Mefenamic acid is a medication used to treat pain, including menstrual pain. It decreases inflammation (swelling) and uterine contractions.
This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.
How should this medicine be used?
Mefenamic acid comes as a capsule to take by mouth. It is taken every 6 hours as needed for up to 1 week. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take mefenamic acid exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Before taking mefenamic acid,
- tell your doctor and pharmacist if you are allergic to mefenamic acid, aspirin or other medications for pain or arthritis, or any other drugs.
- tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially anticoagulants ('blood thinners') such as warfarin (Coumadin), aspirin, atenolol (Tenormin), carteolol (Cartrol), cyclosporine (Neoral, Sandimmune), diuretics ('water pills'), labetalol (Normodyne, Trandate), lithium (Eskalith, Lithobid), medications for arthritis or diabetes, methotrexate, metoprolol (Lopressor), nadolol (Corgard), phenytoin (Dilantin), probenecid (Benemid), and vitamins.
- tell your doctor if you have or have ever had liver, heart, or kidney disease; high blood pressure; any stomach problems; or any other gastrointestinal disease.
- tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking mefenamic acid, call your doctor.
- if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking mefenamic acid.
- you should know that this drug may make you drowsy. Do not drive a car or operate machinery until you know how this drug affects you.
- remember that alcohol can add to the drowsiness caused by this drug. Do not drink alcohol while taking this medication.
What special dietary instructions should I follow?
Mefenamic acid may cause an upset stomach. Take mefenamic acid with food or milk.
What should I do if I forget a dose?
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
What side effects can this medication cause?
Although side effects from mefenamic acid are not common, they can occur. Tell your doctor if any of these symptoms are severe or do not go away:
- headache
- dizziness
- nervousness
- upset stomach
- stomach pain or cramps
- vomiting
- gas
If you experience any of the following symptoms, call your doctor immediately:
- diarrhea
- bloody vomit
- bloody or black, tarry stools
- ringing in the ears
- blurred vision
- swelling of the hands, feet, ankles, or lower legs
- skin rash
- itching
- sore throat
- fever
What storage conditions are needed for this medicine?
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.
In case of emergency/overdose
In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.
What other information should I know?
Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to mefenamic acid.
Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.
The original text of this document is taken from the public domain resource document "Mefenamic Acid", at http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a681028.html. See the copyright statement at http://www.nlm.nih.gov/medlineplus/copyright.html, which says "Government information at NLM Web sites is in the public domain. Public domain information may be freely distributed and copied, but it is requested that in any subsequent use the National Library of Medicine (NLM) be given appropriate acknowledgement."