The single side of the breast single hole extrusion of milk not extrusion on no may be diet unreasonable reasons, but also may be mastitis, breast cancer and other diseases caused by. 1, physiological factors: in the breastfeeding period of women, may be due to dietary irrationality and other factors, can not supply sufficient nutrients, then there will be less milk. When squeezed by hand, there will be the phenomenon of milk being squeezed out of a single hole on one side of the breast without squeezing. 2, Mastitis: Mastitis usually occurs in the breastfeeding stage, usually is mainly infectious inflammation performance, can be accompanied by obvious symptoms of redness, swelling and heat pain. When the milk is stagnant, it will cause the milk to be unable to be discharged smoothly, and it will also cause the milk to block the breast ducts, so there is a situation where the milk is squeezed out of a single hole on one side of the breast without squeezing. 3, breast cancer: if in the non-pregnancy period, or breastfeeding period, the breast unilateral single hole extrusion of breast milk not squeeze no may also be due to breast cancer. This kind of patients can show nipple discharge, the nature of the liquid can be presented as hemorrhagic, or watery changes. There are many reasons for unilateral breast milk extrusion, and it is recommended that patients seek medical attention to avoid delays.