1. Candida albicants
Candida (also called yeast, monilla or thrush) is a fungus that thrives in warm, dark, moist environments, such as the mucus membranes of the mouth and vagina, the diaper area, skin folds, bra pads, and on persistently wet nipples.

Candidosis of the nipple in the nursing mother is associated with infantile oropharyngeal candidiasis. Nipple candidosis almost always is bilateral, with the nipples appearing bright red and inflamed, with the look and feel of being sunburned or on fire. Unlike a painful-with-nursing cut or abrasion from local trauma by the infant (incorrect latch-on), nipple candidosis hurts between feedings. Merely having the clothing brush against the nipples is painful.

Suspect candida as the cause of sore nipples if:

  • Nipples are extremely sore, burning, itching, red or blistery.
  • Shooting pains in breasts during or just after feeding(especially during milk ejection reflex).
  • The usual remedies for sore nipples aren’t working.
  • Baby has oral thrush (white, cottage-cheese-like patches on the tongue and sides of the mouth) and/or a yeasty diaper rash.
  • Nipples suddenly become sore after a period of pain-free breastfeeding.
  • One is taking, or has just finished taking, a course of antibiotics. Yeast infections are common following antibiotic treatment.

2. Staphylococcus aureus
Breast infections are usually caused by a common bacteria (Staphylococcus aureus) found on normal skin. The bacteria enter through a break or crack in the skin, usually on the nipple. The infection takes place in the fatty tissue of the breast and causes swelling. This swelling pushes on the milk ducts. The result is pain and lumps in the infected breast.