Mastitis is as an infection of the breast tissue. It occurs in 2% to 10% of breastfeeding (lactating) women, but it may also occur in women who are not lactating.

Anatomy of the Breast

Each breast has 15 to 25 lobules made up of milk-producing cells. Ducts connect the lobules to the nipple and transport the milk. The ducts are open at the nipple surface, although not visible to the eye unless milk is excreted. The darker area around the nipple is called the areola. On the areola are little raised bumps, called Montgomery glands, which produce fluid to moisturize the nipple.

Causes of Mastitis

  • Trauma or chafing to the nipple, which can introduce bacteria into the nipple through the ducts
  • Prolonged engorgement, resulting in retention of milk within the breast
  • Poor latching with resulting poor milk removal from the breast
  • Smoking, which is associated with clogging or plugging of the ducts due to the toxic substances in cigarette smoke
  • Nipple piercings, which can introduce another pathway for bacteria into the nipple or breast
  • Idiopathic (unknown or spontaneous origin)

Signs and Symptoms of Mastitis

  • Hard, red, tender, warm-to-touch, swollen area on the breast
  • Fever (100 degrees or higher)
  • Flu-like symptoms (fatigue, chills, body aches, headaches, loss of appetite)
  • Usually in 1 breast only
  • May be sudden or rapid onset

Caution—Mastitis can lead to a breast abscess, which is a condition that usually requires needle aspiration or surgical drainage. A breast abscess presents with symptoms of mastitis, as well as a tender mass that can be felt within the breast. Pus-like discharge may drain from the nipple.

Management of Mastitis

  • Continue breastfeeding or pumping. It is very important to keep the breasts emptied of milk.
  • Improve positioning and latching of the infant to the breast, if breastfeeding.
  • Manage pain with over-the-counter acetaminophen or ibuprofen.
  • Use cold compresses or ice packs to reduce pain and swelling.
  • Rest, eat a healthy diet, and increase fluid intake.
  • See your healthcare provider for evaluation and antibiotic therapy.


Cibulka N.J, Barron ML. Guidelines for Nurse Practitioners in Ambulatory Obstetric Settings. New York, NY: Springer Publishing Company;2013:154-156.

Dixon JM. Nonlactational mastitis. In: Post TW, ed. UptoDate. Waltham, Mass.: UptoDate;2015.