Mastitis

Mastitis is inflammation (swelling) in the breast, which is usually caused by an infection. It most commonly affects women who are breastfeeding, but can affect other women as well.

A clogged milk duct, not fully draining milk from the breast, or breaks in the skin of the nipple can lead to infection. This causes the body’s white blood cells to release substances to fight the infection, which can lead to swelling and increased blood flow. The infected part of the breast may become swollen, painful, red, and warm to the touch. The woman may also have fever and a headache, or general flu-like symptoms.

Diagnosis

Mastitis can usually be diagnosed based on a woman’s symptoms and the results of a breast exam. It usually affects only one breast.

Treatment

Mastitis is typically treated with antibiotics. In some cases, a breast abscess (a collection of pus) may form. Abscesses are treated by draining the pus, either by surgery or by using a needle (often guided by ultrasound), and then antibiotics. 

Inflammatory breast cancer has symptoms that are a lot like mastitis and can be mistaken for an infection. If you’ve been diagnosed with mastitis and antibiotic treatment doesn’t help within a week or so, you might need a skin biopsy to be sure it’s not cancer. Inflammatory breast cancer can spread quickly, so don’t put off going back to the doctor if you still have symptoms after antibiotic treatment.

How does mastitis affect your risk for breast cancer?

Having mastitis does not raise your risk of developing breast cancer.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Collins LC, Schnitt SJ. Chapter 9: Pathology of benign breast disorders. In: Harris JR, Lippman ME, Morrow M, Osborne CK, eds. Diseases of the Breast. 5th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2014.

Dixon JM, Bundred NJ. Chapter 5: Management of disorders of the ductal system and infections. In: Harris JR, Lippman ME, Morrow M, Osborne CK, eds. Diseases of the Breast. 5th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2014.

Orr B, Kelley JL. Benign breast diseases: Evaluation and management. Clin Obstet Gynecol. 2016;59(4):710-726.

Last Medical Review: September 20, 2017 Last Revised: September 20, 2017

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