Mefenamic acid: what is it and what is it indicated for? See how to use

The use of medicated substances with analgesic and anti-inflammatory action is very common, since they can help in the treatment and relief of the symptoms of several conditions – such as rheumatic diseases, inflammation in the throat, among others.

There is a wide variety of this type of medication. Thinking about it, we separated some information about one of them: mefenamic acid .

If you have never heard about this drug and / or want to know more about its indication, how it acts on the body, its side effects and several other points, check out:


What is mefenamic acid?

Mefenamic acid is a drug substance, which is present as an active ingredient in different drugs – with interchangeable, generic, similar and similar options.

It is a non-steroidal anti-inflammatory (NSAIDs), also acting as antipyretic ( fever relief ) and analgesic (pain relief).

Thus, it acts in the treatment of disorders such as:

  • Rheumatoid arthritis (chronic inflammation of the joints);
  • Osteoarthritis;
  • Pain (muscular, traumatic, dental, headache of various origins, postoperative and postpartum);
  • Primary dysmenorrhea (menstrual cramps);
  • Menorrhagia due to dysfunctional causes (intense menstrual flow without damage to the organs) or due to the use of an IUD (intrauterine device);
  • Premenstrual syndrome.
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The medications that rely on mefenamic acid are sold in a compressed version (500mg). Therefore, administration is done orally.

Although it is a substance tested and certified by ANVISA, it can cause complications if used even in cases of contraindication. Like, for example, people with Stevens Johnson Syndrome – a rare and serious disease that affects the skin and mucous membranes.

For this reason, despite the fact that the medication treats conditions considered “common”, medical follow-up is not necessary. The practice of self – medication is always contraindicated.

Is it anti-inflammatory?

-Yeah . Medicines that rely on mefenamic acid as an active ingredient are classified by ANVISA (National Health Surveillance Agency) in the anti-inflammatory category, with analgesic and antipyretic action as well.

Inflammatory control occurs through the inhibition of prostaglandins, substances that stimulate inflammation processes.

However, it should be noted that even drugs of the same therapeutic class cannot be used simultaneously or replaced without medical advice. Considering the fact that they may have different principles, adverse reactions and contraindications, for example.

What is the composition of mefenamic acid?

The Ponstan (reference product of mefenamic acid) has 500mg mefenamic acid , along with certain excipients – substances which are mixed with the drug (active ingredient) to complete the mass or volume of medication.

In the case of this remedy, the excipients are: corn starch, microcrystalline cellulose, magnesium stearate, sodium lauryl sulphate, povidone, vanillin, FDC No. 5 yellow lacquer aluminum dye, colloidal silicon dioxide.

It should be emphasized that the composition mentioned is that of the reference medicine, that is, the one that has the original formula of that medication. That’s because mefenamic acid is not the medicine itself but the active ingredient.

This means that it is present in some remedies as an active ingredient, which can be generic, similar, interchangeable similar or the reference – in this case, Ponstan.

Does mefenamic acid have ibuprofen?

No . Ibuprofen and Mefenamic acid are two medicated substances that work in the same way in the body, that is, both are anti-inflammatory and work to combat the common symptoms of these conditions (such as pain and fever).

In fact, both are classified as non-steroidal anti-inflammatory drugs (NSAIDs). Which means they are not derived from hormones.

With medical guidance, Ibuprofen and Mefenamic Acid can even replace each other without causing damage or changes in their activity in the body.

What is mefenamic acid indicated for?

According to the instructions on the package insert, mefenamic acid is indicated for the relief of symptoms of rheumatoid arthritis (including Still’s disease, a rare systemic inflammatory disease) and osteoarthritis. It also treats pain (muscle, headache, traumatic, dental, etc.) and fever .

In addition, the package insert also indicates its use for the treatment of the following conditions:

  • Primary dysmenorrhea ( menstrual cramps );
  • Menorrhagia ( excessive menstrual flow ) – when caused by dysfunctional causes or use of an IUD (intrauterine device), based on a diagnosis that rules out other causes of pelvic disease;
  • Premenstrual syndrome (PMS) – this is the popularly called PMS , a set of symptoms that affect women between ovulation and the menstrual period.

Considering its anti-inflammatory, analgesic and antipyretic (antipyretic) action, mefenamic acid can treat any condition that has an inflammatory process as a principle – which commonly causes pain and fever.

Thus, it provides relief from the symptoms of inflammation, regardless of whether the cause is a chronic disease (such as rheumatic problems), trauma (accident, fall, etc.) or other factors such as menstrual disorders.

How to use mefenamic acid?

Mefenamic acid is only available in a compressed version (500mg each), administration should be done with water and it can be taken with food in cases of gastrointestinal discomfort. In general, the recommended use is 3 times a day, for the most diverse conditions that the medication treats.

However, it is worth noting that although these are the indications provided for in the package insert, the way in which the medication is used may vary according to the case. Therefore, it is essential to seek medical advice in order to make a safe and effective use of the medication.

What is the dosage (dose)?

The recommended dose of mefenamic acid may vary according to medical advice. But, as mentioned in the previous topic, in general the administration is done 3 times a day and the dose also usually does not change.

See what the package insert is indicated for different cases:

  • Mild to moderate pain – 500mg 3 times a day;
  • Rheumatoid Arthritis and Osteoarthritis – 500mg 3 times a day;
  • Dysmenorrhea (menstrual cramps) – 500mg 3 times a day, administered only as long as the pain persists;
  • Menorrhagia (excess menstrual flow) – 500mg 3 times a day, administered when the symptom appears (persist in treatment as directed by a doctor);
  • Premenstrual syndrome (PMS) – 500mg 3 times a day for the duration of the symptoms of this disorder.

It is worth noting that the package insert informs that, in order to avoid adverse reactions, the doctor may recommend the lowest dose possible to the patient and for the shortest period of time – as long as the treatment’s effectiveness is maintained.

What to do if you forget to take a dose?

If the patient forgets to take the medication at any time, he / she can administer the dose as soon as he / she remembers. However, once this is done, you must respect the interval time for the next dose (8 hours) and do not take it according to the previous schedule.

However, if the person remembers to take the missed dose at a time close to the next, he should not administer the medicine.

In this case, wait until the indicated time and take it normally – there is no need to double the dose, making up for the one that was not ingested.

How does mefenamic acid act?

Mefenamic acid is a drug substance classified as a non-steroidal anti-inflammatory drug (NSAIDs). In addition to the effect against inflammation, it also acts in an analgesic and antipyretic (antipyretic) manner.

Thus, its action is made possible through the inhibition of prostaglandin – a group of lipids that are produced in sites of tissue damage or infection.

These substances stimulate the inflammatory process, in order to signal to the organism that there is an injury or disease in a certain area of ​​the body.

Therefore, when ingesting mefenamic acid, it inhibits its production. Consequently, it combats inflammation and its most common symptoms (pain, discomfort and fever).

Side effects

Any medication can cause side effects to those who use it. However, there is no way of knowing if this will happen and what the effects will be, so that some patients may not have any complications and others may.

According to the indications in the package insert for mefenamic acid, the common adverse reactions are:

  • Abdominal pain;
  • Diarrhea;
  • Nausea (feeling sick);
  • Vomiting.

In addition, it also shows the indication of less common reactions that can happen:

  • Anorexia (loss of appetite);
  • Jaundice (yellowish color on the skin);
  • Colitis and enterocolitis (inflammation of the intestines);
  • Constipation (constipation);
  • Flatulence (excess gas in the stomach or intestines);
  • Gastric ulceration (wound in the stomach) with or without bleeding;
  • Mild liver toxicity (destruction of liver cells);
  • Hepatitis (inflammation of the liver);
  • Hepatorenal syndrome (kidney failure in patients with previous liver failure);
  • Pyrosis (burning sensation in the esophagus);
  • Pancreatitis (inflammation of the pancreas);
  • Steatorrhea (elimination of fat in the stool).

The package insert also contains some information about rare reactions (such as Stevens-Johnson Syndrome), which occur in less than 1% of patients.

If you experience any of the listed side effects or other changes after starting treatment with this medication, discontinue its use and seek medical advice.

Do you sleep?

Among the common side effects of mefenamic acid, there is no disorder that can affect sleep – neither in terms of causing more drowsiness, nor in terms of insomnia .

However, among the very rare reactions of this medication, the package insert mentions these changes.

Therefore, if you feel more sleepy or have difficulty sleeping after taking this medication, it is ideal to see a doctor. With this, it will be possible to analyze whether the problem is (or not) linked to mefenamic acid and change the treatment if necessary.

What are the contraindications?

As indicated in the package insert, mefenamic acid is contraindicated for people who have some sensitivity to the medication, component of the formula or other similar medications.

This includes people with Stevens-Johnson Syndrome , a very rare and serious disorder that affects the skin and mucous membranes – causing ulcerations, red spots and blisters, which can cause irreversible sequelae if not treated in time.

In addition, this medication should not be administered to patients who have symptoms of bronchospasm, allergic rhinitis or urticaria. It is also not recommended for patients with active ulcer or chronic inflammation of the gastrointestinal tract.

Mefenamic acid should also be avoided in patients with pre-existing renal dysfunction.

Other conditions in which this medication is not indicated are: treatment of perioperative pain from surgery for myocardial revascularization (CABG), in patients with severe renal, hepatic or cardiac failure.

Finally, it should be noted that mefenamic acid is contraindicated for children under 14 years of age.

Prices and where to buy

As mentioned in a previous topic, mefenamic acid is the drug substance and not the medicine itself. It is present in different brands that can be found in physical and online pharmacies, as well as platforms such as Consulta Remédios .

The reference medicine is the originator of the formula – which will later be made available to other laboratories, in order for them to manufacture other versions.

It should be noted that, when a drug is created, those who develop it gain exclusive time (patent) for marketing. What is done due to the investments made during the elaboration period.

After this period, other laboratories have access to the formula and can create interchangeable generic, similar or similar versions (approved by ANVISA as a drug that can replace the reference without any change).

Next, see the price of the different remedies that rely on mefenamic acid:


The reference version of mefenamic acid is the Ponstan remedy , from the Wyeth / Pfizer laboratory.

This medicine is sold in boxes of 6, 15 or 24 tablets. Your price * may change due to this and other factors (availability, region of purchase, etc.).

But, in general, the values ​​can usually be in the following range:

  • Ponstan 500mg, box with 6 pills – around R $ 8;
  • Ponstan 500mg, box with 15 pills – around R $ 20;
  • Ponstan 500mg, box with 24 pills – between R $ 25 and R $ 34.

* Prices consulted in August 2020. Prices may change.


Generic drugs are those that have the same active ingredient as the reference, but do not have a commercial name. Thus, the name of the remedy is composed of the name of the drug and the manufacturer’s laboratory.

It may also present some change in the form of use and time of action. Another highlight is that these drugs usually have a lower price *.

Check out some generics of mefenamic acid:

  • Mefenamic Acid Medley – the box with 24 pills is between R $ 7 and R $ 20;
  • Mefenamic Acid EMS – the box with 24 pills is between R $ 7 and R $ 18;
  • Aché Mefenamic Acid – the box with 24 pills is between R $ 7 and R $ 20.

* Prices consulted in August 2020. Prices may change.


The similar drug has the same active ingredient as the reference, in addition to the same concentration, pharmaceutical form, route of administration, dosage and therapeutic indication.

However, there may be variation in the size and shape of the product, as well as factors such as the expiration date, packaging, labeling, excipients and vehicle. Unlike the generic, these remedies have a commercial name.

As an example of a similar to mefenamic acid, we can mention Standor (from União Química) – the price * of the box with 24 pills is close to R $ 22 .

* Prices consulted in August 2020. Prices may change.

Similar interchangeable

As mentioned, the interchangeable similar is considered the remedy closest to the reference. Its approval by ANVISA certifies the safe replacement of one by the other, without any changes – as long as it is aligned with the doctor and pharmacist previously.

See, in the case of mefenamic acid, the interchangeable similars and their price range *:

  • Ponsdril (box with 24 pills) – the value is close to R $ 20;
  • Pontin (box of 24 pills) – the value is close to R $ 20.