It is common in women who are breastfeeding, especially in first-time mothers. The reasons for this are as follows: 1. nipple cracking, due to incorrect breastfeeding posture, the baby bites through the nipple, thus causing cracking and pain. 2. inflammatory stimulation of the nipple, such as residual milk attached to the nipple, bacterial infection causes inflammation of the nipple, thus causing pain. 3. eczema of the nipple can also cause pain. 4. early in the breastfeeding period of new mothers, because they are not used to the baby’s sucking, can also cause swelling of the nipple, thus causing pain. 5. The nipples can also be irritated, such as the material of the underwear is rough, or allergic, which can also cause pain. 6. Being violently squeezed or traumatized can also cause pain.