Also known as premenstrual tension, premenstrual syndrome (PMS) is the combination of physical and psychological symptoms that many women experience in the week or so before menstruation.
The cause is unknown, but it is thought to be linked to changing levels of hormones.
Symptoms can vary from woman to woman, and also from month to month, and may be severe enough to disrupt normal everyday activities.
No single treatment has proved consistently successful. Treatments that may be suggested include lifestyle changes, relaxation techniques, medication to relieve symptoms, psychological therapy, and hormone treatment, such as the combined oral contraceptive pill.