Generic Name: mefenamic acid (mef-e-NAM-ik AS-id)
NSAIDs cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. This risk may occur early in treatment and may increase with duration of use. Mefenamic acid is contraindicated in the setting of CABG surgery. NSAIDs can also cause an increased risk of serious gastrointestinal (GI) adverse events including bleeding, ulceration, and perforation of the stomach or intestines, which can be fatal. These events can occur at any time during use and without warning symptoms. Elderly patients and patients with a prior history of peptic ulcer disease or GI bleeding are at greater risk for serious GI events .
Medically reviewed by Drugs.com. Last updated on Aug 19, 2020.
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Analgesic
Pharmacologic Class: NSAID
Chemical Class: Fenamate
Uses for mefenamic acid
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used to treat mild to moderate pain. It may also be used to treat menstrual cramps and other conditions as determined by your doctor.
Mefenamic acid is available only with your doctor's prescription.
Before using mefenamic acid
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For mefenamic acid, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to mefenamic acid or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of mefenamic acid in children below 14 years of age. Safety and efficacy have not been established.
Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of mefenamic acid in the elderly. However, elderly patients are more likely to have age-related kidney problems, which may require caution and an adjustment in the dose for patients receiving mefenamic acid.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking mefenamic acid, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using mefenamic acid with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using mefenamic acid with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Aluminum Carbonate, Basic
- Aluminum Hydroxide
- Aluminum Phosphate
- Amtolmetin Guacil
- Bismuth Subsalicylate
- Calcium Carbonate
- Choline Magnesium Trisalicylate
- Choline Salicylate
- Dabigatran Etexilate
- Dihydroxyaluminum Aminoacetate
- Dihydroxyaluminum Sodium Carbonate
- Ethacrynic Acid
- Flufenamic Acid
- Magnesium Carbonate
- Magnesium Hydroxide
- Magnesium Oxide
- Magnesium Salicylate
- Magnesium Trisilicate
- Niflumic Acid
- Nimesulide Beta Cyclodextrin
- Pentosan Polysulfate Sodium
- Phenyl Salicylate
- Protein C
- Salicylic Acid
- Sodium Bicarbonate
- Sodium Salicylate
- Tenofovir Disoproxil Fumarate
- Tiaprofenic Acid
- Tolfenamic Acid
- Trolamine Salicylate
Using mefenamic acid with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Azilsartan Medoxomil
- Candesartan Cilexetil
- Olmesartan Medoxomil
- Perindopril Erbumine
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other medical problems
The presence of other medical problems may affect the use of mefenamic acid. Make sure you tell your doctor if you have any other medical problems, especially:
- Anemia or
- Asthma or
- Bleeding problems or
- Blood clots or
- Congestive heart failure or
- Dehydration or
- Edema (fluid retention or body swelling) or
- Heart attack, history of or
- Hyperkalemia (high potassium in the blood) or
- Hypertension (high blood pressure) or
- Kidney disease or
- Liver disease (eg, hepatitis) or
- Stomach or intestinal ulcers or bleeding, history of or
- Stroke, history of—Use with caution. May make these conditions worse.
- Aspirin-sensitive asthma or
- Kidney disease, severe or
- Stomach ulcers, active—Should not be used in patients with these conditions.
- Heart surgery (including coronary artery bypass graft [CABG] surgery)—Should not be used for pain right before or after surgery.
Proper use of mefenamic acid
Take mefenamic acid only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. To do so may increase the chance for side effects.
Mefenamic acid should come with a Medication Guide. Read and follow these instructions carefully. Ask your doctor or pharmacist if you have any questions.
If mefenamic acid upsets your stomach, take it with food or milk.
The dose of mefenamic acid will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of mefenamic acid. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (capsules):
- For menstrual cramps:
- Adults and children 14 years of age and older—At first, 500 milligrams (mg), then 250 mg every 6 hours as needed, for 2 to 3 days.
- Children younger than 14 years of age—Use and dose must be determined by your doctor.
- For mild to moderate pain:
- Adults and children 14 years of age and older—At first, 500 milligrams (mg), then 250 mg every 6 hours as needed, for not more than 1 week.
- Children younger than 14 years of age—Use and dose must be determined by your doctor.
- For menstrual cramps:
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 go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions while using mefenamic acid
It is very important that your doctor check your progress at regular visits. to make sure mefenamic acid is working properly. Blood and urine tests may be needed to check for unwanted effects.
Mefenamic acid may raise your risk of having a heart attack or stroke. This is more likely in people who already have heart disease. People who use mefenamic acid for a long time might also have a higher risk. Check with your doctor right away if you are having chest pain or discomfort, nausea or vomiting, pain or discomfort in the arms, jaw, back, or neck, shortness of breath, slurred speech, or weakness.
Mefenamic acid may cause bleeding in your stomach or intestines. These problems can happen without warning signs. This is more likely if you have had a stomach ulcer in the past, if you smoke or drink alcohol regularly, are over 60 years of age, are in poor health, or using certain other medicines (such as a steroid or a blood thinner).
Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.
Serious skin reactions can occur with mefenamic acid. Check with your doctor right away if you have blistering, peeling, or loosening skin, red skin lesions, a severe skin rash or acne, sores or ulcers on the skin, or fever or chills while you are using mefenamic acid.
Possible warning signs of some serious side effects that can occur during treatment with mefenamic acid may include swelling of the face, fingers, feet, or lower legs, severe stomach pain, black, tarry stools, or vomiting of blood or material that looks like coffee grounds, unusual weight gain, yellow skin or eyes, decreased urination, bleeding or bruising, or skin rash. Also, signs of serious heart problems could occur such as chest pain, tightness in chest, fast or irregular heartbeat, unusual flushing or warmth of skin, weakness, or slurring of speech. Check with your doctor immediately if you notice any of these warning signs.
Mefenamic acid may cause a serious allergic reaction, called anaphylaxis. This can be life-threatening and requires immediate medical attention. Tell your doctor right away if you have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth after using mefenamic acid.
Using mefenamic acid during the later part of a pregnancy can harm your unborn baby. If you think you have become pregnant while using mefenamic acid, tell your doctor right away.
Tell your doctor if you have unexplained weight gain or edema (fluid retention or body swelling) while using mefenamic acid.
Make sure any doctor or dentist who treats you knows that you are using mefenamic acid. Mefenamic acid may affect the results of certain medical tests.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.
Mefenamic acid side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
- Bloody urine
- bloody, black, or tarry stools
- decreased frequency or amount of urine
- increased bleeding time
- increased blood pressure
- increased thirst
- itching skin
- loss of appetite
- lower back or side pain
- pale skin
- severe abdominal pain, cramping, or burning
- stomach bloating
- swelling of the face, fingers, feet, or lower legs
- trouble breathing with or without exertion
- unusual bleeding or bruising
- unusual tiredness or weakness
- vomiting of material that looks like coffee grounds, severe and continuing
- weight gain
- weight loss
- Bleeding gums
- blood in vomit
- blurred vision
- burning feeling in the chest or stomach
- chest pain
- clay-colored stools
- cloudy urine
- cough or hoarseness
- dark urine
- difficult or labored breathing
- difficult, burning, or painful urination
- difficulty in swallowing
- dilated neck veins
- extreme fatigue
- fast, pounding, or irregular heartbeat or pulse
- fever or chills
- frequent urge to urinate
- increased volume of pale, dilute urine
- irregular breathing
- irregular heartbeat
- large, flat, blue, or purplish patches in the skin
- light-colored stools
- noisy breathing
- pain or burning feeling in the throat
- pinpoint red or purple spots on the skin
- pounding in the ears
- rapid, slow breathing
- redness, swelling, or soreness of the tongue
- severe or continuing stomach pain
- slow heartbeat
- sore throat
- sores, ulcers, or white spots on the lips or tongue or inside the mouth
- stomach upset
- swelling or inflammation of the mouth
- swollen glands
- tenderness in the stomach area
- tightness in the chest
- unpleasant breath odor
- upper right stomach pain
- yellow eyes and skin
- Blistering, peeling, or loosening of the skin
- change in consciousness
- chest discomfort
- continuing vomiting
- cracks in the skin
- dizziness, faintness, or lightheadedness when suddenly getting up from a lying or sitting position
- fever with or without chills
- flushed, dry skin
- fruit-like breath odor
- general body swelling
- general feeling of illness
- high fever
- increased hunger
- irregular, fast or slow, or shallow breathing
- joint or muscle pain
- large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
- leg pain
- loss of consciousness
- loss of heat from the body
- no blood pressure
- no breathing
- no pulse
- painful glands
- pain or discomfort in the arms, jaw, back, or neck
- pains in the stomach, side, or abdomen, possibly radiating to the back
- pale or blue lips, fingernails, or skin
- puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
- racing heartbeat or pulse
- red skin lesions, often with a purple center
- red, irritated eyes
- red, swollen skin
- redness or soreness of the skin
- scaly skin
- seeing, hearing, or feeling things that are not there
- severe headache
- sores, welting, or blisters
- stiff neck or back
- swollen, painful, or tender lymph glands in the neck, armpit, or groin
- unexplained weight loss
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
- Unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- Continuing ringing or buzzing or other unexplained noise in the ears
- excess air or gas in the stomach or intestines
- feeling of fullness
- hearing loss
- passing gas
- stomach discomfort
- Burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
- dry mouth
- feeling of constant movement of self or surroundings
- feeling sad or empty
- hair loss, thinning of the hair
- increased sensitivity of the skin to sunlight
- lack of appetite
- lack of interest or pleasure
- lack or loss of strength
- redness or other discoloration of the skin
- sensation of spinning
- severe sunburn
- trouble concentrating
- trouble sleeping
- Appetite changes
- burning, dry, or itching eyes
- change in hearing
- discharge, excessive tearing
- redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
More about mefenamic acid
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Images
- Drug Interactions
- Pricing & Coupons
- En Español
- 64 Reviews
- Drug class: Nonsteroidal anti-inflammatory drugs
- FDA Alerts (4)
Other brands: Ponstel