Menorrhagia is the medical term for abnormally heavy or prolonged menstrual bleeding. Signs include soaking through a pad or tampon every one to two hours, passing clots larger than a coin, "flooding," needing double protection, or periods lasting more than seven days.
Because of the blood loss, heavy periods are a common cause of iron-deficiency anemia (watch ferritin and energy levels). Causes include hormonal changes — especially in perimenopause — fibroids, polyps, adenomyosis, and others, and it's treatable. See heavy periods. Any bleeding after menopause should be checked promptly.