The hallmark feature of premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD) is the predictable, cyclic nature of symptoms or distinct on/offness that begins in the late luteal phase of the menstrual cycle and remits shortly after the onset of menstruation. PMDD is distinguished from PMS by the severity of symptoms, predominance of mood symptoms, and role dysfunction, particularly in personal relationships and marital/family domains. Several treatment modalities are beneficial in PMDD and severe PMS, but the selective serotonin reuptake inhibitors (SSRIs) have emerged as first-line therapy. The SSRIs can be administered continuously throughout the entire month, intermittently from ovulation to the onset of menstruation, or semi-intermittently with dosage increases during the late luteal phase. These guidelines present practical treatment algorithms for the use of SSRIs in women with pure PMDD or severe PMS, PMDD and underlying subsyndromal clinical features of mood or anxiety, or premenstrual exacerbation of a mood/anxiety disorder.