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Mefenamic acid

Generic name: mefenamic acid (me fe NAM ik)
Brand name: Ponstel
Dosage forms: oral capsule (250 mg)
Drug class: Nonsteroidal anti-inflammatory drugs

Medically reviewed by Drugs.com on Mar 11, 2021. Written by Cerner Multum.

What is mefenamic acid?

Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that is used short-term (7 days or less) to treat mild to moderate pain in adults and children who are at least 14 years old. Mefenamic acid is also used to treat menstrual pain.

Mefenamic acid may also be used for purposes not listed in this medication guide.

Warnings

Mefenamic acid can increase your risk of fatal heart attack or stroke. Do not use mefenamic acid just before or after heart bypass surgery (coronary artery bypass graft, or CABG). Mefenamic acid may also cause stomach or intestinal bleeding, which can be fatal.

Before taking this medicine

Mefenamic acid can increase your risk of fatal heart attack or stroke, even if you don't have any risk factors. Do not use this medicine just before or after heart bypass surgery (coronary artery bypass graft, or CABG).

Mefenamic acid may also cause stomach or intestinal bleeding, which can be fatal. These conditions can occur without warning while you are using mefenamic acid, especially in older adults.

You should not use mefenamic acid if you are allergic to it, or if you have:

Tell your doctor if you have ever had:

If you are pregnant, you should not take mefenamic acid unless your doctor tells you to. Taking an NSAID during the last 20 weeks of pregnancy can cause serious heart or kidney problems in the unborn baby and possible complications with your pregnancy.

Tell your doctor if you are breastfeeding.

Mefenamic acid is not approved for use by anyone younger than 14 years old.

How should I take mefenamic acid?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the lowest dose that is effective in treating your condition.

Mefenamic acid should not be used for longer than 7 days. Follow your doctor's dosing instructions very carefully.

If you use mefenamic acid long-term, you may need frequent medical tests.

This medicine can affect the results of certain medical tests. Tell any doctor who treats you that you are using mefenamic acid.

Store at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking mefenamic acid?

Avoid drinking alcohol. It may increase your risk of stomach bleeding.

Ask a doctor or pharmacist before using other medicines for pain, fever, swelling, or cold/flu symptoms. They may contain ingredients similar to mefenamic acid (such as aspirin, ibuprofen, ketoprofen, or naproxen).

Mefenamic acid side effects

Get emergency medical help if you have signs of an allergic reaction (sneezing, runny or stuffy nose, hives, wheezing or trouble breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Get emergency medical help if you have signs of a heart attack or stroke: chest pain spreading to your jaw or shoulder, sudden numbness or weakness on one side of the body, slurred speech, feeling short of breath.

Stop using mefenamic acid and call your doctor at once if you have:

  • shortness of breath (even with mild exertion);

  • swelling or rapid weight gain;

  • nausea, diarrhea, flu-like symptoms (fever, swollen glands, muscle aches, severe weakness);

  • a skin rash, no matter how mild;

  • signs of stomach bleeding--bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds;

  • liver problems--loss of appetite, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

  • kidney problems--little or no urination, swelling in your feet or ankles, feeling tired or short of breath; o

  • low red blood cells (anemia)--pale skin, unusual tiredness, feeling light-headed or short of breath, cold hands and feet.

Common side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Mefenamic acid dosing information

Usual Adult Dose for Pain:

Initial dose: 500 mg orally once
Following initial dose: 250 mg orally every 6 hours as needed
Duration of therapy: Usually not to exceed 1 week

Use: For the relief of acute pain

Usual Adult Dose for Dysmenorrhea:

Initial dose: 500 mg orally once
Following initial dose: 250 mg orally every 6 hours as needed
Duration of therapy: 2 to 3 days

Comments:
-Treatment should begin at the onset of bleeding and associated symptoms.

Use: For the treatment of primary dysmenorrhea

Usual Pediatric Dose for Pain:

14 years or older:
-Initial dose: 500 mg orally once
-Following initial dose: 250 mg orally every 6 hours as needed
-Duration of therapy: Usually not to exceed 1 week

Use: For the relief of acute pain

Usual Pediatric Dose for Dysmenorrhea:

14 years or older:
-Initial dose: 500 mg orally once
-Following initial dose: 250 mg orally every 6 hours as needed
-Duration of therapy: 2 to 3 days

Comments:
-Treatment should begin at the onset of bleeding and associated symptoms.

Use: For the treatment of primary dysmenorrhea

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What other drugs will affect mefenamic acid?

Ask your doctor before using mefenamic acid if you take an antidepressant. Taking certain antidepressants with an NSAID may cause you to bruise or bleed easily.

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may affect mefenamic acid, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.