Guide to Mefenamic Acid Usage

Mefenamic acid is a common medication used to treat various types of pain. It belongs to a group of drugs called non-steroidal anti-inflammatory drugs (NSAIDs), which is typically taken by mouth. It works by reducing your body's production of an inflammatory substance that causes fever, swelling and pain.

Precautions Before Taking Mefenamic Acid

Although mefenamic acid is a medication that may be bought over-the-counter, there are some things to keep in mind before taking it, including:

Take Mefenamic Acid Safely

Take mefenamic acid as directed by your doctor or as written on the medication’s label. You should check with your doctor or pharmacist if you are not sure. The following are some important things you should keep in mind when taking mefenamic acid:

Possible Side Effects and Interactions with Mefenamic Acid

Mefenamic is effective in treating pain and inflammation, but like other medications, it may have some side effects. It may also interact with other medications or medical conditions, so it’s advisable to tell your doctor if you are taking other medications. Let’s take a look at the side effects and interactions when taking mefenamic acid.

Side Effects


  • Chest pain, shortness of breath, weakness, slurred speech, vision/balanceproblems
  • Coughing up blood, bloody, black/tarry stools, coffee ground appearance of vomit
  • Decreased urination
  • Painful or bloody urine
  • Loss of appetite, stomach pain, nausea, low fever, clay-colored stools, dark urine, yellowing of the skin/eyes
  • Sore throat, fever and headache with skin rash
  • Bruising, numbness, severe tingling, muscle weakness,  pain
  • Upset stomach, stomach pain, constipation/diarrhea, bloating, gas
  • Headache, dizziness, nervousness
  • Rash, skin itching
  • Dry mouth
  • Runny nose, increased sweating
  • Ringing in the ears
  • Blurred vision
  • Very serious interactions with cidofovir and ketorolac
  • Medications containing pain relievers or fever reducers such as aspirin and NSAIDs such as ibuprofen and celecoxib
  • An increased risk of bleeding when taken with anti-platelet drugs (ex. Clopidogrel) and "blood thinners" (ex. enoxaparin, Dabigatran, warfarin)
  • Let your doctor know the following medications that you are taking before using mefenamic acid: nonprescription or herbal products such as aliskiren, angiotensin II receptor blockers (ex. valsartan, losartan), ACE inhibitors (ex.  captopril, lisinopril), "water pills" (diuretics such as furosemide), cyclosporine, desmopressin, corticosteroids (ex.  prednisone), fluconazole, lithium, pemetrexed, probenecid, methotrexate, tenofovir 

What to Do in Case of an Emergency

When Experiencing Serious Symptoms

Stop using mefenamic acid and immediately contact your doctor IF:

When Overdosing

Call your local poison control center immediately. If a victim has collapsed or is not breathing, call 911 right away.

As mentioned above, mefenamic acid overdose symptoms include:

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