What Is a Breast Infection?
A breast infection, also known as mastitis, is an infection that
occurs within the tissue of the breast. Breast infections are most common among
women who are breastfeeding, when the nipples become cracked and sore, allowing
bacteria from a baby’s mouth to enter the breast. This is also known as
lactation mastitis. Mastitis also occurs in women who aren’t breastfeeding, but
this is not as common.
Infection typically affects the fatty tissue in the breast,
causing swelling, lumps, and pain. Although most infections are due to
breastfeeding or clogged milk ducts, a small percentage of breast infections
are associated with rare kinds of breast cancer.
What Causes Breast Infections?
The cause of most breast infections is Staphylococcus aureus bacteria, which cause what is commonly
known as a staph infection. Streptococcus agalactiae is the second most
For breastfeeding mothers, a plugged milk duct can cause milk to
back up and an infection to begin. Breastfeeding can cause cracked nipples and
milk duct openings. If this happens, bacteria from the baby’s mouth can enter and
cause an infection. The bacteria that typically cause infection are normally
found on the skin, even when no infection is taking place. If the bacteria get
into the breast tissue, they can multiply very fast and cause painful symptoms.
You can continue to breastfeed even when you have a mastitis
infection because the bacteria are not harmful to your baby. This condition
usually occurs in the first few weeks of breastfeeding, but it can occur later.
Non-lactational mastitis occurs in women with weakened immune
systems, including women who have had lumpectomies with radiation therapy and
women with diabetes. Some infection-like symptoms are a sign of inflammatory
breast cancer, but this is very rare.
Subareolar abscesses occur when the glands under the nipple
become blocked and an infection develops under the skin. This can form a hard,
pus-filled lump that may need to be drained. This type of abscess normally only
occurs in non-lactating women, and there are no known risk factors for it.
What Are the Symptoms of Breast Infection?
Symptoms of a breast infection can start suddenly and may
- abnormal swelling, leading to one breast becoming
larger than the other
- breast tenderness
- pain or burning while breastfeeding
- a painful lump in the breast
- warm breast
- nipple discharge that contains pus
- skin redness in a wedge-shaped pattern
- enlarged lymph nodes in the armpits or neck
- fever over 101ºF, or 38.3
- feeling ill or rundown
You may experience flu-like symptoms prior to noticing any
changes in your breasts. Contact your doctor if you have any combination of
Inflammatory Breast Cancer
Symptoms of a breast infection may also be associated with
inflammatory breast cancer, which is a rare but serious disease. This type of
cancer begins when abnormal cells in the breast ducts divide and multiply quickly.
These abnormal cells then clog the lymphatic vessels (part of the lymphatic
system, which helps remove waste and toxins from the body) in the skin of the
breast, causing red, swollen skin that is warm and painful to the touch. Breast
changes may occur over the course of several weeks.
Symptoms of inflammatory breast cancer may include:
- thickness or visible enlargement of one breast
- unusual warmth in the affected breast
- discoloration of the breast, making it appear
bruised, purple, or red
- tenderness and pain
- dimpling of the skin, similar to orange peel
- enlarged lymph nodes under the arm or near the
Unlike other forms of breast cancer, women with inflammatory
breast cancer do not develop lumps in the breast. This condition is often
confused with a breast infection. Contact your doctor if you experience any of
How Is a Breast Infection Diagnosed?
In a breastfeeding woman, a doctor can typically diagnose
mastitis based on a physical examination and a review of your symptoms. Your
doctor will also want to rule out whether the infection has formed an abscess
that needs to be drained, which can be done during the physical exam.
If the infection keeps coming back, breast milk may be sent to a
laboratory to determine what bacteria might be present.
Other tests may be necessary to determine the cause if you have a
breast infection and you are not breastfeeding. Testing may include a mammogram
or even a biopsy of breast tissue to rule out breast cancer. A mammogram is an
imaging test that uses low energy X-rays to examine the breast. A breast biopsy
involves the removal of a small tissue sample from the breast for lab testing
to determine if any cancerous cell changes are present.
What Treatments Are Available for Breast Infections?
A 10- to 14-day course of antibiotics is generally the most
effective form of treatment for this type of infection, and most women feel
relief within 48 to 72 hours. It’s important to take all medication as
prescribed to make sure the infection doesn’t happen again. You can continue to
breastfeed while on most antibiotics, but if nursing is uncomfortable, you can use
a breast pump to relieve engorgement and prevent a loss of milk supply.
If you have an abscess due to a severe infection, it may need to
be lanced (clinical incision) and drained. You may have to stop breastfeeding
temporarily if you have an abscess.
If your doctor determines that inflammatory breast cancer is
causing your symptoms, they will begin treatment based on the stage (severity)
of your cancer. Treatment typically involves chemotherapy (using chemicals
intravenously to kill cancer cells), radiation therapy (using high-powered
X-rays to kill cancer cells), or surgery to remove the breast and surrounding
While receiving treatment for infection, you can also take steps
to relieve uncomfortable symptoms at home:
- Warm compresses may ease pain and help
lactation. Try applying a warm, wet washcloth to the infected area for 15
minutes, four times a day.
- Anti-inflammatory medications, such as
ibuprofen, may help relieve pain.
- Use varied positions to breastfeed.
- If possible, avoid prolonged engorgement before
Meeting with a lactation consultant to alter your breastfeeding
technique or position may help prevent the infection from returning.
What Is the Long-Term Outlook for Breast Infection?
Antibiotics are very effective in treating an infection. You’ll
probably feel better within two days, but it’s important to finish the entire
course of antibiotics.
With diligent self-care and adherence to your doctor’s
directions, you can reduce your risk of a recurrence.