Milk sores, i.e. acute suppurative mastitis, are often caused by milk stagnation and bacterial invasion during breastfeeding. Typical symptoms of milk sores are swollen breasts, elevated surface skin temperature, accompanied by generalized chills, swollen lymph nodes in the armpits, and fever. It is recommended to consult a doctor in time for standardized treatment. 1. Milk stagnation: this is an important cause of the disease. The causes of milk stagnation include: nipple dysplasia (too small or inverted) which prevents breastfeeding; too much milk or too little suckling by the baby, which prevents the milk from being emptied completely; and incomplete milk ducts, which affects the discharge of breastmilk. 2. Bacterial invasion: ruptured nipple, skin erosion around the areola, which is the main way of infection. Infant oral infection, sucking or sleeping with the nipple, resulting in bacteria directly into the milk ducts is also one of the ways of infection. The patient should consult a doctor in time and follow the doctor’s instructions to standardize the treatment of milk sores.