Breast lumps during breastfeeding can usually be opened up by hot compresses and massage, but if they are hard and painful for a long time, you need to go to the hospital. Breast lumps during breastfeeding are often caused by excess milk and failure to pass the milk, it is recommended to pass the milk through hot compresses and massages to open the milk. Mothers can use hot towels to apply hot compresses to the breasts and massage the breasts moderately to stimulate the milk ducts to discharge the milk. If the milk is discharged as soon as possible, the lump will disappear. If the lump fails to subside for a long period of time and is painful, it may be mastitis or breast nodules, etc. You should consult a doctor to confirm the diagnosis through breast ultrasonography and follow the doctor’s instructions for treatment. During the breastfeeding period, you should pay attention to emptying the breast milk every time you breastfeed, and let your baby suckle or use a breast pump or bottle to suck out the retained milk as soon as possible.