Patient Medication Information: uses, side effects, how to take - Mefenamic Acid
Serious warnings and precautions box
Heart and blood vessel problems:
Stomach and intestine (gastrointestinal) problems:
Pregnancy:
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What MEFENAMIC ACID is used for:
MEFENAMIC ACID is used in adults to treat:
- discomfort caused by muscular aches
- headache
- period cramps (primary dysmenorrhea)
- dental pain
How MEFENAMIC ACID works:
MEFENAMIC ACID belongs to a group of medicines called nonsteroidal anti-inflammatory drugs (NSAIDs). It works by reducing the chemicals produced by your body which cause pain and swelling.
MEFENAMIC ACID only relieves pain and reduces swelling as long as you continue to take it. It does NOT cure your illness or stop it from getting worse.
The ingredients in MEFENAMIC ACID are:
Medicinal ingredients: Mefenamic acid
Non-medicinal ingredients: Colloidal silicon dioxide, croscarmellose sodium, microcrystalline cellulose, sodium lauryl sulfate, stearic acid and talc.
Capsule shell: D&C yellow #10, FD&C Blue #1, FD&C yellow #6, gelatin and titanium dioxide.
Black edible ink: D&C yellow #10 aluminum lake, FD&C blue #1 aluminum lake, FD&C blue #2 aluminum lake, FD&C red #40 aluminum lake, iron oxide black, propylene glycol and shellac.
MEFENAMIC ACID comes in the following dosage forms:
Capsule: 250 mg
Do not use MEFENAMIC ACID if:
- you are allergic to mefenamic acid or any of the other ingredients in this medicine.
- you have developed asthma, hives, growths in your nose, sinus swelling or symptoms of an allergic reaction after taking acetylsalicylic acid (ASA) or other NSAIDs.
- you have recently had or are planning to have heart bypass surgery.
- you have severe, uncontrolled heart failure.
- you have bleeding in the brain or have other bleeding disorders.
- you are pregnant and in a later stage of pregnancy (28 weeks or later).
- you are currently breastfeeding (or planning to breastfeed).
- you have active stomach or intestinal ulcers.
- you have active bleeding from the stomach or gut.
- you have inflammatory bowel disease (Crohn’s Disease or Ulcerative Colitis).
- you have liver disease (active or severe).
- you have kidney disease (severe or worsening).
- you have high potassium in the blood.
- you are under 18 years old.
To help avoid side effects and ensure proper use, talk to your healthcare professional before you take MEFENAMIC ACID. Talk about any health conditions or problems you may have, including if you:
- have a condition that makes you frail or weak.
- have or have had a heart attack, chest pain, heart disease, stroke or heart failure.
- have high blood pressure, high cholesterol, diabetes or are on a low sugar diet.
- have a condition called atherosclerosis, this is when fats and cholesterol build up in your arteries.
- have poor blood flow to your extremities (like your hands and feet).
- smoke or used to smoke.
- have liver or kidney problems, urine problems or are dehydrated.
- are on a low-salt diet.
- have history of ulcer or bleeding from the stomach or gut (small or large intestines).
- drink a lot of alcohol.
- have history of bleeding in the brain.
- have bleeding or blood problems.
- have immune system problems.
- have asthma.
- are older then 65 yeas of age.
- are pregnant, planning on becoming or become pregnant while taking MEFENAMIC ACID.
- have had difficulty conceiving in the past.
- are taking any other NSAID medicines including acetylsalicylic acid (ASA).
Other warnings you should know about:
Serious Side Effects: MEFENAMIC ACID can cause serious side effects, including:
Blood and Bleeding Problems: MEFENAMIC ACID can cause blood problems, bleeding and prolonged bleeding. Taking MEFENAMIC ACID with the following medicines can increase the risk of bleeding:
- anticoagulants (prevent blood clots), corticosteroids (anti-inflammatory) or antidepressants like selective serotonin reuptake inhibitors (SSRIs).
Serious Skin Reactions: In rare cases, serious or life-threatening skin reactions listed below have been reported with some NSAIDs, such as MEFENAMIC ACID.
- Drug reaction with eosinophilia and systemic symptoms (DRESS)
- Stevens-Johnson syndrome (SJS),
- toxic epidermal necrolysis (TEN),
- exfoliative dermatitis,
- erythema multiforme,
- fixed drug eruption (FDE) and
- generalized bullous fixed drug eruption (GBFDE)
You may be at a greater risk of experiencing a serious skin reaction usually during the first month of treatment. See the Serious side effects and what to do about them table, below, for more information on these and other serious side effects.
Check-Ups and Testing: You will have regular visits with your healthcare professional during your treatment with MEFENAMIC ACID to monitor your health. They will:
- check your blood pressure.
- check your eyes. MEFENAMIC ACID can cause blurred or reduced vision.
- do blood and urine tests to check your liver, kidney and blood health.
Surgery: Tell any doctor, dentist, pharmacist or healthcare professional that you see that you are taking this medicine. This is especially important if you are planning to have heart surgery.
Driving and Using Machines: MEFENAMIC ACID may cause blurred vision, hearing problems, drowsiness, or dizziness. Be careful about driving or participating in activities that require you to be alert. If you become drowsy, dizzy or light-headed after taking MEFENAMIC ACID, do NOT drive or operate machinery.
Fertility in Women: MEFENAMIC ACID may affect your fertility. This means that it may be difficult for you to have a child. If you have trouble having a child, you might need to stop taking MEFENAMIC ACID. Talk to your healthcare professional if you have questions about this.
Adults (65 years or older): Side effects like gastrointestinal problems may happen more often. Your healthcare professional might have you start with a lower dose of MEFENAMIC ACID. They will monitor your health during and after treatment.
Tell your healthcare professional about all the medicines you take, including any drugs, vitamins, minerals, natural supplements or alternative medicines.
The following may interact with MEFENAMIC ACID:
- Alcohol.
- Acetylsalicylic Acid (ASA) or other NSAIDs, used to treat pain, fever and inflammation like celecoxib, diclofenac, ibuprofen, naproxen.
- Corticosteroids, such as prednisone, used to treat inflammation.
- Medicines used as blood thinners to prevent blood clots like warfarin, ASA, clopidogrel.
- Medicines used to treat high blood pressure like enalapril, ramipril, candesartan, irbesartan, propranolol, atenolol.
- Medicines used to lower the risk of organ rejection like cyclosporine, tacrolimus.
- Medicines used to lower extra fluid levels (diuretics), like furosemide.
- Medicines used to treat depression (antidepressants) like citalopram, fluoxetine, paroxetine, and sertraline.
- Lithium, used to treat mania that is part of bipolar disorder (manic-depressive illness).
- Medicines used to treat different cancers, like methotrexate, pemetrexed.
- Medicines used to treat diabetes, like sulphonyl urea or other oral hypoglycemics like glibenclamide, metformin, chlorpropamide or phenformin, tolbutamide.
- Medicines used to treat bacterial infections (antibiotics), like sulphonamide.
- Medicines used to treat seizures like phenytoin, hydantoin.
- Antacids containing magnesium hydroxide, used to relieve heartburn and indigestion.
- Digoxin, used in the treatment of congestive heart failure.
How to take MEFENAMIC ACID:
- Take MEFENAMIC ACID only as directed by your healthcare professional. Do NOT take more of it, do NOT take it more often and do NOT take it for a longer period of time than your healthcare professional recommended. Taking too much MEFENAMIC ACID may increase your chances of unwanted and sometimes dangerous side effects, especially if you are elderly, have other diseases or take other medications.
Take MEFENAMIC ACID by mouth, preferably with food.
- If you will be using MEFENAMIC ACID for more than 7 days, see your healthcare professional regularly to discuss whether this medicine is working for you and if it is causing any side effects.
- This medication has been prescribed specifically for you. Do NOT give it to anyone else. It may harm them, even if their symptoms seem to be similar to yours.
- Capsules should be swallowed whole. Do NOT open, divide, crush, or chew the capsules.
Usual dose:
Adults 18 years and older:
Your healthcare professional will decide on the best dosage for you based on your condition. They may lower your dose, stop your treatment for a period of time or recommend that you stop treatment completely. This may happen if you experience serious side effects, or if your disease gets worse.
For acute pain and headache:
- The usual dose is 2 capsules (500 mg) with meals, followed by 1 capsule (250 mg) every 6 hours as needed.
- The maximum dose is 5 capsules (1250 mg) per day.
- Maximum duration of treatment: 7 days.
For relief of cramping pain that comes before or during a period:
- The usual dose is 2 capsules (500 mg) with meals, followed by 1 capsule (250 mg) every 6 hours.
- The maximum dose is 5 capsules (1250 mg) per day.
- Maximum duration of treatment: 3 days.
Overdose:
| If you think you, or a person you are caring for, have taken too much MEFENAMIC ACID, contact a healthcare professional, hospital emergency department, regional poison control centre or Health Canada's toll-free number, 1-844 POISON-X (1-844-764-7669) immediately, even if there are no signs or symptoms. |
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Missed dose:
If a dose is missed, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.
Possible side effects from using MEFENAMIC ACID:
These are not all the possible side effects you may have when taking MEFENAMIC ACID. If you experience any side effects not listed here, tell your healthcare professional.
Side effects may include:
- Nausea, vomiting, diarrhea, constipation, stomach upset/abdominal pain, heartburn, indigestion, feeling gassy
- Headache, dizziness, drowsiness, light-headedness
- Loss of appetite
- Confusion, hard to concentrate or think, short-term memory loss
- Nervousness, trouble sleeping
- Bruises
- Sweating
- Skin rash
- Thirst, dry mouth
- Mouth sores
- Hair loss
Serious side effects and what to do about them
| Frequency/Side Effect/Symptom | Talk to your healthcare professional | Stop taking this drug and get immediate medical help | |
|---|---|---|---|
| Frequency/Side Effect/Symptom | Talk to your healthcare professional | Stop taking this drug and get immediate medical help | |
| Frequency/Side Effect/Symptom | Talk to your healthcare professional | Stop taking this drug and get immediate medical help | |
| Frequency/Side Effect/Symptom | Talk to your healthcare professional | Stop taking this drug and get immediate medical help | |
| Frequency/Side Effect/Symptom | Talk to your healthcare professional | Stop taking this drug and get immediate medical help | |
| Only if severe | In all cases | ||
| Only if severe | In all cases | ||
| Only if severe | In all cases | ||
| Only if severe | In all cases | ||
| Only if severe | In all cases | ||
| Common | |||
| Cystitis (bladder infection): increased need to urinate, pain in the pelvis or lower back, frequent urination during the night, cloudy urine that may contain blood, burning or pain urinating | ✓ | ||
| Gastrointestinal (GI) problems (bleeding, blockage, holes, ulcers or inflammation in your GI tract): blood in vomit, black tarry or bloody stool, dizziness, stomach pain, bloating, loss of appetite, weight loss, nausea, vomiting, constipation or diarrhea, chills or fever | ✓ | ||
| Tinnitus (hearing problems): ringing, buzzing, clicking or hissing in the ears, loss of hearing | ✓ | ||
| Uncommon | |||
| Anaphylaxis/hypersensitivity (severe allergic reaction): sudden wheeziness and chest pain or tightness, swelling of the eyelids, face, lips, tongue or throat, swelling or anaphylactic reaction/shock | ✓ | ||
| Aseptic meningitis (inflammation of the protective lining of the brain that is not caused by infection): headaches, stiff neck, nausea, vomiting, fever or clouding of consciousness | ✓ | ||
| Blood problems (low white and/or red blood cell or platelet count): feeling tired or weak, pale skin, bruising or bleeding | ✓ | ||
| for longer than usual after you hurt yourself, fever, chills | |||
| Congestive heart failure (heart does not pump blood as well as it should): shortness of breath, fatigue and weakness, swelling in ankles, legs and feet, cough, fluid retention, lack of appetite, nausea, rapid or irregular heartbeat, reduced ability to exercise | ✓ | ||
| Depression (sad mood that will not go away): difficulty sleeping or sleeping too much, changes in appetite or weight, reduced sex drive and thoughts of death or suicide | ✓ | ||
| Eye problems: blurred vision, loss of vision in eye, increased sensitivity of the eyes to light, eye pain or redness | ✓ | ||
| Hypertension (high blood pressure): fatigue, dizziness or fainting, chest pain | ✓ | ||
| Kidney disorder/problems (including kidney failure): nausea, vomiting, fever, swelling of extremities, fatigue, thirst, dry skin, irritability, dark urine, increased or decreased urine output, blood in the urine, rash, weight gain (from retaining fluid), loss of appetite, mental status changes (drowsiness, confusion, coma) | ✓ | ||
| Liver problems (including hepatitis, liver failure, cholestasis): yellowing of your skin and eyes (jaundice), right | ✓ | ||
| upper stomach area pain or swelling, nausea or vomiting, unusual dark urine, unusual tiredness | |||
| Lung problems, asthma: increased shortness of breath, wheezing, difficulty breathing, cough and chest tight ness, irregular heartbeat | ✓ | ||
| Myocardial infarction (heart attack): pressure or squeezing pain between the shoulder blades, in the chest, jaw, left arm or upper abdomen, shortness of breath, dizziness, fatigue, light-headedness, clammy skin, sweating, indigestion, anxiety, feeling faint and possible irregular heartbeat | ✓ | ||
| Stroke (bleeding or blood clot in the brain): sudden numbness, weakness or tingling of the face, arm, or leg, particularly on one side of the body, sudden headache, blurry vision, difficulty swallowing or speaking, lethargy, dizziness, fainting, vomiting, trouble understanding, trouble with walking and loss of balance | ✓ | ||
| Vertigo (a sense of severe spinning, dizziness, light-headedness) | ✓ | ||
| Rare | |||
| Serious Skin Reactions: fever, severe rash, swollen lymph glands, flu-like feeling, blisters and peeling skin that may start | ✓ | ||
| in and around the mouth, nose, eyes and genitals and spread to other areas of the body, swelling of face and/or legs, yellow skin or eyes, shortness of breath, dry cough, chest pain or discomfort, feeling thirsty, urinating less often, less urine or dark urine | |||
If you have a troublesome symptom or side effect that is not listed here or becomes bad enough to interfere with your daily activities, tell your healthcare professional.
Reporting Side Effects
You can report any suspected side effects associated with the use of health products to Health Canada by:
NOTE: Contact your healthcare professional if you need information about how to manage your side effects. The Canada Vigilance Program does not provide medical advice. |
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Storage:
Store at room temperature 15°C - 30°C. Protect from moisture.
Do NOT keep outdated medicine or medicine no longer needed. Any outdated or unused medicine should be returned to your pharmacy.
Keep out of reach and sight of children.
If you want more information about MEFENAMIC ACID:
- Talk to your healthcare professional.
Find the full product monograph that is prepared for healthcare professionals and includes this Patient Medication Information by visiting the Health Canada Drug Product Database website (https://www.canada.ca/en/health-canada/services/drugs-health-
- products/drug-products/drug-product-database.html); the manufacturer’s website (http://www.apotex.ca/products), or by calling 1-800-667-4708.
Date of Authorization: 2026-10-08