Premenstrual syndrome (PMS, or Late Luteal Phase Dysphoric Disorder) is a cluster of symptoms, comprising physical and emotional changes, associated with the second part of menstrual cycle. Many women experience some symptoms, but for most women, these changes are minor, cause no severe distress and don't significantly affect social or occupational functioning (APA, 1987).

The essential feature of PMS is a cyclic pattern of severe emotional and behavioral symptoms occurring typically during the last week of the luteal phase and remitting within a few days after the onset of follicular phase (i.e., symptoms begin one week before and remit within a few days after the onset of menstruation). The diagnosis of PMS is not given if the symptoms are not sufficiently severe to cause major social or occupational impairment (APA, 1987).

According to DSM-III-R (APA, 1987), the diagnostic criteria are (the following is a citation):

1. In most menstrual cycles during the past year, symptoms occurred during the last week of the luteal phase and remitted within a few days of after onset of the follicular phase. In menstruating females, these phases correspond to the week before, and a few days after, the onset of menses. (In non-menstruating females who have had a hysterectomy, the timing of luteal and follicular phase may require measurement of circulating reproductive hormones.)
2. At least five of the following symptoms have been present for most of the time during each symptomatic late luteal phase, at least one of the symptoms being either (1), (2), (3), or (4):
1. marked affective lability, e.g., feeling suddenly sad, tearful, irritable, or angry
2. persistent and marked anger or irritability
3. marked anxiety, tension, feelings of being "keyed up," or "on edge"
4. decreased interest in usual activities, e.g., work, friends, hobbies
5. easy fatigability or marked lack of energy
6. subjective sense of difficulty in concentrating
7. marked change in appetite, overeating, or specific food cravings
8. hypersomnia or insomnia
9. other physical symptoms, such as breast tenderness or swelling, headaches, joint or muscle pain, a sensation of "bloating,", weight gain
3. The disturbance seriously interferes with work or with usual social activities or relationships with others.
4. The disturbance is not merely an exacerbation of the symptoms of another disorder, such as Major Depression, Panic Disorder, Dysthimia, or a Personality Disorder.
5. Criteria A, B, C, and D are confirmed by prospective daily self-rating during at least two symptomatic cycles (end of quotation).

According to some reports, 70 to 90% of women have recurrent menstrual problems. However, only 20 to 40% of women report some degree of interference with their usual functioning, and 2-5% are incapacitated by the symptoms.