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Mefenamic Acid, Oral Capsule

Highlights for mefenamic acid

  1. Mefenamic acid oral capsule is available as both a generic and brand-name drug. Brand name: Ponstel.
  2. Common side effects include nausea, vomiting, upset stomach, stomach pain, diarrhea, constipation, gas, indigestion, and dizziness.
  3. Mefenamic acid is used to treat mild to moderate pain and menstrual pain (also known as dysmenorrhea).
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Important warnings

Important warnings

FDA warnings: Potentially fatal heart risks and stomach problems
  • This drug has a Black Box Warning. This is the most serious warning from the Food and Drug Administration (FDA). A black box warning alerts doctors and patients to potentially dangerous effects.
  • Mefenamic acid may increase your risk of heart problems, including blood clot, heart attack, stroke, or heart failure. These conditions can be fatal. Your risk may increase if you already have heart disease or have taken mefenamic acid for a long period of time or at high doses. You shouldn’t take mefenamic acid to treat pain before a coronary bypass graft surgery. This is a heart surgery that’s done to increase blood flow to your heart. Taking mefenamic acid around the time of your surgery will increase your risk of heart attack and stroke.
  • Mefenamic acid may increase your risk of stomach problems, such as bleeding, or small holes in the lining of your stomach or intestines (peptic ulcers). These conditions can be fatal. They can occur at any time and without any warning signs or symptoms. If you’re aged 65 years or older, you may have a greater chance for severe stomach issues.
  • Liver damage warning: Mefenamic acid may damage your liver. Your doctor may take a blood test to monitor your liver and make sure this drug is safe for you. Call your doctor immediately if you notice symptoms of liver damage, such as:
    • nausea
    • tiredness
    • itching
    • yellowing of your skin or whites or your eyes
    • pain in your upper stomach
    • flu-like symptoms, such as fever, chills, and body aches
  • Dangerous skin reactions warning: Get emergency medical help right away if you experience:
    • a severe skin reaction
    • rash that is red, swollen, peeling, or blistered
    This might be a severe skin disorder such as exfoliative dermatitis, Stevens-Johnson syndrome, or toxic epidermal necrolysis, which can be fatal.
  • Pregnancy warning: You shouldn’t use mefenamic acid in the third trimester of pregnancy. It may cause the blood vessel that supplies nutrients and oxygen to the fetus to close too early.

About

What is mefenamic acid?

Mefenamic acid is a prescription drug that’s available as the brand-name drug Ponstel. It’s also available as a generic drug. Generic drugs usually cost less. In some cases, they may not be available in every strength or form as the brand.

Why it's used

Mefenamic acid is used to treat mild to moderate pain and menstrual cramps. It’s approved to treat pain in people who are least 14 years old for no longer than 7 days. It’s approved to treat menstrual cramps for no longer than 2–3 days.

How it works

Mefenamic acid belongs to a class of drugs called nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs help reduce pain, inflammation, and fever.

It isn’t known how this medication works to decrease pain. It may help reduce swelling by lowering levels of prostaglandin, a hormone-like substance that usually causes inflammation.

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Side effects

Mefenamic acid side effects

Mefenamic acid oral capsule doesn’t cause drowsiness. However, it can cause other side effects.

Most common side effects

The most common side effects that occur with mefenamic acid include:

  • stomach pain
  • nausea
  • vomiting
  • heartburn
  • constipation
  • diarrhea
  • rash
  • dizziness
  • ringing in your ear (tinnitus)

Mild side effects may go away within a few days or a couple of weeks. Talk to your doctor or pharmacist if they’re more severe or don’t go away.

Serious side effects

Call your doctor right away if you have serious side effects. call 911 if your symptoms feel life-threatening or if you think you’re experiencing a medical emergency. Serious side effects and their symptoms can include the following:

  • heart attack or stroke. Symptoms may include:
    • chest pain
    • shortness of breath
    • weakness on one side of your body
    • slurred speech
  • heart failure. Symptoms may include:
    • unusual weight gain
    • swelling in your arms, legs, hands, or feet
  • stomach problems, such as ulcers or bleeding. Symptoms may include:
    • stomach pain or upset stomach
    • black, sticky stools
    • vomiting up blood
  • liver problems. Symptoms may include:
    • yellowing of your skin or whites of your eyes
    • flu-like symptoms, such as fever, chills, and body aches
    • tiredness
    • nausea
    • pain in the upper part of your stomach
    • itching
  • skin reactions. Symptoms may include:
    • reddening, blistering, or peeling skin
  • allergic reactions. Symptoms may include:
    • shortness of breath
    • swelling of your face, lips, or throat

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.

Interactions

Mefenamic acid may interact with other medications

Mefenamic acid oral capsule may interact with other medications, herbs, or vitamins you might be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Note: You can reduce your chances of drug interactions by having all of your prescriptions filled at the same pharmacy. That way, a pharmacist can check for possible drug interactions.

Examples of drugs that can cause interactions with mefenamic acid are listed below.

Blood pressure drugs

  • angiotensin-converting enzyme (ACE) inhibitors
  • angiotensin receptor blockers
  • beta-blockers

Mefenamic acid may decrease the blood pressure-lowering effects of these drugs.

Diuretics (water pills)

Mefenamic acid can decrease the effectiveness of medications used to get rid of extra fluid in your body.

Nonsteroidal anti-inflammatory drugs

These include:

  • aspirin
  • ibuprofen
  • naproxen

Combining these medications may increase your risk of stomach bleeding and ulcers.

Anticoagulant, blood thinners, and drugs that affect serotonin

  • warfarin
  • selective serotonin reuptake inhibitors (SSRIs)

Taking these medications with mefenamic acid increases your risk of serious stomach bleeding.

Bipolar disorder drug

  • lithium

Mefenamic acid may increase the amount of lithium in your body, which could be toxic. Your doctor may monitor for signs of lithium poisoning, such as nausea, vomiting, diarrhea, tremors, or confusion.

Disease-modifying antirheumatic drug

  • methotrexate

Mefenamic acid may increase the amount of methotrexate in your body, which may increase side effects of methotrexate.

Antacid

  • magnesium hydroxide (milk of magnesia)

Magnesium hydroxide may increase mefenamic acid levels in your body, which could increase its side effects.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

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Other warnings

Mefenamic acid warnings

Mefenamic acid oral capsule comes with several warnings.

Allergy warning

Mefenamic acid can cause a severe allergic reaction. Symptoms may include:

  • trouble breathing
  • swelling of your face or throat
  • hives

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal.

Don’t take this medication if you’re allergic to aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs). These include ibuprofen, naproxen, diclofenac, and meloxicam.

Alcohol interaction

Combining alcohol with mefenamic acid increases your risk of stomach bleeding or ulcer.

Warnings for people with certain health conditions

For people with heart disease: This includes heart failure and high blood pressure. Mefenamic acid may cause an increased risk of heart problems, including heart attack, stroke, or blood clot. Your risk may be higher if you already have heart disease and take the medication for a longer period of time. Mefenamic acid may cause you to retain water and can make high blood pressure worse or increase your risk of heart failure.

For people with ulcers and stomach bleeding: Mefenamic acid increases your risk of bleeding or ulcers in your stomach or intestines. These can occur at any time and without any warning signs or symptoms. You’re at a greater risk for serious stomach and intestinal bleeding if you’re older than 65 years, drink alcohol, or smoke cigarettes. Tell your doctor if you currently have stomach ulcer or bleeding, or if you’ve had one in the past.

For people with asthma: Mefenamic acid may cause your airways to become narrower or smaller, which can be deadly. If your asthma gets worse, get emergency medical help. If you have asthma that’s sensitive to aspirin or NSAIDs, you shouldn’t take this medication at all.

For people with kidney disease: Mefenamic acid can damage your kidneys if you take it for a long period of time. Tell your doctor if you have a history of kidney disease.

Warnings for other groups

For pregnant women: Mefenamic acid has not been sufficiently studied in pregnant women. Speak with your doctor if you’re pregnant or plan to become pregnant.

Women who are breastfeeding: Small amounts of mefenamic acid may be passed into your breast milk and cause side effects in your child. You and your doctor may need to decide whether you’ll stop breastfeeding or stop taking mefenamic acid.

For seniors: If you’re older than 65 years, your body may clear this drug more slowly. This can lead to a buildup of the drug in your body and increase your risk of side effects. Your doctor may monitor your kidneys while you take mefenamic acid to make sure it’s still safe for you.

For children: The safety and effectiveness of mefenamic acid haven’t been established in people younger than 14 years.

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Dosage

How to take mefenamic acid

This dosage information is for mefenamic acid oral capsule. All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

Forms and strengths

Generic: Mefenamic acid

  • Form: Oral Capsule
  • Strength: 250 mg

Brand: Ponstel

  • Form: Oral Capsule
  • Strength: 250 mg

Dosage for mild to moderate pain

Adult dosage (ages 18 years and older)

  • The first dose is 500 mg. After that, take 250 mg every 6 hours as needed.
  • You shouldn’t take mefenamic acid for longer than 7 days.

Child dosage (ages 14-17 years)

  • The first dose is 500 mg. After that, take 250 mg every 6 hours as needed.
  • You shouldn’t take mefenamic acid for longer than 7 days.

Child dosage (ages 0-13 years)

Dosage for people younger than 14 years hasn’t been established.

Dosage for menstrual pain

Adult dosage (ages 18 years and older)

  • Start this medication when your bleeding and symptoms start.
  • The first dose is 500 mg. After that, take 250 mg every 6 hours as needed.
  • You shouldn’t take mefenamic acid for longer than 3 days.

Child dosage (ages 14-17 years)

  • Start this medication when your bleeding and symptoms start.
  • The first dose is 500 mg. After that, take 250 mg every 6 hours as needed.
  • You shouldn’t take mefenamic acid for longer than 2–3 days.

Child dosage (ages 0-13 years)

Dosage for people younger than 14 years hasn’t been established.

Special considerations

Liver problems: If you have liver disease, your body might not be able to process this drug well. This may cause increased amounts of mefenamic acid in your blood and increase your risk of side effects. Your doctor may decrease your dose.

Kidney problems: If you have kidney disease, your body might not be able to clear out this drug as well as it should. This may cause increased amounts of mefenamic acid in your blood and increase your risk of side effects. Your doctor may decrease your dose.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.

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Take as directed

Take as directed

Mefenamic acid oral capsule is a short-term medication. If you’re using it for mild to moderate pain, treatment usually lasts no longer than 7 days. If you’re using it for menstrual cramps, treatment usually lasts no longer than 2–3 days. This drug comes with serious risks if you don’t take it as prescribed.

If you don’t take it at all or miss doses: If you don’t take mefenamic acid or miss your doses, your pain may not go away.

If you take too much: If you take too much mefenamic acid, you may experience:

  • drowsiness
  • nausea
  • vomiting
  • stomach pain
  • stomach bleeding
  • high blood pressure
  • kidney failure
  • slowed breathing
  • coma

Get medical attention immediately if you take or think you’ve taken too much mefenamic acid.

What to do if you miss a dose: This medication is taken every 6 hours as needed. If you planned to take it and missed a dose, take it as soon as you can. After you take it, wait another 6 hours for the next dose. Don’t take more than one capsule to make up for a missed dose. This could result in toxic side effects.

How can I tell if the drug is working?: You may be able to tell this drug is working if you experience less pain.

Important considerations

Important considerations for taking mefenamic acid

Keep these considerations in mind if your doctor prescribes mefenamic acid oral capsule for you.

General

  • You can take mefenamic acid with food to avoid upset stomach.
  • Don’t crush or chew the oral capsule. Swallow it whole.
  • Not every pharmacy stocks this drug, so call ahead.

Storage

  • Store mefenamic acid at room temperature: 68–77°F (20–25°C).
  • Keep it in the container given to you at the pharmacy, and keep it tightly closed.
  • Keep your drugs away from areas where they could get wet, such as bathrooms. Store them away from moisture and damp locations.

Refills

A prescription for this medication is refillable. You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry it with you or in your carry-on bag.
  • Don’t worry about airport X-ray machines. They can’t hurt this medication.
  • You may need to show your pharmacy’s preprinted label to identify the medication. Keep the prescription-labeled box with you when traveling.

Clinical monitoring

Your doctor may perform:

  • blood tests to check for possible bleeding
  • liver function tests to make sure mefenamic acid isn’t harming your liver
  • kidney function tests to make sure mefenamic acid isn’t harming your kidneys

Insurance

Many insurance companies will require a prior authorization before they approve the prescription and pay for mefenamic acid.

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Alternatives

Are there any alternatives?

There are other drugs available to treat your condition. Some may be more suitable for you than others. Talk to your doctor about possible alternatives.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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