Mefenamic Acid Side Effects, Overdose and Pregnancy Information

Mefenamic Acid side effects include, abdominal pain, diarrhea, constipation, dizziness, fluid retention and swelling, heartburn, indigestion, nausea, nervousness, rash, and vomiting. Rare Mefenamic Acid side effects may include, abdominal bleeding, blood in urine, blurred vision, changes in heartbeat, confusion, depression, dry eyes, hives, inability to sleep, kidney or liver damage, severe allergic reactions, shortness of breath, sleepiness, stomach ulcer, vomiting blood, painful urination. Ulcers or internal bleeding can happen especially when Mefenamic Acid is used for long time or in large doses.

Mefenamic Acid Side Effects Reporting

If you experience any Mefenamic Acid side effects not mentioned above you should report it to your primary health care provider or FDA 1-800-FDA-1088 in the United States, Health Canada 1-866-225-0709 in Canada, MHRA 020 3080 6000 in UK, or TGA 1800 020 653 in Australia.


Mefenamic Acid is a Non-steroidal anti-inflammatory drug (NSAIDs). Mefenamic Acid is used for to relieve the pain and inflammation of the rheumatoid arthritis and osteoarthritis, treatment of menstrual pain, and relief of mild to moderate pain, migraine and to reduce fever. Mefenamic Acid works by blocking and reducing the level of Prostaglandins. Prostaglandins is a chemical produced in the body in response to injury and certain diseases and conditions and is responsible for causing inflammation, pain and fever. Relief from pain and fever usually comes within an hour of taking Mefenamic Acid; however, anti-inflammatory effects could take days or even weeks to become apparent. Mefenamic Acid is available over-the-counter and with prescription.

Mefenamic Acid Overdose

Mefenamic Acid overdose symptoms may include acute depression, abdominal pain, short breath, drowsiness, irregular heartbeat, kidney failure, low blood pressure, nausea, seizures, and vomiting and even death. In case of an Mefenamic Acid overdose, seek medical attention right away. If you miss a dose of Mefenamic Acid, take it as soon as you can. However, if it is just about time for your next dose, skip the one you forgot and go on with your regular schedule. Never take a double dose of Mefenamic Acid.

Mefenamic Acid Caution

Avoid taking Mefenamic Acid if you are sensitive or allergic to aspirin, or if you have asthma.

Inform your physician any drug reactions that you have experienced with Mefenamic Acid in the past.

Drinking alcohol increases the side effects of Mefenamic Acid especially bleeding.

Do not use more than the dosage prescribed by your physician.

Taking Mefenamic Acid with blood pressure medicines such as beta-blockers and diuretics lowers their effectiveness.

Peptic ulcers and bleeding can occur without warning when using Mefenamic Acid.

Mefenamic Acid should be used with caution if you have kidney or liver disease.

Do not take aspirin or any other anti-inflammatory drugs while taking Mefenamic Acid unless advised by your physician.

If you have a severe allergic reaction from Mefenamic Acid, seek medical help right away.

If you are taking blood-thinning medication such as warfarin, Mefenamic Acid may extend bleeding time.

Mefenamic Acid should be taken with food to avoid stomach irritation.

The smallest effective dose of Mefenamic Acid should be used for the shortest time possible to relieve the symptoms. If symptoms persist despite treatment, seek medical advice from your physician or pharmacist.

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) such as Mefenamic Acid may be linked with a small increase in the risk of a heart attack or stroke. The risk is associated with high doses and prolonged use of Mefenamic Acid.

Mefenamic Acid should be used with caution in seniors, people with history of disorders of stomach or intestines such as Crohn's disease or colitis decreased kidney or liver functions, heart failure, high blood pressure (hypertension), angina or history of heart attack, disease of the blood vessels in and around the brain, history of stroke or mini stroke, poor circulation, diabetes, blood clotting disorders, and asthma.

Mefenamic Acid and Pregnancy

Mefenamic Acid may affect the heart of the developing fetus. If you are pregnant especially the last half of the pregnancy or might become pregnant, you should consult your physician or gynecologist before taking Mefenamic Acid. Mefenamic Acid may pass into breast milk that could affect the heart of the baby. Nursing mothers should bottle feed while taking Mefenamic Acid.

Mefenamic Acid Doses

ADULTS AND CHILDREN 14 AND OLDER: The standard start dose is 500mg then 250mg every 6 hours in divided dosage.

CHILDREN UNDER 14: Not recommended.

Mefenamic Acid Interactions

Always inform your doctor or pharmacist if you are taking any other prescription or over-the-counter (OTC) drugs, including vitamins and herbs.

Mefenamic Acid should not be taken in combination with other painkillers such as Aspirin or ibuprofen, as this increases the risk of side effects on the stomach and intestines. Other COX-2 inhibitors should also be avoided for the same reason.

There may be an increased risk of ulceration or bleeding in the stomach if Mefenamic Acid is taken with corticosteroids or with the following drugs:

Anti-blood-clotting (anticoagulant) drugs
Anti-platelet drugs
SSRI antidepressants
Check with your physician before combining Mefenamic Acid with the following:

Blood pressure drugs such as ACE inhibitors and beta-blockers
Blood thinners
Lithium
Diuretics
Methotrexate

Do not combine Mefenamic Acid with herbs like Garlic, Ginkgo and Ginseng.
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