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Mefenamic Acid 500mg tablets are a prescription-strength non-steroidal anti-inflammatory drug (NSAID) used to provide effective relief from moderate pain and reduce heavy menstrual bleeding.
Order before 3pm — same-day dispatch (MON - FRI)
~5 min consultation
Secure & confidential · Reviewed by a UK prescriber
Suitable age
12 years +
Max per order
2 packs
Consultation
Yes — free online consultation required
Mefenamic Acid 500mg tablets are a prescription-strength non-steroidal anti-inflammatory drug (NSAID) used to provide effective relief from moderate pain and reduce heavy menstrual bleeding. Each tablet contains 500mg of mefenamic acid, which works by blocking the production of prostaglandins - natural chemicals in the body that cause inflammation, pain, and excessive menstrual flow. It is particularly effective for treating period pain (dysmenorrhoea) and reducing heavy periods (menorrhagia). The usual dose is one 500mg tablet three times daily with or after food to minimize stomach upset. Treatment should begin at the start of menstruation and continue for up to 7 days as needed. Mefenamic acid is also effective for relieving other types of pain including headaches, dental pain, muscular aches, and post-operative discomfort. This medication is suitable for adults and children over 12 years. As with all NSAIDs, it should be used at the lowest effective dose for the shortest duration necessary. Not suitable for those with a history of stomach ulcers, severe heart, liver or kidney problems, or aspirin/NSAID allergies.
| Medicine type | Oral tablet, taken by mouth |
| Active ingredient | Mefenamic acid 500mg per tablet |
| Licensed uses | Period pain (dysmenorrhoea), heavy menstrual bleeding (menorrhagia), and mild-to-moderate pain |
| Usual dose | One 500mg tablet three times a day, with or after food |
| Course length | Usually started at the onset of symptoms and continued for up to 7 days as needed |
| Prescription status | Prescription Only Medicine (POM) — requires an online consultation |
| Common side effects | Indigestion, nausea, diarrhoea, and headache |
| Not suitable for | History of stomach ulcers or GI bleeding, severe heart, liver or kidney impairment, or aspirin/NSAID allergy |
Mefenamic acid is a non-steroidal anti-inflammatory drug (NSAID) from the fenamate group. It works by blocking cyclo-oxygenase (COX) enzymes, reducing the body's production of prostaglandins — chemical messengers that trigger inflammation, pain signalling, and the womb contractions responsible for period pain and heavy bleeding. By lowering prostaglandin levels, it can ease cramping, reduce inflammation, and reduce the amount of blood lost during a period. It also has general pain-relieving properties, making it useful for other types of mild-to-moderate pain such as headaches, dental pain, and muscular aches.
Mefenamic acid is a prescription NSAID commonly used to relieve period pain (dysmenorrhoea) and reduce heavy menstrual bleeding (menorrhagia). It's also used for other types of mild-to-moderate pain, including headaches, dental pain, and muscular aches.
The usual dose is one 500mg tablet taken three times a day, with or after food. For period-related symptoms, treatment is usually started as soon as pain or bleeding begins and continued for up to 7 days, or as directed by your prescriber.
Most people notice pain relief within a few hours of taking a dose. For heavy menstrual bleeding, it can take one or two menstrual cycles of consistent use to see the full effect on blood loss.
You shouldn't take mefenamic acid alongside other NSAIDs, such as ibuprofen or aspirin, as this increases the risk of side effects. It can generally be taken alongside paracetamol. Always check with a pharmacist or prescriber if you're unsure about combining medicines.
Mefenamic acid isn't suitable for people with a history of stomach ulcers or gastrointestinal bleeding, severe heart, liver or kidney problems, inflammatory bowel disease, or an allergy to aspirin or other NSAIDs. It should also be used with caution during pregnancy. A prescriber will check your suitability during your online consultation.
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