Mefenamic Acid

Available in a 28, 84 and a 100 pack

  • Mefenamic acid can relieve period pain as well as headaches, toothache and muscular pain.
  • Can also reduce excessive menstrual bleeding. 
  • Non-steroidal anti-inflammatory drug (NSAID).
  • Always read the patient information leaflet before use. 
28 Tablets
84 Tablets
The treatment is inclusive of consultation, private prescription & medicine delivery
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Faye Bonnell - Medical Content Writer
Faye Bonnell
Medical Content Writer
James O'Loan - CEO & Superintendent Pharmacist
James O'Loan
CEO & Superintendent Pharmacist

Buy Mefenamic Acid

Mefenamic acid is a non-steroidal anti-inflammatory drug (NSAID) that can relieve pain, swelling and fever. This medicine is used to relieve period pain, as well as headaches, toothache, muscular pain, pain after an operation or giving birth, and pain or stiffness related to rheumatoid arthritis and osteoarthritis. Mefenamic acid can also reduce excessive menstrual bleeding.

How does mefenamic acid relieve period pain?

There are hormones called prostaglandins in the lining of the uterus that can be the cause of period pain and heavy periods. Mefenamic acid works to relieve period pain and excessive bleeding by reducing these hormones. Being a non-steroidal anti-inflammatory drug (NSAID), mefenamic acid also reduces inflammation and fever.



Adults aged 18 and over should usually take three 500mg tablets, three times a day. If you’re taking mefenamic acid tablets for period pain, you should start taking the tablets when the pain begins. If you’re taking this medication to reduce excessive menstrual bleeding, you should take it on the first day of the excessive bleeding.

If you’re over 65, your doctor or Chemist4U pharmacist may offer a lower dose. You may also need to be monitored for stomach bleeding at the beginning of your treatment.


Side Effects

As with all medicines, mefenamic acid can cause side effects, but not everyone gets them. If you experience any symptoms of the following rare but severe side effects, stop taking mefenamic acid and seek medical attention immediately: 

  • Allergic reaction: wheezing, difficulty breathing, feeling faint, swelling of the face or tongue, swelling of the hands and feet or intense itchy skin rash. 
  • Serious illness with blistering of the skin, mouth, eyes and genitals.
  • Blood in your stools, loose stools or black tarry stools 
  • Vomiting blood or dark particles that look like coffee grounds

You should stop taking these tablets and tell your doctor if you experience heartburn, indigestion, stomach pain or other abnormal stomach symptoms.

For more information about possible side effects, refer to the patient information leaflet. If you experience any side effects, including any not included in the patient information leaflet, you can report them using the MHRA Yellow Card Scheme



These mefenamic acid tablets may not be suitable for everyone. You must not take this medication if: 

  • You are allergic to Mefenamic Acid, any of the other ingredients in this medicine, or other NSAIDs
  • You are taking aspirin or any other NSAIDs, including cyclo-oxygenase-2-specific inhibitors
  • You have severe liver or kidney problems
  • You have severe heart failure, which can cause shortness of breath or ankle swelling.
  • You are in the final 3 months of pregnancy
  • You have or have ever had peptic ulceration (ulcer in your stomach or intestine)
  • You have ever had bleeding in your digestive tract when you have taken NSAIDs in the past
  • You have inflammation of your bowels

You must not use these mefenamic acid tablets to treat pain after a heart bypass surgery. You should talk to a doctor or Chemist4U pharmacist before taking Mefenamic Acid if:

  • You are elderly
  • You are suffering from or have a history of bronchial asthma
  • You suffer from high blood pressure
  • You have heart failure or any other heart or vascular problems
  • You have mild kidney problems
  • You suffer from ulcerative colitis or Crohn’s disease
  • You suffer from systemic lupus erythematosus (inflammation of the connective tissue) or mixed connective tissue disease
  • You suffer from epilepsy
  • You are elderly and suffering from dehydration or kidney problems
  • You are taking any other medicines or herbal remedies, including those obtained without a prescription

Pregnancy and Breastfeeding Warning

You should always ask your doctor or Chemist4U pharmacist about taking any medicines if you are pregnant, think you may be pregnant, or are trying to become pregnant. You must not take mefenamic acid during the final 3 months of your pregnancy or if you are breastfeeding. Mefenamic acid may also make it more difficult for you to become pregnant.

Age Restrictions

Mefenamic acid 500mg tablets are not suitable for use in children and adolescents under 18. There are alternative forms of mefenamic acid that may be more suitable.


Keep this medicine out of the sight and reach of children and store below 25°C in a cool, dry place away from direct sunlight. Do not use this medicine after the expiry date, which is stated on the packaging. The expiry date refers to the last day of that month.

Important information

This product is a medicine; make sure to speak to your doctor or Chemist4U pharmacist before taking this product if you have an underlying medical problem or are taking any other medicine or complementary therapy. If your symptoms get worse or continue after taking this product, contact us or your doctor. For medical services in your area, please refer to

If you are pregnant, trying to become pregnant, or breastfeeding, speak to your doctor or our pharmacist before taking this product. If you suffer from any allergies, ask your doctor or our pharmacist if this medicine is right for you.

Store all medicines out of sight and reach of children.

Please read the included leaflet carefully before using this product.

Please contact your GP if appropriate regarding this product.

Helpful Advice on Medication Restrictions & Addiction

For further information on our medication restrictions policy, please click here.

If you are concerned about addiction to 'over the counter' medication, we urge you to visit the below links for professional help and advice:

NHS Help & Advice on Drug Addiction

Talk To Frank - Drug Addiction Help & Support



What causes period pain?

Period pain is extremely common, affecting most women at some point in their lives. It can be extremely painful, with intense spasms in the stomach and pain that can spread to the back and thighs.

During a period, the muscular wall of the womb starts to contract so the lining can shed. When this contraction happens, blood vessels in the lining of the womb are compressed and the blood supply to the womb is temporarily cut off. When there’s no blood supply, there’s no oxygen, and this causes the tissues in the womb to release chemicals that trigger pain. When those chemicals are released, hormones called prostaglandins encourage the muscles in the womb to contract even more and the pain further intensifies.

Sometimes, certain medical conditions can make your periods more heavy and painful. These include endometriosis, fibroids, pelvic inflammatory disease or adenomyosis.

Do I need a prescription for mefenamic acid?

You do need a prescription for mefenamic acid in the UK. Our healthcare professionals can provide prescriptions if they think this treatment would be right for you and your condition. When you click the button which reads “Start Consultation” at the top of this page, you’ll see a short questionnaire set up by our healthcare team which is designed to help them understand your medical needs. Just like an in-person consultation with your GP, our doctors will assess your answers to their questions and write a prescription for the treatment they think will be best for you. You’ll then be able to pay for your medication and we’ll send it out to you quickly and in discreet packaging.

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