Not breastfeeding with milk may be caused by non-disease factors, such as physiological factors, medication side effects, but it may also be caused by disease factors, such as ductal dilatation of the breast, prolactinoma and so on. 1. Non-disease factors: (1) Physiological factors: women in ovulation, pregnancy, before and after menopause, etc., can make the body’s hormone levels change, resulting in the secretion of milk from the breast gland ducts. (2) drug side effects: women who take spironolactone, birth control pills and other hormonal drugs, can make the body estrogen levels increase, stimulate prolactin secretion, the phenomenon is not breastfeeding also have milk. 2. Disease factors: (1) Dilatation of mammary ducts: the cause of the disease is still unclear, and it is mostly related to obstruction of milk ducts and bacterial infection. The disease starts slowly, and the main clinical manifestations are localized breast lumps, nipple inversion, breast pain, etc., and the patients will have milk secretion even if they are not breastfeeding. (2) Prolactinoma: the pathogenesis is still unknown, and it is related to the activation of tumor genes and the inactivation of oncogenes, etc. It can cause nipple discharge, menstrual disorders, and reproductive dysfunction (e.g., loss of libido, infertility, etc.), and is accompanied by weight gain. In addition, breast cancer and other diseases can also cause breast milk that is not during breastfeeding. It is recommended to go to the hospital in time to find out the cause of the disease and receive treatment as early as possible after eliminating physiological factors.