See also Warning section.

Mefenamic acid is used for the short-term relief of mild to moderate pain from various conditions such as headache, dental pain, menstrual cramps, and muscle aches.

Mefenamic acid is known as a nonsteroidal anti-inflammatory drug (NSAID). It works by blocking your body's production of certain natural substances that cause inflammation. This effect helps to decrease swelling, pain, or fever.

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.

This medication may also be used for arthritis and gout attacks.

Read the Medication Guide provided by your pharmacist before you start taking mefenamic acid and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth as directed by your doctor, usually 4 times a day. Take this medication with a full glass of water (8 ounces/240 milliliters) unless your doctor directs you otherwise. Do not lie down for at least 10 minutes after taking this medication. If stomach upset occurs while taking this medication, take it 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.

The dosage and length of treatment are based on your medical condition and response to treatment. 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 or use this drug more often or for longer than prescribed. This medication usually should not be taken for more than 7 days at a time. Discuss the risks and benefits with your doctor or pharmacist.

If you are taking this drug "as needed" (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 pain has 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.

Tell your doctor if your condition lasts or gets worse.

See also Warning section.

Upset stomach, nausea, diarrhea, dizziness, drowsiness, or blurred vision may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor 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.

This medication may raise your blood pressure. Check your blood pressure regularly and tell your doctor if the results are high.

Tell your doctor right away if you have any serious side effects, including:

• hearing changes (such as ringing in the ears)
• mental/mood changes
• easy bleeding/bruising
• difficult/painful swallowing
• signs of kidney problems (such as change in the amount of urine, pink/bloody urine)
• symptoms of heart failure (such as swelling ankles/feet, unusual tiredness, unusual/sudden weight gain)

Mefenamic acid may rarely cause serious (possibly fatal) liver disease. Get medical help right away if you have any symptoms of liver damage, including:

• nausea/vomiting that doesn't stop
• loss of appetite
• stomach/abdominal pain
• yellowing eyes/skin
• dark urine

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• fever
• swollen lymph nodes
• rash
• 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 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

See also Warning section.

Before taking mefenamic acid, tell your doctor or pharmacist if you are allergic to it; or to aspirin or other NSAIDs (such as 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.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• asthma (including a history of worsening breathing after taking aspirin or other NSAIDs)
• bleeding/clotting problems
• blood disorders (such as anemia)
• growths in the nose (nasal polyps)
• heart disease (such as previous heart attack)
• high blood fat levels (cholesterol/triglyceride)
• high blood pressure
• liver disease
• stroke
• swelling (edema, fluid retention)
• stomach/intestinal/esophagus problems (such as bleeding, heartburn, ulcers)

Kidney problems can sometimes occur with the use of NSAID medications, including mefenamic acid. Problems are more likely to occur if you are dehydrated, have heart failure or kidney disease, are an older adult, or if you take certain medications (see also Drug Interactions section). Drink plenty of fluids as directed by your doctor to prevent dehydration and tell your doctor right away if you have pink/bloody urine or any unusual change in the amount of urine.

This drug may make you dizzy, drowsy, or cause blurred vision. Alcohol or marijuana (cannabis) can worsen these effects. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

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. Ask your doctor or pharmacist about how much alcohol you may safely drink.

This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Older adults may be at greater risk for stomach/intestinal bleeding, kidney problems, heart attack, and stroke while using this drug.

Before using this medication, women of childbearing age should talk with their doctor(s) about the benefits and risks. Tell your doctor if you are pregnant or if you plan to become pregnant. This medication may harm an unborn baby and cause problems with normal labor/delivery. It is not recommended for use in pregnancy from 20 weeks until delivery. If your doctor decides that you need to use this medication between 20 and 30 weeks of pregnancy, you should use the lowest effective dose for the shortest possible time. You should not use this medication after 30 weeks of pregnancy.

This drug passes into breast milk. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug are:

• aliskiren
• ACE inhibitors (such as benazepril, lisinopril)
• angiotensin II receptor blockers (such as losartan, valsartan)
• cidofovir
• corticosteroids (such as dexamethasone, prednisone)
• lithium
• methotrexate
• "water pills" (diuretics such as furosemide)

This medication may increase the risk of bleeding when taken with other drugs that also may cause bleeding. Examples include anti-platelet drugs such as clopidogrel, "blood thinners" such as dabigatran/enoxaparin/warfarin, among others.

Check all prescription and nonprescription medicine labels carefully since many medications contain pain relievers/fever reducers (aspirin, NSAIDs such as ibuprofen, ketorolac, naproxen). These drugs are similar to mefenamic acid and may increase your risk of side effects if taken together. However, if your doctor has told you to take low-dose aspirin to prevent heart attack or stroke (usually 81-162 milligrams a day), you should keep taking the aspirin unless your doctor tells you not to. Ask your doctor or pharmacist for more details.

This medication may interfere with certain lab tests (such as urine bile test), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: severe stomach pain, slow/shallow breathing, extreme drowsiness.

Do not share this medication with others.

Lab and/or medical tests (such as complete blood count, liver/kidney function, blood pressure) may be done while you are using this medication. Keep all medical and lab appointments. Consult your doctor for more details.

If you are taking this drug on a regular schedule (not just "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. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications 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.