Breast overflow is divided into pathologic and physiologic causes, mainly the following: First, women in the breastfeeding period may appear physiologic breast overflow problem, at the same time in the oral contraceptive pill may also lead to breast overflow, this is a physiologic symptom, basically do not need to be treated. Second, after the appearance of pituitary tumor or breast hyperplasia and other diseases, it will lead to the appearance of breast overflow, mainly due to the sex hormones and the body of prolactin increase, need to be timely treatment, to avoid the disease response more serious. Thirdly, when there are various diseases such as intraductal papilloma or breast cancer, it may also lead to the symptoms of breast overflow, and may also be accompanied by bloody milk, which are abnormal reactions, and it is best to seek medical treatment in time, so as to avoid affecting the normal life in the later stage.