Hi, thanks for your query, Mefenamic acid and naproxen are members of a group of drugs known as non-steroidal anti-inflammatory agents (NSAIDs). Although most often used for relief of muscle and joint pain, they also reduce menstrual pain and can reduce blood flow by altering the production of substances called prostaglandins which play an important role in menstruation. However, their effect on menstrual flow is only moderate, reducing blood loss by, on average, 25 - 30 per cent, which may be insufficient if periods are very heavy. These drugs are most effective if you start taking them just before the onset of bleeding and so timing may be difficult if your periods start without warning.

You are most likely to benefit from this type of drug if your periods are very painful as well as heavy and your cycle is regular. Mefenamic acid and naproxen are only available on prescription by a GP. Ibuprofen, which is available over the counter, belongs to the same group of drugs and is effective in relieving menstrual cramps, but is not usually helpful in reducing heavy bleeding. Drugs in this category may not be suitable for women prone to stomach upsets.

Tranexamic acid

Tranexamic acid acts on the mechanisms in the uterine lining which control blood loss during menstruation. It is available only on prescription from a GP. It reduces menstrual blood loss by an average of 50 per cent and is thus more effective than mefenamic acid or naproxen, although it does not relieve menstrual cramps.

It has the advantage that it is effective if you begin taking it once heavy bleeding has started, so you don’t need to know exactly when that will happen. You need to take two tablets three or four times daily and continue taking them regularly during the days that your period is normally heavy (usually between three and five days). If you stop too soon the heavy bleeding may recur.

Side effects are few although it may cause gastric upsets. It is not recommended for women with a history of thrombosis. If your periods are also very painful tranexamic acid can be taken together with a pain killer or an NSAID.
Regards , Dr.Sharmila