Premenstrual dysphoric disorder (PMDD) is defined in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) as the presence of at least 5 of 11 symptoms with at least one of the symptoms being depressed mood, anxiety, affective lability, or irritability. The other symptoms include decreased interest in usual activities, poor concentration, fatigue, increased appetite, change in sleep, a sense of being overwhelmed or out of control, and physical symptoms such as breast tenderness. The symptoms must be present in the luteal (premenstrual) phase of the menstrual cycle, must resolve during the first few days of menses, and must have been present for at least 1 year. The symptoms should be severe enough to disrupt social and role functioning. The DSM-IV PMDD criteria include the recommendation that women prospectively rate their symptoms daily for two menstrual cycles to confirm the timing of the symptoms and the absence of a chronic underlying Axis I disorder. Many studies have identified irritability as the most frequently reported premenstrual symptom. It has been proposed that women with PMDD may comprise two subsets; one with predominant depressive symptoms, and another with predominant irritability.