mefenamic acid

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).

If you are taking this drug on a regular schedule (not "as needed") and you miss a dose, 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.

Read the Medication Guide provided by your pharmacist before you start using mefenamic acid and each time you get a refill. If you have any questions, consult your doctor or pharmacist. Take this medication by mouth, usually 4 times a day with a full glass of water (8 ounces or 240 milliliters) or as directed by your doctor. Do not lie down for at least 10 minutes after taking this drug. If stomach upset occurs, take this medication 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 this medication 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. This medication 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 this medication 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.

Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with them first. This drug should not be used with the following medications because very serious interactions may occur: cidofovir, ketorolac. If you are currently using either of the medications listed above, tell your doctor or pharmacist before starting mefenamic acid. Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: anti-platelet drugs (e.g., cilostazol, clopidogrel), oral bisphosphonates (e.g., alendronate), "blood thinners" (e.g., enoxaparin, heparin, warfarin), corticosteroids (e.g., prednisone), cyclosporine, desmopressin, fluconazole, drugs for high blood pressure (including ACE inhibitors such as captopril, angiotensin II receptor antagonists such as losartan, and beta blockers such as metoprolol), lithium, methotrexate, pemetrexed, probenecid, SSRI antidepressants (e.g., fluoxetine, sertraline), tenofovir, "water pills" (diuretics such as furosemide, hydrochlorothiazide, triamterene). Check all prescription and nonprescription medicine labels carefully for other pain/fever drugs (NSAIDs such as aspirin, celecoxib, ibuprofen). These drugs are similar to this medication, so taking one of these drugs while also taking this medication may increase your risk of side effects. However, if your doctor has prescribed low doses of aspirin to prevent heart attack or stroke (usually at dosages of 81-325 milligrams a day), you should continue to take the aspirin. Daily use of NSAIDs (e.g., ibuprofen) may decrease aspirin's ability to prevent heart attack/stroke. Consult your doctor or pharmacist for more details and to discuss other possible treatments (e.g., acetaminophen) for your pain/fever. This medication may interfere with certain laboratory tests (e.g., urine bile test), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug. This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.

Do not share this drug with others. Laboratory and/or medical tests (e.g., blood pressure, complete blood count, liver and kidney function tests) may be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.

If overdose is suspected, contact your local poison control center or emergency room immediately. US residents should call the US National Poison Hotline at 1-800-222-1222. Canada residents should call a provincial poison control center. Symptoms of overdose may include: severe stomach pain, vomit that looks like coffee grounds, extreme drowsiness, slow/shallow breathing, seizures.

Before taking mefenamic acid, tell your doctor or pharmacist if you are allergic to it; or to aspirin or other NSAIDs (e.g., ibuprofen, naproxen, celecoxib); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: aspirin-sensitive asthma (a history of worsening breathing with runny/stuffy nose after taking aspirin or other NSAIDs, severe kidney disease, recent heart bypass surgery (CABG), active bleeding/sores in stomach/intestines (ulcer, gastrointestinal bleeding). Before using this medication, tell your doctor or pharmacist your medical history, especially of: asthma, bleeding/clotting problems, blood disorders (e.g., anemia), high blood pressure, a severe loss of body water (dehydration), diabetes, heart disease (e.g., congestive heart failure, history of heart attack), kidney disease, liver disease, growths in the nose (nasal polyps), obesity, tobacco use, history of stomach/intestine/esophagus problems (e.g., bleeding, ulcers, recurring heartburn), stroke, swelling of the ankles/feet/hands. Before having surgery, tell your doctor or dentist that you are using this medication. This drug may make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Avoid alcoholic beverages. This medicine may cause stomach bleeding. Daily use of alcohol and tobacco, especially when combined with this medicine, may increase your risk for stomach bleeding. Limit alcohol and stop smoking. Consult your doctor or pharmacist for more information. This medication may make you more sensitive to the sun. Avoid prolonged sun exposure, tanning booths, or sunlamps. Use a sunscreen and wear protective clothing when outdoors. Kidney function declines as you grow older. This medication is removed by the kidneys. Therefore, caution is advised when using this drug in the elderly because they may be more sensitive to its side effects, especially stomach bleeding and kidney effects. During the first 6 months of pregnancy, this medication should be used only when clearly needed. It is not recommended for use during the last 3 months of pregnancy due to possible harm to the unborn baby and interference with normal labor/delivery. Discuss the risks and benefits with your doctor. This drug passes into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breast-feeding.

Store at room temperature between 68-77 degrees F (20-25 degrees C) away from light and moisture. Brief storage between 59-86 degrees F (15-30 degrees C) is permitted. Do not store in the bathroom. Keep all medicines away from children and pets. Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

See also Warning section. Upset stomach, nausea, heartburn, dizziness, drowsiness, diarrhea, and headache may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor immediately if any of these unlikely but serious side effects occur: fainting, persistent/severe headache, hearing changes (e.g., ringing in the ears), fast/pounding heartbeat, mental/mood changes, stomach pain, difficult/painful swallowing, swelling of the ankles/feet/hands, sudden/unexplained weight gain, vision changes. Stop taking mefenamic acid and tell your doctor immediately if any of these rare but very serious side effects occur: easy bruising/bleeding, signs of infection (e.g., fever, persistent sore throat), unexplained stiff neck, change in the amount/color of urine. This drug may rarely cause serious, possibly fatal liver disease. If you notice any of the following rare but very serious side effects, stop taking mefenamic acid and consult your doctor or pharmacist immediately: persistent nausea/vomiting, severe stomach/abdominal pain, extreme/unusual tiredness, weakness, dark urine, yellowing eyes/skin. A very serious allergic reaction to this drug is rare. However, stop taking mefenamic acid and immediately seek medical attention if you notice any of the following symptoms of a serious allergic reaction: rash/blisters, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Nonsteroidal anti-inflammatory drugs (including mefenamic acid) may rarely increase the risk for a (sometimes fatal) heart attack or stroke. This effect does not apply to low-dose aspirin. (See Drug Interactions section.) The risk may be greater in people with heart disease or increased risk for heart disease (e.g., due to high blood pressure, diabetes), or with longer use. This drug should not be taken right before or after heart bypass surgery (CABG). Also, this drug may infrequently cause serious (rarely fatal) bleeding from the stomach or intestines. This bleeding can occur without warning symptoms at any time during treatment. Stop taking this medication and seek immediate medical attention if you notice any of the following rare but very serious side effects: chest pain, severe dizziness, trouble breathing, weakness on one side of the body, sudden vision changes, slurred speech, black stools, persistent stomach/abdominal pain, vomit that looks like coffee grounds. (See also Precautions section.) Talk with your doctor or pharmacist about the risks and benefits of treatment with this medication.