• Specifically effective for period pain relief
  • Blocks pain and inflammation at the source
  • Also treats muscle, back and dental pain

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Overview

Mefenamic acid is a proven prescription painkiller that’s often used for period cramps, easing the abdominal and back pain that so often disrupt your day. By targeting the cause of pain and inflammation, it provides fast, reliable relief - not just for menstrual pain, but also for muscle aches, back pain, and dental pain.

 

What is Mefenamic acid

Mefenamic acid is a prescription-only non-steroidal anti-inflammatory drug (NSAID) that works by blocking the body’s production of prostaglandins - natural chemicals that trigger pain, inflammation, and muscle contractions. By reducing these chemicals, mefenamic acid provides effective relief from moderate pain and discomfort.

It is especially effective for period pain (dysmenorrhoea), where it helps ease abdominal cramps, back pain, and pelvic discomfort caused by uterine contractions. Unlike standard painkillers, mefenamic acid doesn’t just dull the pain - it actively reduces the inflammation that causes it, helping you feel more comfortable and in control throughout your cycle.

In addition to menstrual pain, mefenamic acid can also be prescribed for muscle aches, back pain, dental pain, and mild arthritis-related discomfort, offering flexible, targeted relief when ordinary painkillers aren’t enough.

Because it tackles both pain and inflammation, many people find it not only relieves discomfort but also helps restore energy and movement - allowing them to get back to their day with minimal disruption.

Directions

  • Usual adult dose: 500mg initially, followed by 250mg every 6 hours as required.
  • Take with food or milk to reduce stomach irritation.
  • Do not exceed the maximum daily dose recommended by your prescriber.
  • Use the lowest effective dose for the shortest possible time.

Side Effects

Mefenamic acid is generally well tolerated, but side effects may occur.

Common (may affect up to 1 in 10 people):

  • Indigestion or stomach pain
  • Nausea or diarrhoea
  • Heartburn


Uncommon (may affect up to 1 in 100 people):

  • Headache or dizziness
  • Constipation or bloating
  • Rash or itching


Rare but serious (seek urgent help):

  • Severe stomach pain, vomiting blood, or black stools (signs of bleeding)
  • Chest pain or shortness of breath (possible heart-related side effects)
  • Severe allergic reaction (swelling, rash, difficulty breathing)


Disclaimer: This is not a complete list of side effects. Always read the patient information leaflet that comes with your medicine for full details. If you notice anything unusual or concerning, stop taking mefenamic acid and seek medical advice promptly. In an emergency, call 999 or go to A&E.

Warnings

  • Not suitable if you have a history of stomach ulcers, bleeding disorders, severe kidney or liver problems, or certain heart conditions.
  • Avoid if allergic to mefenamic acid, aspirin, or other NSAIDs.
  • Not recommended in late pregnancy.
  • Use with caution if taking blood thinners, corticosteroids, SSRIs, or other NSAIDs.
  • Limit alcohol while taking to reduce risk of stomach irritation.
Frequently asked questions

  • What is mefenamic acid 500 mg and how does it work?

    Mefenamic acid 500 mg is a higher-strength anti-inflammatory tablet used for short-term pain relief. It works by reducing inflammatory chemicals that cause swelling and cramping, making it particularly useful for painful periods or musculoskeletal discomfort.

  • What is mefenamic acid 500 mg used for?

    The mefenamic acid 500 mg strength is typically prescribed for more intense period pain, pelvic cramping, injury-related pain or post-operative discomfort. Its higher dose provides stronger anti-inflammatory action when standard doses may not be enough.

  • How should I take mefenamic acid 500 mg tablets?

    Take one 500 mg tablet up to three times daily with food. Swallow it whole and avoid taking more than prescribed. Do not combine with other anti-inflammatories unless advised, as this increases the risk of stomach irritation.

  • How long does mefenamic acid 500 mg take to work?

    Many people feel relief within one hour, with continued improvement over the next few hours as inflammation reduces. Taking the first dose at the start of symptoms usually gives the best results for menstrual or cramping pain.

  • What side effects should I expect?

    Common effects include indigestion, nausea, diarrhoea or headache. Stomach discomfort is more likely with higher strengths, so always take it with food.Seek urgent care if you experience vomiting blood, black stools or severe abdominal pain.

  • Who should not take mefenamic acid 500 mg?

    Avoid it if you have stomach ulcers, inflammatory bowel disease, severe heart, liver or kidney problems, or if you are in late pregnancy. People taking blood thinners or lithium should also check with a clinician first.

  • Can I combine mefenamic acid 500 mg with other painkillers?

    Yes, it can be taken with paracetamol. Avoid combining it with ibuprofen, naproxen or aspirin unless advised, as using multiple anti-inflammatories increases stomach and kidney risks.

  • Why would a clinician prescribe the 500 mg strength instead of the 250 mg capsules?

    The mefenamic acid 500 mg tablet provides a stronger anti-inflammatory effect, making it helpful for people whose symptoms do not respond well to lower doses. It may also reduce the number of tablets needed each day, which some patients find more convenient.

  • Is mefenamic acid 500 mg better for severe menstrual pain?

    Yes. Higher-strength anti-inflammatories can provide more effective relief when period pain is intense or when cramps are linked to heavy bleeding. Starting treatment at the first sign of discomfort usually improves results.

  • Can I split a 500 mg tablet if the dose feels too strong?

    No. These tablets are not designed to be split, and doing so may affect how the medicine is absorbed. If the dose feels too strong, speak to a clinician about switching to 250 mg capsules instead.

  • Is it safe to use 500 mg tablets for several days each month?

    Many people use them safely for short periods each month, especially for menstrual pain. However, higher doses carry a slightly greater risk of stomach irritation, so regular reviews are recommended if use becomes frequent.

  • Can mefenamic acid 500 mg trigger migraines or headaches?

    Headaches can occur, especially at higher doses, although this is uncommon. If headaches worsen or feel like migraines, stop the tablets and seek advice, as an alternative anti-inflammatory may suit you better.

  • Should I avoid certain foods or drinks while taking the 500 mg dose?

    You should avoid alcohol, as it increases the risk of stomach irritation with higher-strength anti-inflammatories. Spicy or acidic foods can also worsen indigestion in some people. Taking mefenamic acid with a substantial meal usually improves comfort.

  • What should I do if the 500 mg dose causes stomach discomfort?

    Try taking the tablet with a larger meal, milk or a protective stomach medicine if advised. If discomfort continues, a lower strength or alternative painkiller may be safer. Persistent symptoms should be assessed by a clinician.

  • Can I buy mefenamic acid 500 mg tablets online safely?

    Yes. UK-registered pharmacies can supply them after confirming they are safe for you, particularly checking your stomach history and any other anti-inflammatory medicines.