Breast Infection

Medically Reviewed by Mahammad Juber, MD on December 10, 2022
Written by WebMD Editorial Contributors
8 min read

The breast is composed of several glands and ducts that lead to the nipple and the surrounding colored area called the areola. The milk-carrying ducts extend from the nipple into the underlying breast tissue like the spokes of a wheel. Under the areola are lactiferous ducts. These fill with milk during lactation after a woman has a baby. When a girl reaches puberty, changing hormones cause the ducts to grow and cause fat deposits in the breast tissue to increase. The glands that produce milk (mammary glands) that are connected to the surface of the breast by the lactiferous ducts may extend to the armpit area.

 

Mastitis is an infection of the tissue of the breast that occurs most frequently during the time of breastfeeding. It can occur when bacteria, often from the baby's mouth, enter a milk duct through a crack in the nipple.

Breast infections most commonly occur one to three months after the delivery of a baby, but they can occur in women who have not recently delivered and in women after menopause. Other causes of infection include chronic mastitis and a rare form of cancer called inflammatory carcinoma.

In healthy women, mastitis is rare. However, women with diabetes, chronic illness, AIDS, or an impaired immune system may be more susceptible.

About 1%-3% of breastfeeding mothers develop mastitis. Engorgement and incomplete breast emptying can contribute to the problem and make the symptoms worse.

Chronic mastitis occurs in women who are not breastfeeding. In postmenopausal women, breast infections may be associated with chronic inflammation of the ducts below the nipple. Hormonal changes in the body can cause the milk ducts to become clogged with dead skin cells and debris. These clogged ducts make the breast more open to bacterial infection. Infection tends to come back after treatment with antibiotics.

Breast infections may cause pain, redness, and warmth of the breast along with the following symptoms:

  • Tenderness and swelling
  • Body aches
  • Fatigue
  • Breast engorgement
  • Fever and chills
  • Abscess: A breast abscess can be a complication of mastitis. Noncancerous masses such as abscesses are more often tender and frequently feel mobile beneath the skin. The edge of the mass is usually regular and well defined. Indications that this more serious infection has occurred include the following:
    • Tender lump in the breast that does not get smaller after breastfeeding a newborn (If the abscess is deep in the breast, you may not be able to feel it.)
    • Pus draining from the nipple
    • Persistent fever and no improvement of symptoms within 48-72 hours of treatment

Call your health care provider as soon as you feel any suspicious lump, whether you are breastfeeding or not. Call for an appointment if:

  • You have any abnormal discharge from your nipples.
  • Breast pain is making it difficult for you to function each day.
  • You have prolonged, unexplained breast pain.
  • You have any other associated symptoms such as redness, swelling, pain that interferes with breastfeeding, a mass or tender lump in the breast that does not disappear after breastfeeding.
  • If you are breastfeeding, call your doctor if you develop any symptoms of breast infection so that treatment may be started promptly.

You may need to be evaluated in a hospital's emergency department if the breast pain is associated with other signs of an infection (such as a fever, swelling, or redness to the breast) and if your health care provider cannot see you promptly. The below symptoms require emergency treatment:

  • A persistent high fever greater than 101.5°F
  • Nausea or vomiting that is preventing you from taking the antibiotics as prescribed
  • Pus draining from the breast
  • Red streaks extending toward your arm or chest
  • Dizziness, fainting, or confusion

The diagnosis of mastitis and a breast abscess can usually be made based on a physical exam.

  • If it is unclear whether a mass is due to a fluid-filled abscess or to a solid mass such as a tumor, a test such as an ultrasound may be done. An ultrasound may also be helpful in distinguishing between simple mastitis and abscess or in diagnosing an abscess deep in the breast. This noninvasive test allows your doctor to directly visualize the abscess by placing an ultrasound probe over your breast. If an abscess is confirmed, aspiration or surgical drainage, and IV antibiotics, are often required.
  • Cultures may be taken, either of breast milk or of material taken out of an abscess through a syringe, to determine the type of organism causing the infection. This information can help your doctor decide what kind of antibiotic to use.
  • Nonbreastfeeding women with mastitis, or those who do not respond to treatment, may have a mammogram or breast biopsy. This is a precautionary measure because a rare type of breast cancer can produce symptoms of mastitis.

 

Breast infections require treatment by a health care provider.

After you see a doctor, try the following to help your breast infection heal.

  • Pain medication: Take acetaminophen (Tylenol) or ibuprofen (such as Advil) for pain. These drugs are safe while breastfeeding and will not harm your baby. Your doctor may prescribe a prescription strength pain reliever if your pain is severe and not relieved with over-the-counter medication.
  • In mild cases of mastitis, antibiotics may not be prescribed at all. If you are prescribed antibiotics, finishing the prescription even if you feel better in a few days is very important.
  • Frequent feedings: Do not stop breastfeeding from the affected breast, even though it will be painful and you may be taking antibiotics. Frequent emptying of the breast prevents engorgement and clogged ducts that can only make mastitis worse.
    • If needed, use a breast pump to relieve pressure and completely empty the breast.
    • You can also breastfeed from the unaffected side and supplement with infant formula as needed.
    • The infection will not harm the baby because the germs that caused the infection probably came from the baby’s mouth in the first place.
    • Breastfeeding should be avoided in the infected breast when an abscess is present.
  • Pain relief: A warm compress applied before and after feedings can often provide some relief. A warm bath may work as well.
    • If heat is ineffective, ice packs applied after feedings may provide some comfort and relief.
    • Avoid using ice packs just before breastfeeding because it can slow down milk flow.
    • Drink plenty of water -- at least 10 glasses a day. Eat well-balanced meals and add 500 extra calories a day while breastfeeding. Dehydration and poor nutrition can decrease milk supply and make you feel worse.

For simple mastitis without an abscess, oral antibiotics are prescribed. Cephalexin (Keflex) and dicloxacillin (Dycill) are two of the most common antibiotics chosen, but a number of others are available. The antibiotic prescribed will depend on your specific situation, your doctor’s preference, and any drug allergies you may have. This medicine is safe to use while breastfeeding and will not harm the baby.

Chronic mastitis in nonbreastfeeding women can be complicated. Recurrent episodes of mastitis are common. Occasionally, this type of infection responds poorly to antibiotics. Therefore, close follow-up with your doctor is mandatory.

If the infection worsens in spite of oral antibiotics or if you have a deep abscess requiring surgical treatment, you may be admitted to the hospital for IV antibiotics.

If an abscess is present, it must be drained. After injection of a local anesthetic, the doctor may drain an abscess near the surface of the skin either by aspiration with a needle and syringe or by using a small incision. This can be done in the doctor’s office or emergency department.

If the abscess is deep in the breast, however, it may require surgical drainage in the operating room. This procedure is usually done under general anesthesia to minimize pain and completely drain the abscess. Antibiotics and heat on the area are also used to treat abscesses.

Mastitis does not cause cancer, but cancer can mimic mastitis in appearance. If a breast infection is slow to go away, your health care provider may recommend a mammogram or other tests to rule out cancer.

If you have a breast infection, you may be seen for a recheck in 24-48 hours.

  • Take all antibiotics as prescribed.
  • Take your temperature three times a day for the first 48 hours after treatment begins. Watch for fever.
  • Call your doctor if you develop a high fever, vomiting, or increasing redness, swelling, or pain in the breast.
  • Follow up with your doctor in one to two weeks to make sure that the infection has gone away. If the infection spreads or an abscess develops, you may require IV antibiotics or surgical treatment.

Sometimes mastitis is unavoidable. Some women are more susceptible than others, especially those who are breastfeeding for the first time. In general, good habits to prevent mastitis include the following:

  • Breastfeed equally from both breasts.
  • Empty breasts completely to prevent engorgement and blocked ducts.
  • Use good breastfeeding techniques to prevent sore, cracked nipples.
  • Allow sore or cracked nipples to air dry.
  • Prevent moisture from accumulating in breast pads or bras.
  • Avoid dehydration by drinking plenty of fluids.
  • Practice careful hygiene: Handwashing, cleaning the nipples, keeping your baby clean.

When treated promptly, the majority of breast infections go away quickly and without serious complications. Most women can and should continue to breastfeed despite an episode of uncomplicated mastitis. With proper treatment, symptoms should begin to resolve within one to two days.

A breast abscess may require surgical drainage, IV antibiotics, and a short hospital stay. A small incision is made and usually heals quite well. Prognosis for complete recovery is also good.

Postmenopausal women with breast abscesses have a high rate of return after simple drainage and frequently need to follow up with a surgeon for more definitive treatment. Chronic infection can result if an abscess is not completely drained, and this can result in a poor cosmetic outcome.