 2. Will fulfill screening criteria of the Premenstrual Screening Tool PSST for PMDD a. at least 1 of 4 core PMS symptoms rated severe, b. at least 4 additional premenstrual symptoms rated either moderate or severe, and c. at least 1of 5 functional items rated severe Steiner, Macdougall et al. 2003 3. Are diagnosed prospectively using the Daily Record of Severity of Problems - DRSP criteria by two full monthly cycles of daily symptom charting. A cycle will be considered symptomatic if the luteal phase mean score will be 30 greater than the mean follicular phase score Endicott et al.2006 