Engorgement, mastitis, or a plugged duct can sometimes lead to a breast abscess. (This is unlikely if you continue to breastfeed your baby frequently during an episode of mastitis or when you have a plugged duct.) An abscess is a pus-filled area, like a boil under the skin. Your healthcare provider will suspect an abscess if the lump remains tender and does not go away with the treatment listed under plugged ducts and mastitis. An ultrasound of the breast may be necessary to locate an abscess deeper in the breast. An abscess often requires surgical drainage, plus antibiotic therapy.

In addition to the medical treatment recommended by your doctor, it's important to continue to empty the breast with the abscess. Depending on the location and the extent of the abscess, you may or may not be able to nurse on the infected breast. Your healthcare provider can help you determine whether this will be possible. If you are temporarily unable to breastfeed on the breast with an abscess, use an electric breast pump to empty the breast and nurse baby more frequently on the other breast. Apply moist heat to the affected area before nursing or pumping to help the milk flow.