What Is Mastitis?

Breast swelling can be caused by an infection or clogged duct while nursing

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When you’ve just given birth and started to breastfeed, the sleep deprivation and demands of a growing baby are exhausting enough—and then there’s mastitis. Characterized by debilitating fatigue and breast pain, mastitis refers to inflammation, swelling, or a lump in the breast often caused by an infection or blocked milk duct.

While mastitis can happen at any time during breastfeeding, it most commonly occurs within the first two months of giving birth. Mastitis develops in 1 in 5 new mothers, and about 1 in 10 experience recurring bouts of the condition, according to a 2015 study published in BMC Family Practice.

Baby breastfeeding

KIYOKO FUKUDA / a.collectionRF / Getty Images

Any change in breast health can be concerning, and even more so when your baby is relying on you for nutrition. Sometimes mastitis can clear with rest and self-care in a day or two. But if not, you may need to see a healthcare provider for a diagnosis and treatment, which can include prescription medication.

Wondering if you should give your healthcare professional a call? Learn about the signs of mastitis, what causes it, when to ask for help, how to cope, and more. 

Signs and Symptoms of Mastitis

Mastitis may cause: 

  • Breast pain, warmth, or tenderness 
  • Swelling and redness in the affected area
  • Fever 
  • Chills 
  • Flu-like symptoms such as fatigue or body aches 
  • Nausea or vomiting 
  • Yellowish nipple discharge

Contact your healthcare provider if you have a fever or your symptoms worsen over the next 24 hours. 

Seek help immediately if you experience any of the following:

  • Your symptoms are sudden and severe
  • Both breasts seem to be infected
  • Your breast milk appears to have pus or blood in it
  • There are red streaks on your skin around the affected part of your breast


In most cases, mastitis is caused by an infection from bacteria found on the skin. When your nipples are cracked or injured, that bacteria can enter your body and cause an infection.

Another common culprit is chronically engorged breasts or plugged milk ducts due to breastfeeding challenges, weaning, or an overabundant supply of breast milk. If you’re struggling to drain breast milk, your breast could become prime territory for an infection.

Risk Factors 

Many factors can increase your risk of developing mastitis, such as:

  • Nipple pain, cracked nipples, nipple damage
  • Oversupply of breast milk
  • Use of a nipple shield
  • Expressing milk several times a day 
  • Engorgement
  • Disrupted milk flow due to an overly restrictive, tight-fitting bra, or pressure from the strap of a sling, bag, or seat belt
  • Difficulties with your baby latching onto your nipple or breastfeeding


If you suspect you may have mastitis, contact your healthcare professional to schedule an appointment. During your meeting, they’ll ask you about your symptoms and examine your breasts in order to come up with a diagnosis.

In some cases, such as recurrent mastitis, you may need additional tests like a breast milk culture, which can be taken with a small breast milk sample from your affected side.

With this and other tests, your healthcare provider can determine the exact cause of your infection to ensure you’re given the best antibiotics to treat it or rule out other conditions that may cause similar symptoms.


To treat mastitis, your healthcare provider may prescribe an antibiotic that’s safe to take while breastfeeding, such as dicloxacillin, cephalexin, clindamycin, or erythromycin. You’ll also need to empty your breast regularly. 

If initial treatment is ineffective or the infection worsens, you could develop a breast abscess or collection of pus. This can be treated by draining the pus via surgery or a needle guided by ultrasound, followed by antibiotics.

Inflammatory breast cancer, a rare type of breast cancer that spreads rapidly, can cause symptoms that resemble mastitis such as breast swelling, purple or red skin, and an orange peel-like dimpling of the skin.

If antibiotic treatment does not help your mastitis clear within a week or so, don’t delay. Contact your healthcare provider to schedule another exam to ensure it’s not cancer and to avoid a worsening infection.


It’s totally understandable if all you want to do is stop breastfeeding when you’re feeling run down and your breast hurts. Mastitis can be life-disrupting during an already challenging time, and many people say it makes it difficult to get through day-to-day tasks, let alone breastfeed.

However, it’s essential to continue emptying your breasts as you heal from mastitis. Although your breast milk may change as your body fights an infection, it’s safe for your baby to drink, and keeping milk flowing helps support the recovery process. 

In the meantime, here’s how to cope: 

  • Rest up. Often, mastitis strikes when you’re not getting enough sleep, or you’re stressed out. Ask for others to help so you can get some much-needed sleep and let your body work on healing. Make sure to drink plenty of fluids and eat a healthy diet, too. 
  • Continue breastfeeding. Nurse frequently from both breasts (every two hours or more frequently). If the baby refuses or is unable to drink from the affected breast, hand express or use a breast pump until it’s drained.
  • Practice alternate massage. Each time your baby pauses between sucks, massage and compress your breast and any hard area to encourage your breast to drain.  
  • Use warm and cold compresses. To ease pain and promote milk flow, apply a warm, wet washcloth to your breast for about 15 minutes before feedings at least three times a day. You can use cold packs to relieve pain as well.
  • Consider pain medication. Ask your healthcare professional about taking over-the-counter pain relievers such as nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen to dial down inflammation and discomfort or Tylenol (acetaminophen) for pain or a fever.
  • Finish your antibiotics. Although you may begin to feel better in a day or two, take the full course of antibiotics as prescribed.
  • Treat yourself to some new nursing bras. A well-fitted, supportive bra can help ensure you’re not putting too much pressure on your milk ducts.
  • Connect with a lactation consultant. Mastitis can pop up when you’re not breastfeeding at the proper angle, or your baby is struggling to latch on correctly. In this case, a trained lactation consultant or nurse can help you learn how to address these common problems and reduce your risk of recurring infections.

A Word From Verywell

Mastitis is likely the last thing you want to deal with when you're getting to know your new child and recovering during the postpartum period. But sometimes it can serve as a signal that it's time to prioritize rest and self-care or lean on the expertise of a nurse or lactation consultant.

Remember that you're not alone; there are people who can help. This condition is highly treatable with the right medication and coping skills.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Office on Women’s Health. Common breastfeeding challenges.

  3. Bodine AM, Holahan B, Mixon A. Benign breast conditions. The Journal of the American Osteopathic Association. 2017;117,755-760. doi:10.7556/jaoa.2017.147

  4. Wilson E, Woodd SL, Benova L. Incidence of and risk factors for lactational mastitis: A systematic reviewJ Hum Lact. 2020;36(4):673-686. doi:10.1177/0890334420907898

  5. Cleveland Clinic. Mastitis.

  6. University of Michigan Health System (UMHS). Mastitis while breastfeeding.

  7. American Cancer Society. Breast mastitis.

  8. American Cancer Society. Inflammatory breast cancer.

By Lauren Krouse
Lauren Krouse is a journalist especially interested in covering women’s health, mental health, and social determinants of health. Her work appears in Women's Health, Prevention, and Self, among other publications.