Plugged ducts

Is this a plugged duct?

A plugged duct is a tender, hard lump that suddenly develops in one breast. This happens when milk is unable to get out of the breast with breastfeeding or expressing and causes pain and swelling. The lump is generally round with regular edges that are easily felt and between the size of a marble and one-third of the breast. It may develop along with a milk pimple.  The plug may clear within a day or so after forming if the milk can leave the breast. If not, the body will dissolve the milk but this can take several weeks. Having a plugged duct can increase the risk of a reduced milk supply, mastitis, or an abscess. 

A) Describing plugged ducts and galactocoeles

A plugged duct is a tender, hard lump that suddenly develops in one breast.  

Plugged ducts are caused by milk that is not able to get out of the breast with breastfeeding or expressing. The excess milk causes painful swelling in the duct and inflammation around it. 

A persistent milk-filled lump is called a galactocoele (Vashi 2013). It can contain milk in different stages of being reabsorbed into the body. The milk can even change to a semi-solid cheesy material.

Plugged ducts and galactocoeles are not infected when they develop but there is a risk that they can become infected once established. 

Plugged ducts and breast infections (mastitis or a breast abscess) are somewhat related as a plugged duct:

  • May lead to a breast infection.
  • May be misdiagnosed as a breast infection.
  • May actually be a breast infection and not a plugged duct.

The reason for a plugged duct forming is not known. Some health-care providers have suggested the duct blocks because of inflammation due to certain types of bacteria within the breast (AV10subacute mastitis).

B) Behaviour of a plugged duct

A plugged duct:

  • Is felt as a round lump with clear edges.
  • Is between the size of a marble and one-third of the breast.
  • Comes on quickly.
  • Is mildly to very tender.
  • Is slightly warm.
  • Can cause slight redness of the breast that may become redder with massage.
  • Does not cause mothers to have a fever or feel unwell.
  • May develop around the same time as a milk pimple.

Ideally, the plug is emptied as soon as possible to lower the risk of a reduced milk supply or a breast infection. Most plugged ducts will clear within three days. If it is not cleared quickly, the body will dissolve it, but this can take up to several weeks.

In rare cases, breast cancer may behave like a plugged duct (Siddiqui 2015).

Please see your health-care providers if:

  • You are in a lot of pain.
  • The pain is increasing.
  • The area is becoming more red.
  • You feel unwell.
  • The plugged duct does not clear within three days.

C) A poorly-drained breast

Occasionally a part of one breast may not drain well causing pain and swelling. The area may be somewhat lumpier and fuller with edges that are a little hard to feel. The pain and swelling can be made worse by a mother's attempts to empty the area through vigorous breast massage and compression.

Other than making sure the baby is breastfeeding effectively and the mother is expressing effectively, these areas will settle with a little time and support from warm compresses or cool cabbage compresses and over-the-counter medication, such as acetominophen or ibuprofen. 


Siddiqui B, Faridi SH, Arif SH, et al. Primary hydatid disease of the breast clinically masquerading as a galactocele: A case report. J Transl Int Med. 2015 Apr-Jun;3(2):82-84
Vashi R, Hooley R, Butler R, et al. Breast imaging of the pregnant and lactating patient: physiologic changes and common benign entities. A J Roentgenology 2013; 200(2)