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    Breast Infection: from Symptoms to Treatments

    Updated 16 January 2019 |
    Published 02 January 2019
    Fact Checked
    Reviewed by Dr. Anna Klepchukova, Intensive care medicine specialist, chief medical officer, Flo Health Inc., UK
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    A breast infection, or also known as mastitis, is a regional infection of the breast. It is commonly caused by the woman’s skin flora or the oral flora of breastfeeding infants. A breast infection is a condition most typical of breastfeeding women: bacteria from a baby’s mouth enter an erosion or cracked nipple and infects the breasts.

    The fatty tissue of the breast is typically affected, and it causes swelling and lump in breasts that hurt. Most of the breast infections are connected with breastfeeding or clogged milk ducts, but still, there is a small percentage of breast infection associated with some rarer types of breast cancer. So, there are two types of mastitis: lactational and non-lactational mastitis.

    How the breast is built?

    The main building parts of the female breast are nipple, lactiferous sinus, lobules, ducts, and stroma. The lobules are glands that are producing the milk. After being produced, the milk passes through the ducts. The ducts connect the lobules and the nipple. Stroma represents a fatty tissue that surrounds the ducts and lobules, lymphatic and blood vessels.

    An adult woman has around 20 lobes in each breast. One lobe is built from 20 to 50 lobules. The ducts are attached to the lobules. Smaller ducts join together into the increasingly larger duct. Each breast has around 10 ducts systems, and each duct has its own popping at the nipple.

    There is also muscle tissue present in the nipples. The muscle tissue allows the nipples to become erect in response to stimulation or breastfeeding. With the help of the muscle tissue found around the lobules, the milk is squeezed into the ducts.

    Some women have inverted nipples. In most of the cases, having an inverted nipple won’t affect you. Sometimes, breast changes can be a sign of pregnancy.

    What are the most common medical conditions affecting the breast?

    Inflammatory breast cancer is one of the most common medical conditions affecting the breast. This type of cancer occurs when abnormal cells found in the breast start to divide and multiply quickly and without control. These abnormal cells then clog the lymphatic vessels that are part of the lymphatic system which is responsible to remove waste and toxins from the body. Clogging the lymphatic vessels in the skin of the breast causes red and swollen skin that is often painful to the touch. It may take even up to several weeks for the breast changes to occur.

    Symptoms of inflammatory breast cancer are:

    • Feeling unusual warmth in the affected breast
    • Tenderness and pain. Sometimes, this can be a sign of ovulation as well.
    • Visible enlargement of one of the breasts
    • Enlarged lymph nodes found in the armpit area
    • Discoloration of the breast. The breast may be purple or red. 

    What causes breast infection?

    Bacteria called Staphylococcus aureus is the cause of most breast infections. This bacterium causes what is mainly known as a staph infection. Apart from Staphylococcus aureus, the second most common cause is Staphylococcus agalactiae.

    In women that are breastfeeding, a blocked milk duct can back up the milk and infection may occur. Having cracked nipples and nipple infection also increases the chances of getting a breast infection. When breastfeeding your baby, the bacteria enters from the baby's mouth and causes infection. These bacteria are usually found on the skin. You may even have the bacteria present on your skin, but still, there may be no infection taking place. When the bacteria enter into the breast tissue, it has the power to multiply quickly and cause painful symptoms.

    Women having a weakened immune system can also get a breast infection. This includes women who have had lumpectomies with radiation therapy and women that have diabetes.

    When the glands under the infected nipple become blocked, subareolar abscesses occur. In this way, the bacteria can develop under the skin. This forms a hard lump that needs to be drained. Subareolar abscesses happen mainly in nonlactating women.

    Symptoms of a breast infection

    For lactational mastitis the symptoms are usually unilateral and appear 2-4 weeks postpartum. They include:

    • Diffusely tender, and firm breasts particularly at the time of engorgement or milk letdown
    • Warm breast
    • Palpable mass
    • Pain or burning sensation while breastfeeding. 

    Non-lactational mastitis symptoms: 

    • Focal tenderness
    • Erythema
    • Differences in temperature from one region of the breast to another.

    Sometimes, there may be only symptoms of a flu present, and you won't be able to notice any changes in the breast. If you have any combination of the symptoms stated above, contact your doctor.

    When to seek medical treatment?

    You should call your doctor immediately if you feel any limp. It doesn’t matter if you are breastfeeding or not. Also, contact your health provider in case you:

    • Notice any symptoms that are related to a breast infection. This includes redness, swelling, painful lump in the breast or pain that disturbs with breastfeeding.
    • If you have unexplained breast pain that doesn’t go away, and it makes it difficult for you to function during the day.
    • If you have abnormal discharge from your nipples.
    • If you have a yeast infection under the breast, ask your doctor how to treat yeast infection under the breast.

    How a breast infection is diagnosed?

    Doctors can easily diagnose breast infection in women that are breastfeeding. They can diagnose it based on a physical examination and a review of the symptoms like fever, and an elevated WBC (white blood cell count).

    After that, the doctor should define whether the cause of the infection is the formation of an abscess that needs to be drained. This can be done during a physical exam.

    If the breast infection occurs again, a sample of the breast milk will be sent to a laboratory to determine whether there is a bacteria present.

    If you are not breastfeeding, another type of test will be done to determine the cause of the infection.  You will be asked to do a mammogram (imaging test based on a low-energy X-rays) or biopsy of breast tissue (a small sample tissue will be removed from the breast for laboratory examinations) in order to rule out the breast cancer.

    What treatments are available?

    The most common and effective form of treatment is a two-week course of PO antibiotics (like dicloxacillin, cephalexin, amoxicillin/clavulanate, azithromycin, clindamycin).

    Women who are unresponsive to oral antibiotics are admitted for IV antibiotics until afebrile for 48 hours.

    Most of the women feel improvement within 2 to 3 days (48-72 hours). It is necessary to take all of the medicine as prescribed by your doctor. If you are breastfeeding, you can continue to feed your baby or use a breast pump if you are not breastfeeding. These antibiotics for breast infection don’t cause any damage to your milk or to your baby.  If no improvement within 48-72 hours, you should be administered to the ultrasonography to asses for abscess. In case you have abscess, treat with incision and drainage.

    If the doctor determines that the cause of the breast infection is inflammatory breast cancer, you will have to start a treatment that involves chemotherapy, radiation therapy or surgery.

    How can I care for breast infections at home?

    You can try and treat your breast infection at home as well.

    • If you are having pain, take acetaminophen like Tylenol and Ibuprofen for pain. These are safe medicines for women that are breastfeeding a baby. If your pain is severe, you should see your doctor. He or she will prescribe you a stronger pain reliever.
    • Sometimes, antibiotics may not be prescribed at all. But if your doctor has prescribed you some medicines, finish the entire course of medication. It is really important to do that, even if you feel better.
    •  Don’t stop breastfeeding your baby from the affected breast. It doesn’t matter whether you feel pain the right breast or in the left one. It can be painful, but you must continue to breastfeed. Often emptying of the breast prevents engorgement and clogged ducts that can only make the infection worse.
    • Use a pump to empty the breast, in case it is too painful for you to breastfeed on the infected breast.
    • Don’t worry whether the infection can cause harm to the baby. Most probably the source of the bacteria was your baby’s mouth.
    • Stay hydrated. Drink plenty of water. Balance your meals and add 500 more calories a day while breastfeeding. Dehydration and poor nutrition can decrease milk supply.

    How can I prevent breast infections?

    You are breastfeeding your baby, here are some tips that will help you reduce the chances of having a breast infection:

    • Try to empty at least one breast while feeding each time. Use clips if you can't remember which breast was last.
    • Learn about the alarming postpartum symptoms .
    • Don't get nervous or stressed if you're late or feeding.
    • Try to follow a certain schedule for feeding.
    • Don't use soap or other chemical product for cleaning the nipple. Remember that the areola has the self-cleaning ability and lubricates by itself.
    • Add saturated fat in your daily diet in order to help reduce the risk of developing reoccurring plugged ducts.
    • Massage your breasts, especially if you are feeling a painful breast lump.
    • Try different positions for breastfeeding your baby. The baby is most efficient at draining ducts while being in the direction where the chin is pointing.
    • Put a warm and wet towel when you're breastfeeding to increase the flow of the milk.
    • Don't wear tight fitting bras. They can dig in and impede natural milk flow.


    Mastitis is a common issue among women. If you have a breast infection and follow all of the recommendations from your doctor, you will probably get better soon. By listening to the doctor’s advice, you can reduce your chances of getting breast infection as well.

    History of updates

    Current version (16 January 2019)

    Reviewed by Dr. Anna Klepchukova, Intensive care medicine specialist, chief medical officer, Flo Health Inc., UK

    Published (02 January 2019)

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