mefarex only as directed by your doctor. You will be prescribed the lowest effective dose over the shortest duration to reduce side effects. You should not take Mefarex for longer than 7 days as it may increase the chance for side effects.

The number of dosage you take each day, the time interval between the doses and the duration of the treatment all depends on the medical condition for which you are using the medicine, therefore, consult with your doctor or pharmacist for better understanding of the dosage regimen.

Usually, the recommended dose of Mefarex in adults is 1 tablet (500mg) three time a day. In dysmenorrhea, Mefarex is to be adminstered at the onset of menstrual pain and continued according to the judgement of the physician. In Menorrhagia, Mefarex is to be administered on the first day if excessive bleeding and continued according to the judgement of the physician.


The elderly are at increased risk of the serious consequences of adverse reactions. If Mefarex is considered necessary, the lowest effective dose should be used and for the shortest possible duration. 

Pediatric population

This formulation is not intended for use in children. 

Method of administration

Mefarex should be taken preferably with or after food. Tke Mefarex with a full glass of water unless your doctor directs you otherwise. If stomach upset occurs while taking Mefarex, take it with food or milk.


Tell your doctor or pharmacist if you are taking or have recently taken or might take any other medicines, including medicines obtained without a prescription, and herbal preparations. Some medicines may be affected by Mefenamic acid or they may affect how  Mefenamic acid  work.

- Concommitant use of two ar more NSAIDs may increase the risk of adverse effects.

- Concommitant use of mefenamic acid with following medicines can increase the chance of getting ulcers or a bleed in the stomach or gut:


• anti-platelet agents (e.g. warfarin, aspirin, clopidogrel)

• antidepressants called selective serotonin reuptake inhibitors (SSRIs) (e.g. paroxetine)

• any other anti-inflammatory medicines (e.g. diclofenac, celecoxib)

-Mefenamic acid can decrease renal lithium clearance and elevate plasma lithium levels. Patients should be observed carefully for signs of lithium toxicity.

-A reduction in antihypertensive and diuretic effect of antihypertensives and diuretics have been observed with mefenamic acid.

- Mefenamic acid may increase plasma cardiac glygoside levels.

- The risk of nephrotoxicity of ciclosporin / tacrolimus may be increased with mefenamic acid.

- Mefenamic acid may inhibit the  metabolism of sulfonylurea drugs and prolong its half-life thereby increasing the risk of hypoglycaemia.

-Elimination of Methotrexate is reduced by Mefenamic acid resulting in its increased plasma levels.

-Mefenamic acid should not be taken for 8-12 days after mifepristone administration, as it can reduce the effects of mifepristone.

-Probenecid reduces the metabolism and elimination of mefenamic acid.

-Patients taking mefenamic acid and quinolones may have an increased risk of developing convulsions.



STOP taking the tablets and seek medical help immediately;

-if you have any of the following allergic reactions:

  •  difficulty breathing or swallowing, swelling of the face, lips, tongue or throat
  •  severe itching of the skin, with a red rash or raised lumps
  •  blistering of the mouth, eyes, and genital region, and patchy areas of rash
  •  peeling skin   


-if you have any of the following reactions

  •   diarrhoea
  •   passing blood in your stools (faeces/motions)
  •   passing black tarry stools
  •   vomiting any blood or dark particles that look like coffee grounds

Seek immediate medical attention if you have any of the following symptoms:

  •   indigestion or heartburn, abdominal pain (pain in your stomach) or other abnormal stomach symptoms, nausea (feeling sick), vomiting
  •   any unusual bruising or bleeding, for example nose-bleeds, pinpoint red spots on the skin, unusual purple bruise-like rash on the skin or in the mouth
  •   signs of anaemia such as feeling tired, breathless, and looking pale
  •   fever, sore throat, mouth ulcers, repeated infections or infections that will not go away. This may be due to a low level of white blood cells
  •   seizures (fits)
  •   signs of low sodium levels such as headache, nausea, vomiting, tiredness, muscle cramps
  •   sudden headache, stiff neck, fever, sensitivity to bright light, drowsiness and muscle pain, with or without a rash
  •   fever, rash, nausea, aches and pains, passing more or less urine than usual, passing red urine or passing urine at night. This may be due to changes in your    kidneys
  •   sudden loss or blurring of vision, loss of colour vision, eye pain which worsens with eye movement
  •   headache, in particular on waking in the morning. This may be due to high blood pressure.
  •   pain behind the ribs radiating towards the back, often worse when lying down, nausea, vomiting, fever. This may be due to inflammation of your pancreas.
  •   yellowing of your skin or eyes, pale faeces and dark urine, unexplained persistent nausea, stomach problems, loss of appetite or unusual tiredness. This may be due to changes in your liver.


Do not take Mefenamic acid Tablets if you: -

  • are allergic to Mefenamic acid, or any of the other ingredients of this medicine or any other NSAIDs e.g. ibuprofen, aspirin
  • have, or have ever had, stomach or intestinal conditions such as peptic ulcer, bleeding in the stomach or severe gastritis 
  • have an inflammatory bowel disease (e.g. ulcerative colitis, Crohn’s disease)
  • have severe heart, liver or kidney problems
  • have just had heart bypass surgery
  • are more than 6 months pregnant

Warnings and precautions

Talk to your doctor before taking this medicine, if you:

  • have kidney or liver problems
  • are trying to become pregnant
  • have stomach or digestive tract problems or if you have ever had an upset stomach after taking pain killers such as aspirin 
  • have a bleeding disorder or if you are going to have a major operation
  • have asthma, or a history of asthma, as this medicine may cause breathing difficulties
  • have a connective tissue disorder, e.g. Systemic Lupus Erythematosus (SLE)
  • have epilepsy
  • have heart problems, previous stroke or think that you might be at risk of these conditions

Pregnancy, breast-feeding and fertility

Mefenamic acid is contraindicated in the last trimester of pregnancy due to its adverse effects on the fetal cardiovascular system (risk of closure of ductus arteriosus).Do not take mefenamic acid in the last 3 months of pregnancy as they may also delay the onset of labour and prolong its duration. They may also increase the likelihood of bleeding in the mother and in the baby. If you need to take these tablets, your doctor can help you decide whether or not to take them during the first 6 months of pregnancy.

Mefenamic acid passes into breast milk and can affect the baby. You should not take the tablets while breast-feeding unless advised by your doctor.

Do not  take these tablets if you are trying to become pregnant, as they may make it more difficult to get pregnant. If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor for advice before taking this medicine.