ExitCare ImageMastitis is a bacterial infection of the breast tissue.


Bacteria causes infection by entering the breast tissue through cuts or openings in the skin. Typically, this occurs with breastfeeding due to cracked or irritated skin. It can be associated with plugged ducts. Nipple piercing can also lead to mastitis.


In mastitis, an area of the breast becomes swollen, red, tender, and painful. You may notice you have a fever and swelling of the glands under your arm on that side. If the infection is allowed to progress, a collection of pus (abscess) may develop.


Your caregiver can diagnose mastitis based on your symptoms and upon examination. The diagnosis can be confirmed if pus can be expressed from the breast. This pus can be examined in the lab to determine which bacteria are present. If an abscess has developed, the fluid in the abscess can be removed with a needle. This is used to confirm the diagnosis and determine the bacteria present. In most cases, pus will not be present. Blood tests can be done to determine if your body is fighting a bacterial infection. Sometimes, a mammogram or ultrasound will be recommended to exclude other breast diseases including cancer.

Other rare forms of mastitis:

  • Tuberculosis mastitis is rare. The TB germ can affect the breast if it is present in some other part of the body. The breast may be slightly tender with a mass, but not tender or painful.

  • Syphilis of the nipple usually has an ulcer that is not tender.

  • Actinomycosis is a very rare bacterial infection of the breast that presents as a mass in the breast that is not tender or painful.

  • Phlebitis (inflammation of blood vessels) of the breast is an inflammation of the veins in the breast. It may be caused by tight fitting bras, surgery, or trauma to the breast.

  • Inflammatory carcinoma of the breast looks like mastitis because the breasts are red, swollen, or tender, but it is a rare form of breast cancer.


Antibiotic medication is used to treat the bacterial infection. Your caregiver will determine which bacteria are most likely to be causing the infection and select an antibiotic. This is sometimes changed based on the results of cultures, or if there is no response to the antibiotic selected. Antibiotics are usually given by mouth. If you are breastfeeding, it is important to continue to empty the breast. Your caregiver can tell you whether or not this milk is safe for your infant, or needs to be thrown away. Pain can usually be treated with medication.


  • Take your antibiotics as directed. Finish them even if you start to feel better.

  • Only take over-the-counter or prescription medication for pain, discomfort, or fever as directed by your caregiver.

  • If breastfeeding, keep your nipples clean and dry. Your caregiver may tell you to stop nursing until he or she feels it is safe for your baby. Use a breast pump as instructed if forced to stop nursing.

  • Do not wear a tight bra. Wear a good support bra.

  • Empty the first breast completely before going to the other breast. If your baby is not emptying your breasts completely for some reason, use a breast pump to empty your breasts.

  • If you go back to work, pump your breasts while at work to stay in time with your nursing schedule.

  • Increase your fluid intake especially if you have a fever.

  • Avoid having your breasts get overly filled with milk (engorged).


  • You develop pus-like (purulent) discharge from the breast.

  • Your symptoms get worse.

  • You do not seem to be responding to your treatment within 2 days.


  • You have a fever.

  • Your pain and swelling is getting worse.

  • You develop pain that is not controlled with medicine.

  • You develop a red line extending from the breast toward your armpit.