Premenstrual syndrome (PMS) is the name given to the physical, psychological and behavioural symptoms that can occur in the two weeks before a woman's monthly period. It is also known as premenstrual tension (PMT).
There are many different symptoms of PMS, but typical examples are bloating, breast pain, mood swings, feeling irritable and loss of interest in sex.
These symptoms usually improve when your period starts and disappear a few days afterwards.
Nearly all women of childbearing age have some premenstrual symptoms, but women in their late 20s to their early 40s are most likely to experience PMS.
Around 1 in every 20 women have symptoms that are severe enough to stop them living their normal lives. This is often the result of a more intense type of PMS known as premenstrual dysphoric disorder (PMDD).
Read more about the symptoms of PMS.
When to see your GP
You should see your GP if you are finding it difficult to deal with the symptoms of PMS. They can help determine if you have PMDD and may be able to offer you advice and treatment to manage the symptoms you're experiencing.
Why it happens
The exact cause of PMS is not fully understood. However, it is thought to be linked to the changing levels of hormones in the body during a woman's menstrual cycle.
The fact that PMS improves during pregnancy and after the menopause, when hormone levels are stable, supports this theory.
Certain lifestyle factors, such as lack of exercise, stress and a poor diet, are also thought to aggravate the symptoms of PMS.
Read more about the causes of PMS.
Managing PMS symptoms
There is no cure for PMS, but if your symptoms are not severe, certain lifestyle changes can help you manage them. These include:
Psychological therapy or hormone medications may be recommended in more severe cases.
Read more about treating PMS.