The nipple has been flowing clear water in the past few days may be serum prolactin increase, cystic hyperplasia of the breast, breast duct dilatation and other diseases, should be timely consultation to find out the cause of the disease. 1. Increased serum prolactin: Due to various reasons, the level of serum prolactin in the body is abnormally high, which is usually manifested as nipple milk overflow. 2. Breast cystic hyperplasia: a common benign breast lesion in women due to endocrine disorders, usually manifested by breast lumps, cyclic pain or abnormal nipple discharge, which is colorless or yellowish. 3. Dilatation of breast ducts: Inflammatory reaction caused by deformation and dilatation of milk ducts under the nipple, usually manifested as nipple discharge, pain, inflammation, etc. Surgery is usually required to remove the morbid tissues, and if there is abscess in the areola area. In addition to the above diseases, we should also consider the possibility of other diseases such as inflammation, tumor factors, etc. We should go to the hospital in time for relevant examinations to clarify the cause of the disease and carry out the treatment in conjunction with the actual situation.