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Mefenamic Acid

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Mefenamic Acid is a painkilling medication used to treat period pain in women. It works by stopping contractions of the muscles in the wall of the uterus, alleviating period pain.
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What are Mefenamic Acid 250mg capsules?

Mefenamic Acid 250mg (brand name Ponstan) is a prescription medication available in the UK. Mefenamic acid tablets are used to treat symptoms of period pain. This medication belongs to a group of drugs called NSAIDs (non-steroidal anti-inflammatory drugs).

Mefenamic acid 250mg tablets works by reducing inflammation and is a pain killer. Mefenamic acid is a drug used to treat period pain that does not respond to painkillers such as aspirin, Ibuprofen or lifestyle changes.

How does Mefenamic Acid work?

Mefenamic acid works by reducing the production of prostaglandins. Prostaglamdins is a chemical released during a period. Prostaglandins cause period pains by causing increased contractions in the uterus. Reducing prostaglandins, mefenamic acid stops contractions of the muscles in the uterus wall. alleviating period pains. 

How to take Mefenamic Acid?

Take TWO 250mg tablets THREE times a day. For up to a maximum of THREE days during any one single menstrual cycle at the onset of period pain or bleeding, whichever is earlier.

It should be taken with or after food, and swallowed whole with water.

If you find mefenamic acid is not effective enough to control your pain, we recommend speaking to your GP for advice.

Special Instructions For Taking Mefenamic Acid tablets


Mefenamic acid can be used to treat those who suffer from Period Pain, but it is important to check if the medication is suitable for you.

It is important you take the free medical questionnaire to ensure that it is suitable for you to take.

Long-term use of Mefenamic Acid is not recommended as it can increase the risk of side effects.

You can learn more about treating premenstrual syndrome in this information from The National Association for Premenstrual Syndrome.

Ibuprofen or other NSAIDs

You should NOT take Ibuprofen or any other NSAIDs at the same time as Mefenamic Acid. You should always read the patient information leaflet (PIL)for mefenamic acid before taking this medication to ensure it is safe for you to use.

If you get diarrhoea while taking this medicine you should stop taking it and consult your doctor. Your doctor may decide that you should not take this medicine again.

Side Effects of Mefenamic Acid tablets

Please ensure you carefully read the Patient Information Leaflet accompanied with mefenamic acid tablets to read the full list of side effects. Like all medication, there is some risk of side effects such as;

  • stomach pain
  • nausea
  • vomiting
  • heartburn
  • constipation, diarrhoea, rash and dizziness

Patient information leaflet

We strongly advise that you carefully read the Patient Information Leaflet before you take this treatment.

Click here for the Mefenamic Acid Patient Information Leaflet.

Frequently Asked Questions

What is Mefenamic Acid?

Mefenamic acid is a member of a group of drugs called NSAID drugs. Mefenamic acid tablets are used to treat mild to moderate pain, including menstrual pain. Mefenamic acid 250mg tablets are also used to prevent migraines associated with menstruation. Anti-inflammatory painkillers, like mefenamic acid are also called non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs are sometimes called 'anti-inflammatories'. Mefenamic acid is a medicine that can come in tablets or tablets form.

What is Mefenamic Acid used for?

Mefenamic acid is used to treat a range of moderate pain and menstrual period pain. Some evidence suggest that mefenamic acid can be used for migraines associated with the menstrual period. This is to prevent the onset of headaches associated with menses.

Other mefenamic acid uses

Mefenamic acid is a pain reliever medication that can be used for the following conditions. Only when advised by a doctor:

  • Non-Radiographic axial spondyloarthritis medications
  • Joint Inflammatory Disease in Children and Young Adults
  • Headache caused by Disorder of Cranial Blood Vessels
  • Gout

Mefenamic acid can only be used in the above mentioned conditions only when recommended by a specialist. Mefenamic should not be used for any other type of pain unless directed by your doctor.

Mefenamic acid mechanism of action

Mefenamic acid has anti-inflammatory, analgesic and antipyretic properties. Mefenamic acid works in a similar way to other NSAIDs. Mefenamic acid works by inhibiting prostaglandin synthetase.

Mefenamic acid binds to COX-1 and COX-2 receptors. COX receptors play a major role in mediating the inflammatory response. Prostaglandins signal activity for inflammation. Mefenamic acid reduces the cramps caused by the uterine contractions.

Mefenamic acid works to relieve period cramps and pains as a result. Ponstan contains the active ingredient mefenamic acid, and exhibits these anti-inflammatory properties.

What is the best dosage for Mefenamic Acid 250mg (Ponstan) tablets?

You should always take mefenamic acid (ponstan) tablets as directed by your doctor. The mefenamic acid dosage may vary with age and with condition. The dosage for menstrual period pain in women over 18 years of age the dosage is two 250mg tablets taken three times a day. This is roughly every 8 hours for period pain relief.

How long does it take for mefenamic acid to work?

Following oral administration, mefenamic acid is rapidly absorbed in the body. Peak absorption occurs at approximately 2 to 4 hours.

Mefenamic Acid side effects

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

  • stomach pain
  • nausea
  • vomiting
  • heartburn
  • constipation
  • diarrhea
  • dizziness

Side effects of mefenamic acid are usually mild. More serious mefenamic acid side effects include:

  • diarrhea
  • hematemesis (vomiting blood)
  • hematuria (blood in the urine)
  • blurred vision, headaches
  • nervousness
  • rash, itching and swelling, sore throat and fever

Rarely it has been associated with acute liver damage.

If you experience serious or rare mefenamic acid adverse effects, contact your doctor. You must seek medical attention immediately.

Can you overdose on Mefenamic Acid?

Yes you can overdose on mefenamic acid.

Mefenamic acid overdose symptoms include:

  • nausea
  • vomiting
  • stomach pain
  • dizziness, drowsiness
  • black or bloody stools

You may also experience blood in your cough, shallow breathing. Mefenamic acid overdose can also cause fainting or coma. In case of mefenamic overdose you should contact your local emergency healthcare services.


Can you take Mefenamic Acid for headache?

You cannot usually take mefenamic acid tablets for a headache, unless you are prescribed it by your doctor. Mefenamic acid tablets are sometimes taken to relieve headaches associated with period pains.

Mefenamic Acid and Alcohol

Mefenamic acid and alcohol may increase the risks of your stomach bleeding. You should avoid drinking alcohol while you are taking mefenamic acid. If you experience bleeding caused by mefenamic acid you should seek medical attention.

Can I take mefenamic acid with other medicines?

Before taking mefenamic acid tablets you should always consult your doctor or pharmacist. You should avoid taking aspirin, ibuprofen or other NSAIDs whilst taking mefenamic acid.

Mefenamic acid in pregnancy

Pain relief treatment in pregnancy is usually not recommended. Paracetamol has established safety during pregnancy. Mefenamic acid is not usually recommended to control pain in pregnancy. Always seek the advice of your doctor before starting any medication whilst you are pregnant.

Is mefenamic acid safe for pregnant women?

It is not recommended for pregnant women to take mefenamic acid during pregnancy. Particularly in the 3rd trimester as this may cause harm to your unborn baby.

What are the indications of mefenamic acid?

Mefenamic acid tablets are usually used for the short term treatment of mild to moderate primary dysmenorrhea. Mefenamic acid helps to reduce cramping and decreases blood loss.

Mefenamic acid contraindication

Mefenamic acid is contraindicated in people who have or suffer from any of the following:

  • People who smoke
  • High blood pressure
  • Stroke or cardiovascular disease including chronic heart failure
  • Hypersensitivity
  • Stomach ulcer
  • Kidney disease
  • Pregnancy
  • Liver problems
  • Blood clots
  • Bleeding of the stomach or intestines
  • Increased risk of bleeding
  • Taking other NSAIDS e.g aspirin
  • Hypersensitive or allergic to mefenamic acid

How mefenamic acid is acid taken?

Mefenamic acid is taken by taking two tablets three times a day, for the relief of period pains and cramps.

Mefenamic acid ingredients

You should always read the patient information leaflet you receive with your mefenamic acid tablets. Different brands or manufacturers may have different ingredients. Please refer to the PIL for a full list of ingredients.

Is mefenamic acid a pain reliever?

Mefenamic acid is an analgesic, belonging to the group of anti-inflammatory drugs (NSAIDs). It is a pain reliever and is usually used for menstrual pain and cramping.

Mefenamic acid and paracetamol

You can take mefenamic acid and paracetamol at the same time. There are no known interactions.

Can you use mefenamic acid for headache?

You can only take mefenamic acid for a headache if it is associated with your menstrual pain. Do not take mefenamic acid tablets for general headaches unless directed by your doctor.

Can you buy Mefenamic acid tablets online?

You can buy Mefenamic acid tablets online, make sure you check that the website you are buying the Mefenamic acid tablets from. You can check if a pharmacy is regulated by visiting the GPhC website (General Pharmaceutical Council of Great Britain).

Avoid buying medicines from oversees online pharmacies, they could be supplying counterfeit medication. Counterfeit medication which may cause serious harm to your health.

Is it safe to buy Mefenamic acid tablets online?

It is safe to buy Mefenamic acid 250mg tablets online if the website you are buying from is registered with the GPhC. Check for the Pharmacy logo and GPhC register to ensure you are buying from a genuine pharmacy.

Can I buy Mefenamic acid OTC (over the counter)?

You cannot you buy Mefenamic acid over the counter (otc). You need a prescription for Mefenamic acid. However you can buy it online after completing an online medical questionnaire. Here at instant e-Care we provide free consultation and free prescriptions if you are eligible for treatment.

More Information
Dosage Instructions Take ONE tablet up to THREE times a day when required.