Mastitis, which mainly affects breast-feeding women, causes redness, swelling and pain in one or both breasts.
Mastitis is an inflammation of breast tissue that sometimes involves an infection. The inflammation results in breast pain, swelling, warmth and redness. You might also have fever and chills.
Mastitis most commonly affects women who are breast-feeding (lactation mastitis). But mastitis can occur in women who aren't breast-feeding and in men.
Lactation mastitis can cause you to feel run down, making it difficult to care for your baby. Sometimes mastitis leads a mother to wean her baby before she intends to. But continuing to breast-feed, even while taking an antibiotic to treat mastitis, is better for you and your baby.
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Signs and symptoms of mastitis can appear suddenly. They may include:
- Breast tenderness or warmth to the touch
- Breast swelling
- Thickening of breast tissue, or a breast lump
- Pain or a burning sensation continuously or while breast-feeding
- Skin redness, often in a wedge-shaped pattern
- Generally feeling ill
- Fever of 101 F (38.3 C) or greater
When to see a doctor
See your doctor if you have breast symptoms that concern you.
Milk that is trapped in the breast is the main cause of mastitis. Other causes include:
A blocked milk duct. If a breast doesn't completely empty at feedings, one of your milk ducts can become clogged. The blockage causes milk to back up, leading to breast infection.
Bacteria entering your breast. Bacteria from your skin's surface and baby's mouth can enter the milk ducts through a crack in the skin of your nipple or through a milk duct opening. Stagnant milk in a breast that isn't emptied provides a breeding ground for the bacteria.
Risk factors for mastitis include:
- Previous bout of mastitis while breast-feeding
- Sore or cracked nipples — although mastitis can develop without broken skin
- Wearing a tightfitting bra or putting pressure on your breast when using a seat belt or carrying a heavy bag, which may restrict milk flow
- Improper nursing technique
- Becoming overly tired or stressed
- Poor nutrition
Mastitis that isn't adequately treated or that is due to a blocked duct can cause a collection of pus (abscess) to develop in your breast. An abscess usually requires surgical drainage.
To avoid this complication, talk to your doctor as soon as you develop signs or symptoms of mastitis.
To get your breast-feeding relationship with your infant off to its best start — and to avoid complications such as mastitis — consider meeting with a lactation consultant. A lactation consultant can give you tips and provide invaluable advice for proper breast-feeding techniques.
Minimize your chances of getting mastitis by following these tips:
- Fully drain the milk from your breasts while breast-feeding.
- Allow your baby to completely empty one breast before switching to the other breast during feeding.
- Change the position you use to breast-feed from one feeding to the next.
- Make sure your baby latches on properly during feedings.
- If you smoke, ask your doctor about smoking cessation.
July 22, 2020
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- Lobo RA, et al. Breast diseases: Detection, management, and surveillance of breast disease. In: Comprehensive Gynecology. 7th ed. Philadelphia, Pa.: Elsevier; 2017. https://www.clinicalkey.com. Accessed May 17, 2018.
- Mastitis. La Leche League International. https://www.llli.org/breastfeeding-info/mastitis/. Accessed May 17, 2018.
- Dixon JM. Lactational mastitis. https://www.uptodate.com/contents/search. Accessed May 17, 2018.
- Gabbe SG, et al., eds. Lactation and breastfeeding. In: Obstetrics: Normal and Problem Pregnancies. 7th ed. Philadelphia, Pa.: Elsevier; 2017. https://www.clinicalkey.com. Accessed May 17, 2018.
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