Breast abscesses

What is a breast abscess?

An abscess is caused by a bacterial infection and consists of a collection of pus surrounded by swollen, inflamed tissue. Pus is a yellow or white, creamy liquid that contains bacteria, white blood cells, and dead tissue. Sometimes it is bloody. The pus of a breast abscess may also contain stagnant milk. A breast abscess may begin as a tender area covered by reddened skin. A lump then forms in the middle of it. Some abscesses start by appearing as a plugged duct, with a lump which then turns tender and red. Pus collects within 5 to 10 days and makes its way toward the skin. It may leak out through the skin by itself but ideally is drained by a health-care provider. The swollen area around the pus pocket then shrinks over a few weeks and finally disappears. An abscess can interfere with breastfeeding.

A) Describing a breast abscess

A small breast abscess (outlined in black).

A breast abscess is caused by a bacterial infection and consists of a collection of pus surrounded by swollen, inflamed breast tissue. Pus is a yellow-white, creamy liquid. Pus may also be bloody. The pus of a breast abscess consists of the following:

  • Bacteria
  • White blood cells
  • Dead tissue
  • Stagnant milk
  • Occasionally blood

An abscess is confirmed by a breast ultrasound. It is treated by drainage and antibiotics.

Mothers should continue to breastfeed on the normal breast and are encouraged to continue breastfeeding on the affected breast as long as the baby is not in direct contact with pus or infected tissue. The abscess may have a significant effect on the milk supply and the baby’s ability to breastfeed on that side.

The pain caused by a breast abscess can range from mild to severe.

Abscesses occur in an estimated 0.4% to 11% of breastfeeding mothers (Dener 2003; Dutta 2018). They are much less common than mastitis but having or having had mastitis increases the risk of an abscess (Yu 2018). 

The same approaches are used to prevent mastitis and abscesses.   

B) The development of a breast abscess

A large breast abscess.

1) Describing how a breast abscess develops

An abscess in the breast behaves in some ways like a pimple on your face:

  1. The infection starts with a red, tender spot on the skin. There may be other colour changes if the skin is darker.
  2. The spot becomes swollen, the redness increases, and it becomes more tender.
  3. A white blister containing pus develops in the centre of the red area.
  4. The white blister breaks open and pus drains out.
  5. The swelling, redness, and tender area disappear a few days later.

However, in a breast abscess:

  • The pus-containing blister is inside the breast and is called a pus pocket.
  • The affected area is much larger.
  • The whole process takes longer.

2) The stages of a breast abscess 

An abscess may start out acting like a mastitis:

  1. It starts with a tender area developing in the breast and is often covered by reddened skin. 
  2. However, within a few days, a lump forms in the middle of the area.

An abscess may start out looking like a plugged duct:

  1. A lump suddenly appears.
  2. However, within a few days, it becomes infected and increasingly painful and the overlying skin may be red.

As the abscess develops: 

  1. The lump hardens over several to ten days.
  2. The lump does not change with breastfeeding or expressing.
  3. Within 5 to 10 days, pus collects in the centre.
  4. The pus pocket may be 1 centimetre (1/2 inch) wide or larger. There may be one or more pus pockets.
  5. Over a few days, smaller pus pockets may join to make a larger one.
  6. The pus moves toward the skin, trying to make its way out. At this time, the centre of the abscess may feel a little softer than the area around it (fluctuant).
  7. The pus is drained by a health-care provider or leaks out through the skin.
  8. Mothers will quickly feel better once the pus is gone.
  9. The swollen area of the breast around the pus pocket shrinks and finally disappears. This can take up to one month.
  10. A small 1 cm (1/2 in) non-tender lump may remain at the site for months.

3) The appearance of a breast abscess

The amount of skin redness can vary. Unless the skin is very dark, there is nearly always redness over the lump. If the abscess is very deep in the breast and near to the chest, there may be no redness but this is rare. In such situations, the abscess may be mistaken for a plugged duct. Large abscesses may cause redness and swelling over most of the breast.

Occasionally, when the pus is moving toward the skin, there may be a slight bulge in that area of the breast. 

Once the pus is drained, the redness will slowly clear.


Dener C, Inan A. Breast abscesses in lactating women. World J Surg. 2003 Feb;27(2):130-3
Dutta R, Gowder RO. The prevalence and predisposing factors of mastitis in lactating mothers in puerperium. The New Indian Journal of OBGYN. 2018; 5(1): 28-32
Yu Z, Sun S, Zhang Y. High-Risk Factors for Suppurative Mastitis in Lactating Women. Med Sci Monit. 2018 Jun 19;24:4192-4197