What is mastitis?
Mastitis is a bacterial breast infection. It is most common in breastfeeding mothers. It can develop as early as the first two weeks after delivery but can develop any time during breastfeeding. One estimate is that 3% to 20% of mothers develop mastitis while breastfeeding. It starts quickly, with the breast becoming very tender and painful within a few hours. Parts of the breast may become red, warm, and swollen. Mothers may feel dizzy and weak with nausea, headaches, fever, and muscle aches. If there is a lump in the middle of the infected area, it may be a sign of a severe infection or the start of an abscess. Mastitis generally affects only one breast at a time. Mothers with mastitis should continue to breastfeed if possible and see their health-care providers.