Breast abscesses are painful, pus-filled lumps under the skin of the breast. They are a complication of a breast infection, which is called mastitis. Mastitis tends to affect women who are breastfeeding, but anyone can develop this type of infection and a resulting abscess.

What causes an abscess in your breast?

Breast abscess is caused by a bacterial infection. The most common type of bacteria involved in a breast abscess is Staphylococcus aureus. Bacteria enter through a scratch in the skin or a tear in the nipple.

How do I know if I have a breast abscess?

When a subareolar breast abscess first develops, you may notice some pain in the area. There will likely be a lump under the skin and some swelling of nearby skin. Pus may drain out of the lump if you push on it or if it's cut open. If left untreated, the infection can start to form a fistula.