Breast swelling, pain and fever during breastfeeding are usually acute mastitis. If the blood count and C-reactive protein are high and there is a lump in the breast, you should give oral anti-fever medication, such as ibuprofen suspension, and anti-inflammatory medication that does not affect the child’s milk intake, such as cephalosporins. The breast that has a lump can be warmed with magnesium sulfate, and the opposite breast can be emptied by the child. With aggressive and effective treatment, most of them can achieve fever reduction as well as lump remission. If oral medication is not effective, intravenous fluids can be given to provide effective anti-inflammatory and antipyretic treatment.