Heavy menstrual bleeding (HMB), previously known as menorrhagia or hypermenorrhea, is a menstrual period with excessively heavy flow. It is a type of abnormal uterine bleeding (AUB).

Abnormal uterine bleeding can be caused by structural abnormalities in the reproductive tract, anovulation, bleeding disorders, hormonal issues (such as hypothyroidism) or cancer of the reproductive tract. Initial evaluation aims at determining pregnancy status, menopausal status, and the source of bleeding. One definition is bleeding lasting more than 7 days or the loss of more than 80 mL of blood heavy flow.

Treatment depends on the cause, severity, and interference with quality of life. Initial treatment often involve birth control pills. Tranexamic acid, danazol, progesterone IUDs, and NSAIDs are also helpful. Surgery can be an effective for those whose symptoms are not well-controlled with other treatments. Approximately 53 in 1000 women are affected by AUB.