Definition

Mastitis is painful swelling and redness in the breast. It is most common among women who are breastfeeding. It usually occurs in one breast at a time, but it can occur in both breasts at the same time.

Mastitis can occur in women who are not breastfeeding. However, this fact sheet will focus on symptoms and treatment of mastitis that occurs with breastfeeding.

Mastitis Copyright © Nucleus Medical Media, Inc.

Causes

Mastitis is often caused by breast milk trapped in a milk duct. The trapped breast milk can irritate the tissue around it and cause swelling and pain.

Mastitis can also be caused by bacteria. The bacteria can enter the breast through the milk duct or cracks in the skin of nipple. Once the bacteria enter the tissue, it can grow and cause an infection.

Risk Factors

Factors that may increase your chances of mastitis:

• Previous mastitis
• Abrasion or cracking of the breast nipple
• Yeast infection of the breast
• Pressure on the breasts, caused by:
  • Wearing a bra or clothing that is too tight
  • Sleeping on the stomach
  • Holding the breast too tightly during feeding
  • Baby sleeping on the breast
  • Exercising, especially running, without a support bra
  • Carrying a bag with a cross chest strap
• Anything that causes too much milk to remain in the breast, including:
  • Irregular breastfeeding
  • Missed breastfeeding, which may cause swelling of the breast
  • Baby's teething
  • Use of supplemental bottle feeds
  • Incorrect positioning of the baby during feedings
  • Abrupt weaning

Symptoms

Mastitis may cause:

• Redness, tenderness, or swelling of the breast
• Fever
• Fatigue
• Aches, chills, or other flu-like symptoms
• A burning feeling in the breast
• A hard feeling or tender lump in the breast
• Pus draining from the nipple

Diagnosis

You will be asked about your symptoms and health history. A physical exam will be done. If the diagnosis is uncertain, or if mastitis recurs, your doctor may do:

• Culture of breast milk or nipple discharge—to look for bacteria
• Breast ultrasound —if a pocket of pus is suspected

Other conditions may cause similar symptoms. Your doctor may want to do tests to rule these out. Options may include:

• Biopsy of the affected area
• Mammogram or x-ray of the breast

Treatment

Treatment may include:

Prevention

To help reduce your chances of mastitis:

• Breastfeed frequently.
• Use a breast pump when you skip feedings.
• Wash your hands and breast nipple before breastfeeding.
• Avoid wearing bras or clothing that is too tight.
• Avoid sleeping on your breasts, or allowing a baby to sleep on your breasts.
• If your nipples crack, apply lotion or cream as advised by your doctor.