Most breast abscesses are linked to mastitis (inflammation of the breast). Mastitis usually affects women who are breastfeeding, although it can sometimes also occur in women who are not breastfeeding.
Women who smoke cigarettes have an increased risk of developing mastitis and breast abscesses outside of pregnancy and breastfeeding. This condition is known as periductal mastitis.
See the Health A-Z topics about Mastitis (breastfeeding) and Mastitis (non-breastfeeding) for more information.
How breast abscesses form
Most abscesses are caused by a bacterial infection. The bacteria may enter the breast and milk duct through a small crack or break in the skin of the nipple. Such cracks may appear during breastfeeding. However, sometimes the infection is caused by an overgrowth of bacteria that normally exist quite harmlessly within the milk ducts. An overgrowth of bacteria might result from a collection of stagnant milk in a blocked milk duct.
When bacteria enter your body, your immune system (the body’s natural defence system) tries to fight them off by sending white blood cells to the affected area. As the white blood cells attack the bacteria, some of the tissue at the site of the infection dies, creating a small hollow, like a pocket.
The hollow fills with pus to form an abscess. The pus contains a mixture of dead tissue, white blood cells and bacteria. The abscess may get larger and more painful as the infection continues and more pus is produced.
