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Last Updated: Mar 1, 2019


Breastfeeding has many benefits for babies, including improved nutrition and protection from childhood diseases. It even reduces the risk of diabetes later in life. Unfortunately, an infection called mastitis can interrupt breastfeeding or cause the mother to abandon it altogether.

lactiferous ducts highlighted in breast cross-section illustration

Mastitis is an inflammation of the breast characterized by pain, redness, and swelling. It can happen to any woman but is most common in those who are breastfeeding - especially within the first three months after a baby’s birth. It’s a very common condition that affects about one in 10 breastfeeding mothers in the United States.

Mastitis usually isn’t dangerous. But if it’s not treated quickly, it can cause an abscess (pocket of pus) to form inside the breast that may require surgical treatment. In rare cases, breast abscesses can be fatal, though almost all of these deaths occur in developing countries. In HIV-positive mothers, mastitis may increase the risk of spreading the disease to the baby.

The most common problem caused by mastitis is interruption or cessation of breastfeeding. The American Academy of Pediatrics recommends exclusive breastfeeding for the first six months of a baby’s life. However, the pain and exhaustion caused by mastitis may cause a mother to wean her baby before she planned to do so.

Causes and Risk Factors

There are two major causes of mastitis. They often occur together:

  • Milk stasis. This happens when a breast doesn’t empty completely during feedings. When milk is left to stagnate inside the ducts of the breast, it can lead to inflammation and increase the risk of infection.
  • Bacterial infection. Bacteria from the mother’s skin or baby’s mouth can enter the breast through either the milk duct or a crack in the skin around the nipple. (Fortunately, these germs aren’t harmful to the baby.)

Risk factors for developing mastitis include:

  • Sore or cracked nipples.
  • Using only one breastfeeding position, which may prevent the breast from draining completely.
  • Poor “attachment” of the infant at the breast. If a baby doesn’t grasp the nipple firmly with its mouth, it will have a hard time drawing milk out of the breast. Nursing a poorly attached baby can also irritate the nipples, increasing mastitis risk.
  • Feeding more often on one breast. This happens often, because many babies attach more easily to one side.
  • Missed or decreased frequency of feedings and milk expression.
  • Wearing a tight-fitting bra.
  • Being tired and run down.
  • Multiple birth (twins or triplets).
  • Having a personal history of mastitis.


Women who are coming down with mastitis often experience flu-like symptoms for a few hours before noticing any breast discomfort:

  • Fever of 101 degrees or greater, chills
  • Feeling tired and run down.

Breast symptoms appear later and usually affect only one side:

  • Pain, swelling, and warmth of the breast tissue
  • Pain or burning sensation (may be most noticeable while feeding)
  • Skin redness, often in a wedge-shaped pattern.

Diagnosis and Treatment

Women who experience mastitis symptoms should see a doctor right away. Early treatment can limit discomfort, minimize interruptions to breastfeeding and prevent complications.

Both obstetricians and primary care providers diagnose and treat mastitis. The mother may also be referred to a lactation consultant for breastfeeding advice and support.

Mastitis is usually diagnosed on history and physical exam. Sometimes a sample of the breast milk is cultured to determine which organism (germ) is causing the disease. The doctor will also rule out other causes of breast soreness, including:

  • Abnormalities in the baby’s mouth (cleft palate, short frenulum)
  • Nipple fissure
  • Blocked milk ducts
  • Yeast infection of the breast.

Treatment for mastitis include:

  • Oral antibiotics.
  • Antibiotic creams (to be applied to the breast skin).
  • Over-the-counter pain relievers like Tylenol, Advil, or Motrin IB.
  • Adjustments to breastfeeding technique that help to prevent milk stasis. These might include more frequent feedings, changing positions, and improving the baby’s attachment.
  • Rest and fluids.
  • Emotional support. Mastitis can be frustrating, can cause anxiety, and can make a woman feel very sick.

Mothers with mastitis should continue breastfeeding (or if that’s not possible, pumping or hand expressing their milk). Moving fresh milk through the breast will help clear out the infection. Applying warm compresses or showering beforehand can help to empty the infected breast and promote healing.

Women with mastitis should see a doctor again if their symptoms don’t improve within a few days. In these cases, the doctor may want to rule out inflammatory breast cancer, a rare cancer that has symptoms similar to mastitis. This is usually done by a mammogram (imaging test) and tissue biopsy (minor surgery).

With proper treatment and support, almost all women recover from mastitis and are able to continue breastfeeding. During and after recovery, it’s important to make sure the breast is emptied regularly to prevent the condition from recurring.


Good breastfeeding technique helps to prevent mastitis. Some tips for mothers include:

  • Drain one breast completely before switching to the other.
  • If the baby doesn’t finish the second breast, start on that one next time.
  • Change positions from time to time.
  • Make sure the baby latches on correctly.
  • If you have difficulties, consider working with a lactation consultant.


  • Diseases and Conditions: Mastitis (July 2012). Mayo Foundation for Medical Education and Research. Retrieved May 22, 2015 from
  • Mastitis (May 2015). American Cancer Society. Retrieved May 29, 2015 from
  • Mastitis: Causes and Management (2000). World Health Organization. Retrieved May 29, 2015 from
  • Spencer, Jeanne P. Management of Mastitis in Breastfeeding Women (Sept. 2008). American Academy of Family Physicians. Retrieved May 29, 2015 from

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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.