Mefenamic Acid 500mg Tablets
  • Mefenamic Acid 500mg Tablets

Mefenamic Acid

Medication features

Mefenamic acid is a medication used to alleviate menstrual cramps and reduce pain during periods. It works by reducing inflammation and relieving pain associated with menstrual cycles.

  • Commonly prescribed for period pain
  • Take with food
  • Can be taken with paracetamol


Order Mefenamic Acid Tablets Online

You can buy mefenamic acid from our UK registered online doctor service. Once you have completed the online doctor consultation, it will be reviewed by our UK trained GPs and then prescribed if safe and appropriate. The prescription is then passed to our online pharmacy team, and your order is dispatched to your delivery address.

What is Mefenamic acid?

Mefenamic acid belongs to a family of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). This is part of the same family of drugs as ibuprofen and aspirin. It is used to treat pain and inflammation and treat period pain or abnormally heavy periods.

Mefenamic acid, in the UK, is a prescription-only medicine which means it must be prescribed by a doctor. The most common strength is mefenamic acid 500mg, but a lower strength of 250 mg is also available. 

How does Mefenamic acid work?

Women who have abnormally heavy or painful periods have been shown to have high levels of hormones called prostaglandins. These are known to cause cramping abdominal pain and are linked to heavy periods. NSAIDs work by stopping prostaglandins from being produced by certain enzymes. This causes prostaglandin levels in the body to drop.

Mefenamic acid side effects 

Seek medical help immediately if you notice any signs of an allergic reaction such as severe skin itching, difficulty breathing, and swelling of the face, lips or tongue. You should also seek medical help if you notice diarrhoea, blood in your stools, black stools, vomiting blood or vomit that looks like coffee grounds.

You must be aware of the possible side effects of this medicine. See section 4 of the patient information leaflet for a complete list of side effects.

Alternative treatments

There are several other treatments women with painful periods can try. This includes other NSAID medicines such as ibuprofen and naproxen. However, research suggests aspirin isn’t effective at treating period pain.

Paracetamol is a medicine that you can buy over the counter to help with painful periods. Paracetamol and mefenamic acid can be taken together if needed.

Tranexamic acid is a prescription-only medicine that can also help with painful periods and it works differently to NSAIDs. This is taken for a maximum of 4 days at the time of your period.

Other possible treatments include combined contraceptive pills, intrauterine system (IUS) and in some cases, surgery may be beneficial. See the NHS page on treatments for heavy periods for more information.

Mefenamic acid summary


Usual dose is one tablet, three times a day

How it works

Acts on hormones that cause heavy and painful periods


From £19.90


What is mefenamic acid used to treat? 

It’s used to treat period pain or abnormally heavy periods. It can also be used for other conditions such as surgical pain, arthritis pain and swelling, muscular pain, and dental pain.

Which is better, mefenamic acid or paracetamol?

Research has shown that NSAIDs, like mefenamic acid, are more effective than placebo for period pain. Research also suggests that NSAIDs appeared to be more effective for period pain relief than paracetamol. 

However, both can be taken together. Paracetamol is a common and generally safe painkiller that can be taken with mefenamic acid.

Can mefenamic acid stop periods?

Mefenamic acid is for period pain, but it does not stop periods. It can improve heavy periods and provide period pain relief and provide relief from stomach pains and cramps.

Is mefenamic acid the same as ibuprofen?

It’s a different drug to ibuprofen. However, both drugs belong to the same family of medicines, called nonsteroidal anti-inflammatory drugs (NSAIDs). These are commonly used to treat mild to moderate pain and inflammation in various conditions.

Can you buy mefenamic acid over the counter?

You cannot buy mefenamic acid in the UK over the counter. This is because it’s a prescription-only medicine and must be prescribed by a doctor or healthcare professional. However, you can request to buy mefenamic acid online from registered online pharmacies in the UK.

Our online doctor service offers mefenamic acid tablets in the UK after completing a short online assessment.


What is the best painkiller for period pain?

The best tablets for period pain will differ from person to person. Some people will find taking paracetamol or ibuprofen is effective at providing relief. Others may need to speak to their GP to get stronger painkillers like naproxen and mefenamic acid. 

What self-help measures can I try for period pain?

Gentle exercising like swimming, walking or cycling may help to reduce the pain. A warm bath, or sleeping with a hot water bottle may also help soothe period pain. Having a back and stomach massage may be useful, and relaxation techniques like yoga or pilates can also help.

If you smoke, stopping smoking may help improve the pain. It’s thought that smoking increases period pain because it may reduce the supply of oxygen to the pelvic area.


Info Leaflet

Info Leaflet

Before taking any medication, it is important to read the Patient Information Leaflet. You can find information leaflets for your medicines by typing them into the search bar at or contacting us. 

Mefenamic acid PIL


How to take Mefenamic acid

The mefenamic acid dose is one tablet up to three times a day. You should not exceed this dose because taking too much can harm your kidneys and may cause seizures. If you think you’ve taken too much, talk to your doctor, pharmacist, or nearest hospital department immediately.

See section 3 of the patient information leaflet for further information.



This medicine is not suitable for everyone to take. People who are allergic to mefenamic acid, or any of the ingredients in the tablets, should not take this medicine. It’s also not suitable for people who are allergic to other NSAID medicines like aspirin, ibuprofen or naproxen. 

People with inflammatory bowel diseases like Crohn’s disease or ulcerative colitis should not take this medicine.

A history of bleeding in the stomach, peptic ulcers, severe heart, liver or kidney disease means you should not take mefenamic acid. It’s not suitable for pregnant or breastfeeding women to take.

See section 2 of the patient information leaflet for a complete list of warnings with mefenamic acid.

Other medicines and mefenamic acid

Some medicines can interact with mefenamic acid and they should not be taken together. This includes medicines such as warfarin, aspirin, digoxin, diltiazem, methotrexate, lithium and diuretics. For information on all medicines that interact with mefenamic acid, see the patient information leaflet or ask your pharmacist for advice.

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Mefenamic Acid

Medication Simple Online Pharmacy
500mg xMefenamic Acid 500mg Tablets x 28 £19.90
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