For healthy women, breast lumps during breastfeeding are generally formed due to milk stagnation, so you can choose to apply hot compresses, and cold compresses are not recommended. However, it should be noted that some breast lumps in breastfeeding women are breast fibroids and breast hyperplasia, and the effect of either cold compresses or hot compresses is very limited at this time. Hot compresses are beneficial for milk stasis because the blood vessels expand when the temperature of the breast rises, and the blood supply to the breast increases accordingly. Hot compresses can also relax the ducts and alveoli of the breast, which is conducive to the discharge of milk. At the same time, due to the increase in temperature, the milk accumulated in the lump is in a good state of liquefaction, which is beneficial to the evacuation. If hot compresses do not relieve breast lumps, it is important to note that there may be problems such as breast fibroids. The reason why cold compresses are not beneficial for lactation is that when the temperature of the breast is lowered, the blood vessels contract and the blood circulation is reduced. Women with hard lumps in the breast during breastfeeding should use hot compress treatment methods and also pay attention to a low-fat, high-fiber diet with more whole grains and vegetables, but they need to control the intake of animal protein. Pay attention to adjusting your mind and exercise appropriately to enhance your physical fitness.