Itchy nipple overflow may be caused by dilated milk ducts, eczema of the skin of the nipple, breast cancer and so on. 1. Dilatation of the milk ducts: Nipple overflow caused by dilatation of the milk ducts may be due to the presence of a papilloma in the milk ducts, and the tumor may irritate the milk ducts causing discharge as it grows. In most cases, ultrasonography can confirm the diagnosis. If the patient’s symptoms are severe and the tumor is large, surgery is often required. 2. Skin eczema of the nipple: Skin eczema of the nipple, which mostly occurs during breastfeeding, can cause eczema-like changes due to the stimulation of the nipple by the milk, which stimulates the skin to produce secretions, as well as itching symptoms. 3. Breast cancer: when breast cancer infiltrates the ducts and causes ductal damage, capillary rupture and bleeding will lead to some bloody secretions in the ducts. In addition, breast hyperplasia and mastitis may also lead to similar symptoms. When patients experience nipple itching combined with nipple discharge, it is best for them to go to the hospital for further examination to clarify the specific cause.