Uses
What is mefenamic acid used for?
Mefenamic acid is commonly used to treat mild to moderate pain, including pain caused by menstrual cramps.
Mefenamic acid may also be used for other conditions as determined by your healthcare provider.
How does mefenamic acid work (mechanism of action)?
Mefenamic acid works by blocking certain substances in the body that cause pain, inflammation, and fever.
How is mefenamic acid supplied (dosage forms)?
Mefenamic acid is available in the following dosage forms that are taken by mouth.
- 250 mg oral capsules
How should I store mefenamic acid?
Mefenamic acid should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C), for shorter periods of time, such as when transporting it. Store in a cool, dry place in a tightly closed container.
Side Effects
What are the most common side effects of mefenamic acid?
The most common side effects of mefenamic acid are listed below. Tell your healthcare provider if you have any of these side effects that bother you.
- Upset stomach or stomach pain
- Constipation or diarrhea
- Gas or heartburn
- Nausea and vomiting
- Dizziness
- Headaches
- Skin rash or itching
There may be other side effects of mefenamic acid that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of mefenamic acid?
While less common, the most serious side effects of mefenamic acid are described below, along with what to do if they happen.
Severe Allergic Reactions. Mefenamic acid can cause allergic reactions, including a specific type of allergic reaction called DRESS. DRESS stands for Drug Reaction with Eosinophilia and Systemic Symptoms. It is also sometimes called multiorgan hypersensitivity. This is a reaction that can affect multiple parts of the body, including your liver, kidneys, and heart. Stop taking the medicine and get help right away if you have any of the following symptoms of a serious allergic reaction.
- Breathing problems or wheezing
- Racing heart
- Fever or general ill feeling
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Trouble swallowing or throat tightness
- Itching, skin rash, or pale red bumps on the skin called hives
- Nausea or vomiting
- Dizziness, feeling lightheaded, or fainting
- Stomach cramps
- Joint pain
- Dark colored urine
- Your skin or the whites of your eyes turning yellowish in color (also called jaundice)
Heart Attack and Stroke. Mefenamic acid can increase your risk of a heart attack or stroke that can lead to death. This risk is increased in people with existing heart disease and with longer use of mefenamic acid and higher doses. Do not take mefenamic acid if you have had a recent heart attack without talking to your healthcare provider. This could increase your risk of having another heart attack. Get emergency help if you have any of the following symptoms of a heart attack or stroke.
- Chest pain or pressure
- Fast or abnormal heartbeat
- Trouble breathing
- Pain in your back, jaw, throat, or arm
- Sweating, upset stomach, vomiting, or dizziness
- Sudden weakness on one side of your body
- Sudden and severe headache
- Slurred speech or trouble understanding speech
Bleeding. Mefenamic acid can increase your risk of bleeding, especially if you have a bleeding disorder or take other medicines that increase your risk of bleeding. Tell your healthcare provider right away if you notice signs of bleeding including easy bruising or bleeding.
Stomach Bleeding. Mefenamic acid can increase your risk of bleeding, ulcers, and tears (perforation) in your gut. The risk is higher if you have a history of stomach ulcers, or bleeding problems, take higher doses of mefenamic acid or take it for longer than directed, have poor health, are age 60 or older, have liver disease, smoke, drink alcohol, or take certain other medicines such as oral corticosteroids, anticoagulants, or nonsteroidal anti-inflammatory drugs (NSAIDs). Stop taking mefenamic acid and get emergency help right away if you have any of the following symptoms.
- Vomit blood
- Black or tarry poop
- Stomach pain that does not go away
- Upset stomach
- Feel faint
Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking mefenamic acid. Call your healthcare provider right away if you have any of the following symptoms of liver damage.
- Nausea or vomiting
- Stomach or belly pain
- Fever
- Weakness or unusual tiredness
- Itching
- Loss of appetite
- Light-colored poop
- Dark-colored urine
- Your skin or the whites of your eyes turning yellowish in color (also called jaundice)
Increased Blood Pressure (Hypertension). Mefenamic acid may increase your blood pressure or make it worse if you have a history of high blood pressure. Call your healthcare provider if your blood pressure increases while taking this medicine.
If you measure your blood pressure and the top number (systolic) is 180 mm Hg or higher or the bottom number (diastolic) is 120 mm Hg or higher, get medical attention right away. Increases in blood pressure may not be noticeable but look out for any of the following symptoms of severely high blood pressure.
- Sudden severe headache
- Chest pain
- Dizziness or confusion
- Trouble breathing
- Nausea/vomiting
- Blurry or other changes to vision
- Anxiety
- Buzzing in the ears
- Nosebleed
- Feeling of skipped heart beats
Heart Failure. Mefenamic acid may increase your risk of heart failure. Tell your healthcare provider right away if you have any of the following symptoms of heart failure.
- Shortness of breath or trouble breathing, especially while lying down
- Swelling in your feet, ankles, or legs
- Unusually fast weight gain
- Unusual tiredness
Kidney Damage. Kidney damage can happen when taking mefenamic acid. Call your healthcare provider right away if you have any of the following symptoms of kidney damage.
- Reduced need to pee
- Swelling in your feet, ankles, or legs
- Weakness or unusual tiredness
- Difficulty catching your breath or chest pain/pressure
- Confusion
- Nausea
- Seizures
Increased Potassium Level (Hyperkalemia). Mefenamic acid can increase the potassium levels in your blood (hyperkalemia), especially if your kidneys are not working as well as they should. Mild increases in potassium levels may not cause any symptoms. Stop taking the medicine and get help right away if you have any of the following symptoms of sudden high potassium levels.
- Chest pain or fast or abnormal heartbeat
- Shortness of breath
- Nausea or vomiting
- Unable to move your muscles
Severe Skin Reactions. Mefenamic acid can cause severe skin reactions called Exfoliative Dermatitis, Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) that can lead to death if not treated. If you develop a rash, stop mefenamic acid and call your healthcare provider right away. Get emergency help right away if you have any of the following symptoms of SJS or TEN.
- Painful red or purple skin that looks burned and peels off
- Flat red rash or blisters on your skin, mouth, nose, and genitals
- Red, painful, watery eyes
Anemia. Mefenamic acid may cause anemia, which is a condition that causes low levels of red blood cells. Tell your healthcare provider if you have any of the following symptoms of anemia.
- Unusual weakness or tiredness
- Cold hands and feet
- Fast or abnormal heartbeat
- Pale or yellowish skin
- Dizziness, lightheadedness, or feeling like you are about to pass out
- Shortness of breath
Warnings & Precautions
Who should not use mefenamic acid?
Allergies to Ingredients. People who are allergic to any of the following should not take mefenamic acid.
- Mefenamic acid
- Ponstel
- Aspirin or any other medicine known as a nonsteroidal anti-inflammatory drug (NSAID)
- Any of the ingredients in the specific product dispensed
Your pharmacist can tell you all of the ingredients in the specific mefenamic acid products they stock.
Heart Surgery. Do not take mefenamic acid right before or after a heart surgery called coronary artery bypass graft (CABG). Taking mefenamic acid during this time can increase your risk of heart attack or stroke.
What should I know about mefenamic acid before using it?
Do not take mefenamic acid unless it has been prescribed to you by a healthcare provider. Take it as prescribed.
Do not share mefenamic acid with other people, even if they have the same condition as you. It may harm them.
Keep mefenamic acid out of the reach of children.
You may take mefenamic acid with food or milk if stomach upset occurs.
People aged 65 years or older can be at greater risk for some side effects of mefenamic acid. Talk to your healthcare provider about your risks if you are in this age group.
What should I tell my healthcare provider before using mefenamic acid?
Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if mefenamic acid is right for you.
In particular, make sure that you discuss any of the following.
Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.
- Heart problems such as heart failure or a recent heart attack
- Stroke
- Bleeding problems
- Kidney or liver problems
- Stomach ulcers, bleeding, or other stomach problems like heartburn
- High blood pressure
- Fluid retention (edema)
- Asthma
Other Medicines and Supplements. Mefenamic acid may interact with other medicines and supplements. Before taking mefenamic acid, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section below for more details.
Pregnancy. Do not take mefenamic acid at 20 weeks or later in pregnancy without talking to your healthcare provider. Strictly avoid mefenamic acid at 30 weeks of pregnancy. Taking mefenamic acid during this time may cause harm to an unborn baby and complications during delivery. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take mefenamic acid while you are pregnant or trying to get pregnant.
Breastfeeding. Mefenamic acid passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should stop taking mefenamic acid or stop breastfeeding.
Interactions
Does mefenamic acid interact with foods or drinks?
There are no known interactions between mefenamic acid and foods or drinks.
Drinking alcohol while taking mefenamic acid increases your risk of stomach ulcers and bleeding. It is best to limit the amount of alcohol you drink.
Does mefenamic acid interact with other medicines (drug interactions)?
Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.
In particular, make sure that you discuss if you are using any of the following before taking mefenamic acid.
- A blood thinner such as warfarin, which is a medicine used to treat or prevent blood clots
- A selective serotonin reuptake inhibitor (SSRI), which is a medicine commonly used for anxiety and depression
- A serotonin norepinephrine reuptake inhibitor (SNRI), which is a medicine commonly used for anxiety and depression
- A beta-blocker, such as metoprolol (Lopressor), atenolol (Tenormin), or propranolol (Inderal LA), which is a medicine that may be used for certain heart conditions or to reduce blood pressure
- An angiotensin II receptor blocker (ARB), which is a medicine for high blood pressure, heart failure, and other heart conditions
- An angiotensin-converting enzyme (ACE) inhibitor, which is a medicine for high blood pressure, heart failure, and certain kidney problems
- A diuretic, also called a water pill, which is a medicine used to reduce edema (fluid retention) and blood pressure
- Digoxin (Lanoxin), which is a medicine used to treat irregular heartbeat and some types of heart failure
- Lithium, which is a medicine for certain mental health conditions
- Methotrexate (Trexall and others), which is a medicine commonly used for rheumatoid arthritis or certain types of cancer
- Cyclosporine (Gengraf, Neoral, Sandimmune, and others), which is a medicine to suppress your immune system
- Any nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, naproxen, and others, which are present in many prescription and OTC products for pain, swelling, and fever
- Aspirin
- Pemetrexed (Alimta, Pemfexy), which is a medicine to treat certain cancers
- An antacid containing magnesium hydroxide
This may not be a complete list of medicines that can interact with mefenamic acid. Always check with your healthcare provider.
Overdose/Missed Dose
What should I do if I accidentally use too much mefenamic acid?
If you or someone else has taken too much mefenamic acid, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.
What should I do if I miss a dose of mefenamic acid?
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.
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