Background. Premenstrual syndrome (PMS) is a recurrent luteal-phase condition characterized by physical, psychological, and behavioral changes of sufficient severity to result in deterioration of interpersonal relationships and normal activity.Premenstrual dysphoric disorder (PMDD) is considered a severe form of PMS.ackground. Premenstrual syndrome (PMS) is a recurrent luteal-phase condition characterized by physical, psychological, and behavioral changes of sufficient severity to result in deterioration of interpersonal relationships and normal activity.