Non-steroidal anti-inflammatory drugs (NSAIDs)
BMJ Group Medical Reference
This information is for people who have heavy periods. It tells you about non-steroidal anti-inflammatory drugs ( NSAIDs), a treatment used for heavy periods. It is based on the best and most up-to-date research.
Do they work?
Yes. About half the women who take non-steroidal anti-inflammatory drugs (NSAIDs) get lighter periods. NSAIDs can also help if you have painful periods.
What are they?
NSAIDs are a group of drugs that reduce inflammation and also act as painkillers.
Mefenamic acid (brand name Ponstan) is the NSAID most often used to treat heavy periods. Other NSAIDs (and their brand names) include:
You usually take these drugs each day of your period, starting on the first day and ending on the last day.
If you have had a stomach ulcer, or problems with NSAIDs in the past, your doctor may suggest avoiding NSAIDs.
The National Institute for Health and Clinical Excellence (NICE), the government body that decides which treatments should be available on the NHS, says NSAIDs are one of the first treatments women with heavy periods should consider. 
How can they help?
About half the women who take NSAIDs for heavy bleeding get lighter periods.  Their blood loss drops by about 20 to 50 percent. 
If you have painful periods, NSAIDs can help with that too. About 7 out of 10 women find that NSAIDs help their pain. 
NSAIDs might not work as well as two other drugs for heavy periods: tranexamic acid and danazol.     But your GP may be reluctant to prescribe danazol, since it can have unpleasant side effects. They may also work less well than the IUD (Mirena). 
How do they work?
Heavy and painful periods are sometimes caused by an imbalance of chemicals called prostaglandins. These chemicals work in many parts of your body. But, in your womb, they control the amount of the blood that you lose during your period.
NSAIDs can help correct this imbalance. This can reduce both the amount of blood you lose during your period and any pain you get.
To read more about what happens during your period, see What are heavy periods?