Mefenamic Acid 500 mg film-coated tablets – patient leaflet, side effects, dosage

1. What Mefenamic Acid is and what it is used for

Mefenamic Acid Film-Coated Tablets contain mefenamic acid which is a non-steroidal anti-inflammatory drug (NSAID).

They can help to relieve:

• symptoms of inflammation, such as redness

  and swelling

• pain and discomfort caused by arthritis,

  muscular or rheumatic disorders

• headache, muscle ache or toothache
• pain after operations, trauma
• childbirth pain
• fever in children
• painful or heavy periods.

2. What you need to know before you take Mefenamic Acid

Do not take Mefenamic Acid if you:

• are allergic to mefenamic acid, to any other

  anti-inflammatory medicines (such as aspirin, ibuprofen, celecoxib), or any of the other ingredients of this medicine (listed in section 6)

• have, or have ever had, stomach or intestinal

  conditions such as peptic ulcer, bleeding in the stomach or severe gastritis

• have an inflammatory bowel disease (e.g. ulcerative colitis, Crohn's disease)
• have severe heart, liver or kidney problems
• have just had heart bypass surgery
• are more than 6 months pregnant.

If any of the above apply to you, speak to your doctor or pharmacist.

Warnings and precautions

Talk to your doctor or pharmacist before taking Mefenamic Acid if you:

• are taking any other NSAIDs (e.g. ibuprofen,

  diclofenac)

• are taking any other anti-inflammatory

  medicines including steroids (e.g. prednisolone)

• are taking aspirin or medicines that thin the

  blood (e.g. warfarin, clopidogrel)

• are taking antidepressants called selective

  serotonin re-uptake inhibitors (SSRIs) (e.g. paroxetine)

• have kidney or liver problems. Your doctor may

  check your kidney or liver function before and during treatment

• are elderly (see section 3)

• are trying to become pregnant (see section on

  Fertility)

• have stomach or digestive tract problems or if you

  ever had an upset stomach after taking pain killers such as aspirin. Bleeding in the stomach or gut can occur in patients taking Mefenamic Acid

• have a bleeding disorder or if you are going to

  have a major operation. Mefenamic Acid can affect the clotting of your blood. It can make you bleed more and for longer than usual

• have asthma, or a history of asthma, as this

  medicine may cause breathing difficulties

• have a connective tissue disorder, e.g.

  Systemic Lupus Erythematosus (SLE)

• have epilepsy

• are dehydrated (thirsty with dry skin, dark urine,

  dry mouth, headache)

• have heart problems, previous stroke or think

  that you might be at risk of these conditions (e.g. if you have high blood pressure, diabetes or high cholesterol or are a smoker). Additional monitoring may be carried out by your doctor. Medicines such as Mefenamic Acid may be associated with a small increased risk of heart attack or stroke. Any risk is more likely with high doses and prolonged treatment. Do not exceed the recommended dose or duration of treatment. Blood tests

Your doctor may test your blood during treatment. Other medicines and Mefenamic Acid

Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines.

Some medicines may be affected by Mefenamic Acid or they may affect how well Mefenamic Acid will work. Tell your doctor or pharmacist if you are taking:

• medicines that can increase the chance of getting

  ulcers or a bleed in the stomach or gut, such as:

  • corticosteroids used to treat arthritis and

    inflammation

  • medicines such as anti-platelet agents, used

    to thin the blood (e.g. warfarin, aspirin, clopidogrel)

  • antidepressants called selective serotonin

    re-uptake inhibitors (SSRIs) (e.g. paroxetine)

  • any other anti-inflammatory medicines (e.g.

    diclofenac, celecoxib)

• aspirin including low doses of aspirin used to

  prevent your blood from clotting in certain heart conditions

• medicines used for high blood pressure (e.g.

  atenolol, ramipril, valsartan)

• diuretics (water tablets) or heart medicines (e.g.

  digoxin, sotalol, diltiazem)

• some diabetic medicines (e.g. glipizide,

  glibenclamide)

• medicines which suppress the immune system

  (e.g. ciclosporin, tacrolimus, methotrexate)

• lithium, a medicine used to treat mood swings

  and some types of depression

• a medicine usually prescribed through hospitals,

  called mifepristone (taken within the last 12 days)

• quinolone antibiotics (antibiotics used to treat

  infections)

• aminoglycoside antibiotics, used under medical

  supervision in hospitals

• zidovudine, a medicine used for HIV

• probenecid, a medicine used in special cases,

  to protect the kidneys

• medicines which bind to protein in the blood -

  (check with your pharmacist).

Mefenamic Acid with alcohol

Avoid drinking alcohol. It may increase your risk of stomach bleeding.

Pregnancy, breast-feeding and fertility

If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor for advice before taking this medicine. Pregnancy

Mefenamic Acid will be passed to your unborn baby. You should not take Mefenamic Acid during the first 6 months of pregnancy unless absolutely necessary and advised by your doctor. If you need treatment during this period or while you are trying to get pregnant, the lowest dose for the shortest time possible should be used. If taken for more than a few days from 20 weeks of pregnancy onward, Mefenamic Acid can cause kidney problems in your unborn baby that may lead to low levels of amniotic fluid that surrounds the baby (oligohydramnios) or narrowing of a blood vessel (ductus arteriosus) in the heart of the baby. If you need treatment for longer than a few days, your doctor may recommend additional monitoring.

DO NOT take the film-coated Tablets in the last 3 months of pregnancy as they may harm your unborn child and cause problems at delivery. They can cause kidney and heart problems in your unborn baby. They may affect your and your baby's tendency to bleed and cause labour to be later or longer than expected. Breast-feeding

Mefenamic Acid passes into breast milk and can affect the baby. You should not take the film-coated Tablet while breast-feeding unless advised by your doctor. Fertility

DO NOT take the film-coated tablet if you are trying to become pregnant, as they may make it more difficult to get pregnant. You should inform your doctor if you are planning to become pregnant or if you have problems becoming pregnant.

Driving and using machines

Mefenamic Acid may cause drowsiness, dizziness, fatigue or affect your vision. If any of these occur do not drive, use machinery, or perform any tasks that may require you to be alert.

Mefenamic Acid Film-Coated Tablets contain lactose

If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicine.

This medicine contains less than 1 mmol sodium (23 mg) per film-coated tablet, that is to say essentially ‘sodium-free’.

3. How to take Mefenamic Acid

Always take this medicine exactly as your doctor or pharmacist has told you. Your doctor will decide on the appropriate dose to suit your condition. Check with your doctor or pharmacist if you are not sure.

• Take the film-coated tablet with or immediately

  after a meal.

• Do NOT drink alcohol while taking Mefenamic

  Acid. Alcohol and smoking can irritate the stomach and make some of the side effects worse.

  Dosage

  Adults

  For Mefenamic Acid 250 mg Film-Coated Tablet: The recommended dose is 2 film-coated tablets three times a day.

  For Mefenamic Acid 500 mg Film-Coated Tablet: The recommended dose is 1 film-coated tablet three times a day.

  Elderly patients (over 65 years)

  Elderly patients are at a higher risk of side effects and should take the lowest effective dose for the shortest possible time, with additional monitoring carried out by their doctor.

  Use in children

  It is recommended that children under 12 years of age should be given Mefenamic Acid Suspension (50 mg / 5 ml).

  If you take more Mefenamic Acid than you should

  If you take more film-coated tablets than you should you may harm your stomach, kidneys and you may get seizures (fits). Symptoms of overdose may also include headache, abdominal pain (pain in your stomach) or other abnormal stomach symptoms, nausea (feeling sick), vomiting, rarely diarrhoea, disorientation, excitation, coma (loss of

  consciousness for a period of time), tiredness, ringing in the ears and fainting.

  1. 1.

     Tell your doctor, pharmacist or nearest hospital

     casualty department immediately.

  2. 2.

     Take the container and any remaining

     film-coated tablets with you so that people can see what you have taken.

  3. 3. Do this even if you feel well.

If you forget to take Mefenamic Acid

If you forget to take a dose take it as soon as you remember, but if it is almost time for your next dose, skip the missed dose and continue as usual. Do not take a double dose to make up for a forgotten dose.

If you have any further questions on the use of this medicine, ask your doctor or pharmacist.

4. Possible side effects

Like all medicines, this medicine can cause side effects, although not everybody gets them. Do not be alarmed by this list of possible side effects. You may not experience any of them.

STOP taking the film-coated tablets and seek medical help immediately if you have any of the following allergic reactions:

• difficulty breathing or swallowing, swelling of the

  face, lips, tongue or throat

• severe itching of the skin, with a red rash or

  raised lumps

• blistering of the mouth, eyes, and genital region,

  and patchy areas of rash, peeling skin or any of the following reactions

• diarrhoea
• passing blood in your stools (faeces/motions)
• passing black tarry stools

• vomiting any blood or dark particles that look

  like coffee grounds.

Seek immediate medical attention if you have any of the following symptoms:

• indigestion or heartburn, abdominal pain (pain

  in your stomach) or other abnormal stomach symptoms, nausea (feeling sick), vomiting

• any unusual bruising or bleeding, for example

  nose-bleeds, pinpoint red spots on the skin, unusual purple bruise-like rash on the skin or in the mouth

• signs of anaemia such as feeling tired,

  breathless, and looking pale

• fever, sore throat, mouth ulcers, repeated

  infections or infections that will not go away. This may be due to a low level of white blood cells

• seizures (fits)

• signs of low sodium levels such as headache,

  nausea, vomiting, tiredness, muscle cramps

• sudden headache, stiff neck, fever, sensitivity to

  bright light, drowsiness and muscle pain, with or without a rash

• fever, rash, nausea, aches and pains, passing

  more or less urine than usual, passing red urine or passing urine at night. This may be due to changes in your kidneys

• sudden loss or blurring of vision, loss of colour

  vision, eye pain which worsens with eye movement

• headache, in particular on waking in the morning.

  This may be due to high blood pressure

• pain behind the ribs radiating towards the back,

  often worse when lying down, nausea, vomiting, fever. This may be due to inflammation of your pancreas

• yellowing of your skin or eyes, pale faeces and

  dark urine, unexplained persistent nausea, stomach problems, loss of appetite or unusual tiredness. This may be due to changes in your liver

• worsening of colitis and Crohn’s disease
• elevation of one or more liver function tests

• failure of various organs at the same time

  (multi-organ failure)

• heart failure.

The side effects listed below have been reported: Not known: frequency cannot be estimated from the available data

• head-spins (vertigo)

• fatty stools

  • sweating
  • rapid heartbeat (palpitations)
  • mental confusion
  • loss of appetite
  • constipation or bloating
  • blurred vision, eye irritation
  • feeling ill (malaise)
  • ringing or buzzing in the ears (tinnitus)
  • numbness or tingling in hands or feet
  • sudden poor blood sugar control if you have diabetes. Your doctor or pharmacist can measure your sugar levels
  • asthma or asthma that is worse than usual
  • swelling of your hands and feet (around the ankles)
  • sore mouth (pain or ulcers on the tongue, cheeks, lips, throat or gums)
  • dizziness, drowsiness, feeling lethargic and tired

  • signs of low blood pressure such as

    light-headedness

  • reactions to the sun. Your skin may become red, painful and swollen - do not sunbathe, use a sun bed, or expose your skin to artificial UV light
  • depression
  • inability to sleep
  • hallucinations
  • nervousness
  • ear pain.

Medicines such as Mefenamic Acid may be associated with a small increased risk of heart attack or stroke. (See section 2 - end of ‘Warnings and precautions’).

Urine tests

Tell the doctor if you are having urine tests, as your medicine may affect the results.

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.

5. How to store Mefenamic Acid

Keep this medicine out of the sight and reach of children.

Do not use this medicine after the expiry date which is stated on the blister, carton/bottle/container after EXP. The expiry date refers to the last day of that month. Store in the original package. Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.

6. Contents of the pack and other information

What Mefenamic Acid contains

• The active substance is mefenamic acid. Each film-coated tablet contains 250 mg/ 500 mg mefenamic acid.

• The other ingredients are:

  lactose monohydrate, pregelatinized starch, croscarmellose sodium, povidone,

  microcrystalline cellulose, colloidal silicon dioxide, magnesium stearate, purified water, hypromellose (E464), titanium dioxide (E171), macrogol (E1521), iron oxide yellow (E172), talc (E553b) and iron oxide red (E172).

(See end of section 2 for further information on lactose).

What Mefenamic Acid looks like and contents of the pack

For Mefenamic Acid 250 mg Film-Coated Tablets: Description:

Yellow coloured, oval shaped (about 15.10 mm x 6.30 mm), film-coated tablets plain on both sides. For Mefenamic Acid 500 mg Film-Coated Tablets: Description:

Yellow coloured, oval shaped (about 19.00 mm x 8.90 mm), film-coated tablets plain on both sides. They are available in blister packs containing 28’s and 100’s

Marketing Authorisation Holder and Manufacturer

Relonchem Limited,

Cheshire House, Gorsey Lane,

Widnes, Cheshire, WA8 0RP, UK.

Product Licence Number:

PL 20395/0413 - Mefenamic Acid 250 mg Film-Coated Tablets

PL 20395/0414 - Mefenamic Acid 500 mg Film-Coated Tablets

This leaflet was last revised in September 2025.

If you would like this leaflet in a different format, such as Braille, audio, CD-ROM or large print, please contact the license holder at the above address.