Nipple single hole overflow may be due to intraductal papilloma, breast hyperplasia, breast cancer and other reasons, specific need to go to the hospital for further examination, timely and clear cause, symptomatic treatment. 1. Intraductal papilloma: Intraductal papilloma belongs to epithelial tumor, the cause of this lesion is not clear. This disease usually has no obvious specific symptoms in the early stage, some patients will appear such as overnight or breast lumps, when the lesion occurs in one side, it will lead to unilateral nipple discharge. 2. Breast Hyperplasia: The onset of breast hyperplasia is usually related to the endocrine dysfunction of the patient, this disease can occur unilaterally or bilaterally in the breast, which will cause the patient to develop breast lumps, nodules, breast pain, etc., and some patients will also be accompanied by the symptom of breast overflow. 3. Breast cancer: the cause of breast cancer is not clear in the clinic, and there are usually no obvious symptoms in the early stage, some patients will have breast skin abnormalities, breast lumps, nipple discharge and areola abnormalities. There are many other causes of unilateral nipple discharge, so you should go to the hospital in time for examination and treatment, and avoid blindly using drugs on your own.