A menstrual disorder is characterized as any abnormal condition with regards to a person's menstrual cycle. There are many different types of menstrual disorders that vary with signs and symptoms, including pain during menstruation, heavy bleeding, or absence of menstruation. Normal variations can occur in menstrual patterns but generally menstrual disorders can also include periods that come sooner than 21 days apart, more than 3 months apart, or last more than 10 days in duration. Variations of the menstrual cycle are mainly caused by the immaturity of the hypothalamic-pituitary-ovarian (HPO) axis, and early detection and management is required in order to minimize the possibility of complications regarding future reproductive ability.

Though menstrual disorders were once considered more of a nuisance problem, they are now widely recognized as having a serious impact on society in the form of days lost from work brought about by the pain and suffering experienced by women. These disorders can arise from physiologic sources (pregnancy etc.), pathologic sources (stress, excessive exercise, weight loss, endocrine or structural abnormalities etc.), or iatrogenic sources (secondary to contraceptive use etc.).