Breast inflammation or infection is also called "mastitis". The nipple, the ducts draining to it, or deeper sites under the skin may be involved and abscesses can develop.

Mastitis is most common in women who are breast-feeding - a duct becomes blocked causing milk to accumulate, which can lead to inflammation and infection. Early treatment is with antibiotics. If an abscess forms, it is drained either with a needle or an incision. Some women nearing menopause develop inflamed ducts beneath the nipple. Smoking is associated with a recurrent infection in the ducts directly under the nipple and frequently requires removal of the duct system directly under the nipple.