Premenstrual syndrome (PMS), also called premenstrual tension (PMT) is a collection of emotional symptoms, with or without physical symptoms, related to a woman’s menstrual cycle. While most women of child-bearing age (up to 85%) report having experienced physical symptoms related to normal ovulatory function, such as bloating or breast tenderness, medical definitions of PMS are limited to a consistent pattern of emotional and physical symptoms occurring only during the luteal phase of the menstrual cycle that are of “sufficient severity to interfere with some aspects of life”. In particular, emotional symptoms must be present consistently to diagnose PMS. The specific emotional and physical symptoms attributable to PMS vary from woman to woman, but each individual woman’s pattern of symptoms is predictable, occurs consistently during the ten days prior to the start of the menstrual period, and vanishes either shortly before or shortly after the start of menstrual flow. Two to ten percent of women have significant premenstrual symptoms that are separate from the normal discomfort associated with menstruation in healthy women. Culturally, the abbreviation “PMS” is widely understood in English-speaking countries to refer to difficulties associated with the menstrual period, and the abbreviation is used frequently even in casual and colloquial settings, without regard to medical rigor. In these contexts, the syndrome is rarely referred to without abbreviation, and the connotations of the reference are frequently more broad than the clinical definition. Premenstrual dysphoric disorder (PMDD) consists of symptoms similar to, but more severe than, PMS, and while primarily mood-related, may include physical symptoms such as bloating. PMDD is classified as a repeating transitory cyclic disorder with similarities to unipolar depression, and several antidepressants have been approved as therapy.