Hard lumps in breasts during breastfeeding are considered to be caused by milk stagnation and mammary gland lesions. First of all, when breastfeeding the baby did not suck the milk inside the breast, and the patient did not squeeze out the residual milk in time, the residual milk has been stagnant in the breast inside the blockage formation of hard lumps, the longer the lumps the harder, the more serious it will be swollen, tingling. You need to use a hot towel to apply warm compresses, massage and squeeze or suction to suck out the milk, and the hard lumps can slowly soften and disperse. Secondly, it may be caused by the patient’s breast disease, such as breast hyperplasia, blocked milk ducts, etc., will appear hard lumps. Once the hard lumps appear in the breasts to exclude is caused by milk stagnation, we need to consider whether it is breast lesions, need to go to the hospital to do ultrasound to see whether the hard lumps have lesions and timely treatment.