Also called Mefenamic acid

Key points about Ponstan

  • Ponstan is an anti-inflammatory used to treat pain and inflammation, especially period pain.
  • Ponstan is also called mefenamic acid.
  • Find out how to take it safely and possible side effects.
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Ponstan is in a group of medicines known as non-steroidal anti-inflammatory drugs (NSAIDs). It's used to treat different types of pain especially painful periods (menstruation), and heavy bleeding in periods.

Ponstan works by reducing hormones called prostaglandins in the lining of your uterus (womb). These hormones can cause heavy periods and period pain. Ponstan helps to ease period pain and reduce heavy bleeding from periods, but does not reduce the number of days the period lasts.

Ponstan also provides short term relief of dental pain and pain associated with muscle and joint injuries such as sprains, strains and tendonitis.

In New Zealand Ponstan is available as capsules.

  • The usual dose of Ponstan is 500 mg 3 times a day.
  • If you are using Ponstan for painful periods, take your first dose as soon as your period starts or pain begins, until the pain eases. If you are taking it for heavy bleeding, take it for no more than 7 days.
  • Always take Ponstan exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it and any special instructions.

  • Take Ponstan with food or immediately after food, to prevent stomach upset. 
  • Take your dose with a full glass of water.
  • Swallow the capsules whole — don't crush or chew them.
  • Avoid or limit alcohol while you are taking Ponstan. Alcohol can increase the risk of stomach side effects.
  • It's not harmful if you miss your Ponstan dose. If you miss a dose, take it when you remember, with or after food. Don't take double the dose.

For most people taking Ponstan is safe, but extra care is needed in some situations. For example if:

  • you have high blood pressure
  • you have heart or kidney problems or asthma
  • you're aged 65 years or older
  • you smoke.

It can also be harmful if you take Ponstan when you are dehydrated or have been sick with diarrhoea (runny poos) or vomiting (being sick). Read more about the risks of NSAIDs.

When you should NOT take Ponstan

Ponstan should NOT be used in some situations as it can be harmful. For example, if you:

  • have current or previous stomach problems such as ulcers or bleeding
  • are pregnant
  • have heart failure or chest pain (angina)
  • have had a stroke or heart attack
  • have chronic kidney disease
  • have had an allergic reaction (such as hives or trouble breathing) to ibuprofen, aspirin, or other similar medications (discuss with your healthcare provider)
  • are taking medicines to reduce blood clots (anticoagulants) such as warfarin, dabigatran or rivaroxaban
  • are also taking other anti-inflammatory medicines, eg, ibuprofen, diclofenac (Volatren), naproxen (Naprosyn®) or celecoxib (Celebrex)
  • are taking some blood pressure medicines such as ACE inhibitors, ARBs, diuretics. Always check with your healthcare provider before taking NSAIDs.

Read more about the risks associated with NSAIDs

Don't take other anti-inflammatory medicines such as ibuprofen, diclofenac, naproxen or celecoxib while taking Ponstan.

It's safe to take Ponstan with paracetamol because they work differently.

Ponstan interacts with some medicines, especially those used for high blood pressure, so check with your doctor or pharmacist before you start taking Ponstan.

Image credit: University of Otago

Taking NSAIDs together with blood pressure medicines can be harmful to your kidneys. This is called the ‘triple whammy’. If you are taking blood pressure medicines (ACE inhibitors or ARBs and diuretics) tell your doctor or pharmacist before starting Ponstan.

  • Examples of ACE inhibitors are captopril, cilazapril, enalapril, lisinopril, perindopril and quinapril.
  • Examples of ARBs are candesartan, irbesartan and losartan.
  • Examples of diuretics are furosemide, bumetanide, bendroflumethiazide, chlortalidone, indapamide, spironolactone, eplerenone and metolazone.

Read more about the triple whammy.(external link) 

Like all medicines, Ponstan can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine. 

Side effects What should I do?
  • Heartburn
  • Indigestion
  • Stomach discomfort
  • Runny poo (diarrhoea)
  • These are common and should settle within a few days.
  • Take Ponstan with food.
  • Talk to your doctor if they're ongoing.
  • Serious stomach problems such as really bad stomach pain, blood in your stool or black stools, cough or vomiting up blood or dark-coloured vomit.
  • Stop taking Ponstan.
  • Tell your doctor immediately or ring Healthline on 0800 611 116.
  • Chest pain
  • Shortness of breath or trouble breathing
  • Weakness in one part or side of your body
  • Slurred speech
  • Stop taking Ponstan.
  • Tell your doctor immediately or ring Healthline on 0800 611 116.
  • Swollen ankles, blood in your pee or not peeing at all – these can be signs of a kidney problem.
  • Stop taking Ponstan.
  • Tell your doctor immediately or ring Healthline on 0800 611 116.
  • Signs of an allergic reaction such as skin rash, itching, swelling of your lips, face and mouth or difficulty breathing
  • Stop taking Ponstan.
  • Tell your doctor immediately or ring Healthline on 0800 611 116.
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product.(external link)

The following links provide further information about mefenamic acid. Be aware that websites from other countries may have information that differs from New Zealand recommendations.

Ponstan(external link) Medsafe Consumer Information Sheets, NZ
Mefenamic acid for pain and inflammation (Ponstan)(external link) Patient info, UK


5 questions to ask about your medications(external link) Health Quality and Safety Commission, NZ, 2019 English(external link), te reo Māori(external link)


  1. Mefenamic acid(external link) NZ Formularly
  2. Ponstan(external link) NZ data sheet

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Auckland

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