Primary dysmenorrhea is defined as painful menstruation in the absence of pelvic pathology. Characterized by recurrent, crampy, lower abdominal pain during menstruation, it is the most common reason for gynecologic visits, affecting 50% to 90% of women, half of whom describe their pain as moderate to severe. 1 Secondary dysmenorrhea refers to the same clinical features of pain during menstruation, but is attributable to pelvic pathology, such as endometriosis, fibroids, adenomyosis, and congenital anatomic abnormalities. Management of primary dysmenorrhea is directed toward excluding other causesofsymptomsandidentifying medical therapies that control the patient's symptoms. Despite its high prevalence, dysmenorrhea is often underdiagnosed, inadequately treated, and normalized even by patients themselves, who may accept the symptoms as an inevitable response to menstruation.Primary dysmenorrhea generally begins in adolescence after ovulatory cycles are established. The associated pain arises from release of excess prostaglandins at the time of endometrial sloughing. Higher levels of prostaglandins have been found in endometrial tissue and menstrual fluid of women with dysmenorrhea compared with asymptomatic women. The increased level of prostaglandins at the time of menstruation is theorized to cause myometrial hypercontractility resulting in hypoxia and ischemia of uterine muscle and the perception of pain, as well as the cause of systemic symptoms often associated with dysmenorrhea, such as nausea and diarrhea.In a population-based survey of women older than 18 years with primary dysmenorrhea, more than half of the respondents described symptoms limiting their activities and 17% reported missing school or work as a result. 2 Dysmenorrhea is the most common cause of short-term absence from school in adolescent girls, and about 1 in 8 girls aged 14 to 20 years report missing school or work as a result of dysmenorrhea. 1 Other cross-sectional studies have demonstrated similar findings of dysmenorrhea affecting relationships, functioning and productivity, and contributing to absenteeism. Despite the significant effects on quality of life, the prevalence of primary dysmenorrhea is considered to be underestimated because women frequently do not seek medical treatment because of the commonly held belief that pain is an expected part of menstruation.The evaluation and diagnosis of women with primary dysmenorrhea does not require specialization in women's health or pelvic pain. In many cases, a diagnosis of primary dysmenorrhea can be reached by obtaining a detailed medical, psychosocial, and gynecologic (including menstrual and sexual) history. 1 A complete menstrual history should include age at menarche; duration of bleeding; intervals between menses; assessment of menstrual flow; and history of associated symptoms, such as pain, nausea, diarrhea, and fatigue, that includes timing of onset, severity of pain, and effects on daily activities. The onset of primary dysmenorrhea typically begins 6 to 24 months after menarc...