Heavy periods, also known as menorrhagia, are a common menstrual symptom. They are characterized by regular periods that last for the usual 5 days or so, but are heavier than normal. The average blood loss during a menstrual cycle is 30-80 ml, but a period may be considered heavy if a woman experiences a sudden gush of blood, requiring her to use a tampon or pad urgently, or if she has to change these protective devices frequently. Heavy periods can be caused by excessive physical activity, emotional stress, irregular diet, external heat, surgery, or post-partum conditions. In Chinese medicine, heavy periods are differentiated from flooding and trickling, which are more difficult to treat. The pathology of heavy periods may involve Qi deficiency, Blood-Heat, or Blood stasis, and treatment principles include tonifying Qi, clearing Heat, and stopping bleeding.