Premenstrual syndrome - Causes of premenstrual syndrome (PMS)

The exact cause of premenstrual syndrome (PMS) is not fully understood, but there are a number of things that may contribute to the symptoms.

Hormone changes

During your menstrual cycle, levels of hormones such as oestrogen and progesterone rise and fall. Hormone changes are thought to be the biggest contributing factor to many of the symptoms of PMS.

The fact that PMS improves during pregnancy and after the menopause, when hormone levels are stable, supports this theory.

Chemical changes in the brain

It has also been suggested that the changes in hormone levels during the menstrual cycle may affect the levels of certain chemicals in your brain, such as serotonin.

Serotonin is known to help regulate your mood and make you feel happier, so a reduction in the level of serotonin caused by changes in hormone levels may explain the mood changes often associated with PMS.

It may also explain why a type of antidepressant medication that increases serotonin levels (known as selective serotonin reuptake inhibitors, or SSRIs) helps some women with PMS.

Lifestyle factors

There are also a number of lifestyle factors that can increase your risk of PMS. These are outlined below.

Weight and exercise

Research has shown that you are more likely to have PMS if you are obese (with a body mass index of more than 30) and if you do little exercise.

Read more about calculating your BMI and health and fitness.

Stress

You may find that your symptoms of PMS get worse as you become more stressed. While it is not a direct cause, stress can aggravate the symptoms of PMS.

Read more about understanding stress.

Diet

Eating too much of some foods and too little of others may also contribute to PMS symptoms. For example, too much salty food may make you feel bloated.

Alcohol and caffeinated drinks can disrupt your mood and energy levels.

Low levels of vitamins and minerals may also make your PMS symptoms worse.

Read more about maintaining a balanced diet.