The mammary gland is the lactating organ of women. Under normal circumstances, it secretes milk only during lactation, and generally does not secrete fluid during non-lactation periods. Nipple overflow is a common symptom of breast disease, and can be divided into physiological overflow and pathological overflow. Physiological overflow refers to the phenomenon of lactation during pregnancy and lactation, bilateral nipple overflow caused by oral contraceptives or sedative drugs, and unilateral or bilateral small amounts of overflow in postmenopausal women. Pathological overflow is defined as intermittent, persistent, from months to years of nipple overflow from one or more ducts on one or both sides under non-physiological conditions. Clinically, the incidence of non-lactating nipple discharge is about 5-8%. There are many causes of nipple discharge, which can be either physiological or pathological. Certain systemic diseases can cause nipple overflow, such as pituitary tumors, hyperthyroidism or oral hormonal drugs; non-neoplastic breast diseases such as ductal dilation of the breast; tumorigenic or neoplastic lesions of the breast such as intraductal papilloma, breast cancer, etc. can cause nipple overflow. Etiology: 1, mesencephalic diseases or pituitary lesions, such as mesencephalic and nearby tissue tumors, prolactin adenomas, pineal tumors, hyperpituitarism, acromegaly, etc.; 2, endocrine system diseases, such as primary hypothyroidism, adrenal tumors, etc.; 3, chest diseases, such as chronic mastitis, chest herpes zoster, etc.; 4, side effects of drugs, such as chlorpromazine, morphine, reserpine, morpholine, gastroflucan, etc. Gastrodia and hormonal drugs such as contraceptives can cause endocrine dysfunction and stimulate prolactin secretion, resulting in breast overflow; 5. Local stimulation of the breast and systemic stress reactions, such as frequent playing or sucking of the nipple, severe trauma and other factors, can also lead to a transient increase in prolactin and cause breast overflow.