Blockage of milk ducts is commonly caused by the following reasons: 1, lactating women fail to discharge milk in time, blocked in the milk ducts, resulting in blockage of milk ducts; 2, such as breast tissue or tumors in the milk ducts, compression of the milk ducts, can cause blockage; 3, mastitis caused by edema, inflammatory reaction, causing blockage of milk ducts; 4, surgical injury or trauma caused by damage to the milk ducts; 5, other factors: such as underwear such as fibrous tissue blocking the milk ducts. Patients with blocked milk ducts will experience local redness, pain, and even fever and lumps, etc. When these problems occur, they need to seek medical attention.