Breast abscesses are often linked to mastitis – a condition that causes breast pain and swelling (inflammation), and usually affects women who are breastfeeding.
Infections can occur during breastfeeding if bacteria enter your breast tissue, or if the milk ducts (tiny tubes) become blocked. This can cause mastitis which, if not treated, can result in an abscess forming.
Women who aren't breastfeeding can also develop mastitis if bacteria enter the milk ducts through a sore or cracked nipple, or a nipple piercing.
White blood cells are sent to attack the infection, which causes tissue at the site of the infection to die. This creates a small, hollow area that fills with pus (an abscess).