Know the basics
What is mefenamic acid used for?
Mefenamic acid is used for the short-term treatment of mild to moderate pain from various conditions. It is also used to decrease pain and blood loss from menstrual periods.
Mefenamic acid is known as a nonsteroidal anti-inflammatory drug (NSAID).
OTHER USES: This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.
How should I take mefenamic acid?
Take mefenamic acid by mouth, usually 4 times a day with a full glass of water (8 ounces or 240 millilitres) or as directed by your doctor. Do not lie down for at least 10 minutes after taking this drug. If stomach upset occurs, take mefenamic acid with food or milk. Do not take mefenamic acid with antacids unless directed by your doctor. Certain antacids may change the amount of mefenamic acid absorbed by the body.
Dosage is based on your medical condition and response to therapy. To reduce your risk of stomach bleeding and other side effects, take mefenamic acid at the lowest effective dose for the shortest possible time. Do not increase your dose, take it more frequently, or take it for a longer time than prescribed. Mefenamic acid usually should not be taken for more than 7 days at a time.
If you are taking this drug on an “as needed” basis (not on a regular schedule), remember that pain medications work best if they are used as the first signs of pain occur. If you wait until the symptoms have worsened, the medicine may not work as well.
If you are using mefenamic acid for painful periods, take your first dose as soon as your period starts or pain begins. Usually, you will only need to take it for the first 2 to 3 days of your period.
Inform your doctor if your pain persists or worsens or if you develop new symptoms.
How do I store mefenamic acid?
Mefenamic acid is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store mefenamic acid in the bathroom or the freezer. There may be different brands of mefenamic acid that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.
You should not flush mefenamic acid down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.
Know the precautions & warnings
What should I know before using mefenamic acid?
Before taking mefenamic acid,
- Tell your doctor and pharmacist if you are allergic to mefenamic acid, aspirin or other nsaids such as ibuprofen (Advil, Motrin) and naproxen (Aleve, Naprosyn), any other mefenamic acid s, or any of the inactive ingredients in mefenamic acid capsules. Ask your pharmacist for a list of the inactive ingredients.
- Tell your doctor and pharmacist what prescription and nonprescription mefenamic acid s, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention those medications: antacids; angiotensin-converting enzyme (ACE) inhibitors such as benazepril (Lotensin), captopril (Capoten), enalapril (Vasotec), fosinopril (Monopril), lisinopril (Prinivil, Zestril), moexipril (Univasc), perindopril (Aceon), quinapril (Accupril), ramipril (Altace), and trandolapril (Mavik); amiodarone (Cordarone, Pacerone); atazanavir (Reyataz); clopidogrel (Plavix); diuretics (‘water pills’), efavirenz (Sustiva); fluconazole (Diflucan); fluvastatin (Lescol); metronidazole (Flagyl); lithium (Eskalith, Lithobid); lovastatin (Mevacor); methotrexate (Rheumatrex); ritonavir (Norvir, in Kaletra); sulfamethoxazole (in Bactrim, in Septra); sulfinpyrazone (Anturane); trimethoprim (Proloprim); and zafirlukast (Accolate). Your doctor may need to change the doses of your medications or monitor you more carefully for side effects.
- Tell your doctor if you have or have ever had any of the conditions like: asthma, especially if you also have frequent stuffed or runny nose or nasal polyps (swelling of the inside of the nose); swelling of the hands, feet, ankles, or lower legs (fluid retention); or liver or kidney disease.
- Tell your doctor if you are pregnant, especially if you are in the last few months of your pregnancy, you plan to become pregnant, or you 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.
Is it safe to take mefenamic acid during pregnancy or breast-feeding?
There are no adequate studies in women for determining risk when using mefenamic acidduring pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking this mefenamic acid . Mefenamic acidis pregnancy risk category C according to the US Food and Drug Administration (FDA).
FDA pregnancy risk category reference below:
- A=No risk,
- B=No risk in some studies,
- C=There may be some risk,
- D=Positive evidence of risk,
Know the side effects
What are the side effects of mefenamic acid?
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop taking mefenamic acid and seek medical attention or call your doctor at once if you have any of these serious side effects:
- Chest pain, weakness, shortness of breath, slurred speech, problems with vision or balance;
- Black, bloody, or tarry stools, coughing up blood or vomit that looks like coffee grounds;
- Urinating less than usual or not at all;
- Pain, burning, or bleeding when you urinate;
- Nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
- Fever, sore throat, and headache with a severe blistering, peeling, and red skin rash; or
- Bruising, severe tingling, numbness, pain, muscle weakness.
Less serious side effects may include:
- Upset stomach, mild heartburn or stomach pain, diarrhea, constipation; bloating, gas;
- Dizziness, headache, nervousness;
- Skin itching or rash;
- Dry mouth;
- Increased sweating, runny nose;
- Blurred vision; or
- Ringing in your ears.
Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist
Know the interactions
What drugs may interact with mefenamic acid?
Mefenamic acidmay interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.
Tell your doctor if you are taking an antidepressant such as citalopram (Celexa), duloxetine (Cymbalta), escitalopram (Lexapro), fluoxetine (Prozac, Sarafem, Symbyax), fluvoxamine (Luvox), paroxetine (Paxil), sertraline (Zoloft), or venlafaxine (Effexor). Taking any of these drugs with mefenamic acid may cause you to bruise or bleed easily.
Before taking mefenamic acid, tell your doctor if you are taking any of the following drugs:
- A blood thinner such as warfarin (Coumadin;
- A diuretic (water pill) such as furosemide (Lasix);
- Cyclosporine (Gengraf, Neoral, Sandimmune);
- Lithium (Eskalith, Lithobid);
- Methotrexate (Rheumatrex, Trexall);
- Steroids (prednisone and others); or
- Aspirin or nsaids (non-steroidal anti-inflammatory drugs) such as diclofenac (Voltaren), etodolac (Lodine), fenoprofen (Nalfon), flurbiprofen (Ansaid), ibuprofen (Advil, Motrin), indomethacin (Indocin), ketoprofen (Orudis), ketorolac (Toradol), meclofenamate (Meclomen), meloxicam (Mobic), nabumetone (Relafen), naproxen (Aleve, Naprosyn), piroxicam (Feldene), and others.
Does food or alcohol interact with mefenamic acid?
Mefenamic acid may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.
What health conditions may interact with mefenamic acid?
Mefenamic acid may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have, especially:
- Bleeding problems;
- Blood clots;
- Edema (fluid retention or body swelling);
- Heart attack, history of;
- Heart disease (e.g., congestive heart failure);
- Hypertension (high blood pressure);
- Kidney disease;
- Liver disease (e.g., hepatitis);
- Stomach or intestinal ulcers or bleeding, history of;
- Stroke, history of—Use with caution. This medicine may make these conditions worse.
- Aspirin-sensitive asthma;
- Kidney disease, advanced;
- Stomach ulcers, active—This medicine should not be used in patients with these conditions.
- Heart surgery (e.g., coronary artery bypass graft [CABG] surgery)—This medicine should not be used to relieve pain right before or after the surgery.
Understand the dosage
The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this mefenamic acid .
What is the dose of mefenamic acid for an adult?
Usual Adult Dose for Pain
500 mg orally followed by 250 mg every 6 hours as needed, not to exceed 7 days
Usual Adult Dose for Dysmenorrhea
500 mg orally followed by 250 mg every 6 hours starting with the onset of menses
What is the dose of mefenamic acid for a child?
Usual Pediatric Dose for Pain
14 to 18 years: 500 mg orally followed by 250 mg every 6 hours as needed, not to exceed 7 days
How is mefenamic acid available?
Mefenamic acidis available in the following dosage forms and strengths:
- Capsule, Oral: 250 mg.
What should I do in case of an emergency or overdose?
In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.
What should I do if I miss a dose?
If you miss a dose of mefenamic acid , take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.
Hello Health Group does not provide medical advice, diagnosis or treatment.
Review Date: May 30, 2016 | Last Modified: December 19, 2019
Mefenamic Acid. https://www.drugs.com/mtm/mefenamic-acid.html. Accessed June, 30, 2016.
Mefenamic Acid. http://www.everydayhealth.com/drugs/mefenamic-acid. Accessed June, 30, 2016.
Mefenamic Acid. http://www.mayoclinic.org/drugs-supplements/mefenamic-acid-oral-route/description/drg-20070790. Accessed June, 30, 2016.