Nipple out of the clear water turned yellow water to consider may be due to nipple overflow caused by nipple overflow, nipple overflow of the common causes include breast hyperplasia, breast tumors, inflammation of the mammary gland and so on. 1. Mammary hyperplasia: the cause of the disease is mainly related to endocrine dysfunction, which is mainly manifested as yellowish, white or colorless plasma. In addition, there may be breast lumps, breast pain and other manifestations. 2. Breast tumor: breast tumor includes benign and malignant tumors, benign tumors such as intraductal papilloma, etc., which often show yellow, dark brown or bloody overflow; malignant tumors such as breast cancer, in addition to nipple overflow, it can also show specific manifestations such as “dimple sign” and “cellulite change”. Malignant tumors such as breast cancer, in addition to nipple discharge, may also show “dimple sign”, “orange peel-like change” and other specific manifestations. 3. Inflammation of the mammary glands: including lactation mastitis and non-lactation mastitis, lactation mastitis is mostly characterized by symptoms such as redness, swelling, heat and pain in the breast; non-lactation mastitis includes breast lumps, inverted nipples, nipple discharge, and pain in the mammary glands, etc. In addition, there are other causes that may lead to mastitis. In addition, there are other reasons that may cause the nipple to become yellowish water, when the above situation occurs, it is recommended to consult a doctor for examination, to clarify the cause of the problem, and then follow the doctor’s instructions to deal with it.