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What are the side effects of mefenamic acid?

There are many possible side effects of mefenamic acid. The most common, occurring in approximately 1% to 10% of people taking the drug, are:

  • abdominal pain
  • constipation
  • diarrhea
  • heartburn
  • nausea
  • vomiting
  • gas
  • abnormal kidney function
  • low red blood cell count (anemia)
  • dizziness
  • edema
  • abnormal liver tests
  • headaches
  • prolonged bleeding
  • itching
  • rashes
  • ringing in the ears
  • bleeding, ulcers and/or perforation of the stomach or intestines

Less common side effects are:

  • fever
  • infection
  • fluid retention
  • congestive heart failure
  • high blood pressure
  • increased heart rate
  • fainting
  • dry mouth
  • inflammation of the mouth, tongue or esophagus
  • hepatitis
  • jaundice
  • bruising
  • high blood eosinophil counts
  • low white blood cell counts
  • low platelet counts
  • bleeding from the rectum
  • dark tarry stools
  • weight changes
  • anxiety
  • confusion
  • depression
  • dream abnormalities
  • drowsiness
  • difficulty with sleeping
  • generalized feeling of being unwell
  • nervousness
  • numbness/tingling, tremors and a spinning sensation
  • wheezing
  • shortness of breath
  • hair loss
  • skin excessively sensitive to the sun
  • sweating
  • blurred vision
  • inflammation of the bladder or kidneys
  • painful urination
  • blood in urine
  • reduced or no urine production
  • protein in the urine
  • kidney failure

Rare side effects of mefenamic acid include:

  • severe allergic reactions
  • appetite changes
  • irregular heart rhythms
  • low blood pressure
  • heart attack
  • stroke
  • inflammation of blood vessels
  • liver failure
  • inflammation of the pancreas
  • swollen lymph nodes
  • low red blood cell counts due to destruction of red blood cells
  • aplastic anemia or pancytopenia (with decreased numbers of all blood cells: white, red and platelets)
  • increased blood glucose
  • seizures
  • coma
  • hallucinations
  • meningitis
  • slowing of breathing
  • pneumonia
  • severe skin disorders
  • inflammation of the eye
  • decreased hearing
  • death

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.