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Puerperal mastitis

Medical Professionals

Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find the Mastitis and breast abscess article more useful, or one of our other health articles.

Mastitis means inflammation of the breast, and may be non-infectious or infectious in origin. In lactating women, it is essentially caused by an accumulation of milk.

Periductal mastitis occurs in 5-9% of non-lactating women worldwide. It is most common in women of reproductive age and is almost exclusively seen in smokers.

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  • Worldwide up to 20% of breastfeeding women develop lactation mastitis1 .

  • The incidence is highest in the first few weeks postpartum, decreasing gradually after that. However, cases may occur as long as the woman is breastfeeding.


Puerperal mastitis may or may not be associated with infection.

  • Non-infectious mastitis is due to an accumulation of milk causing an inflammatory response in the breast.

  • Infectious mastitis occurs when accumulated milk allows bacteria to grow. The usual infecting organism is Staphylococcus aureus, although it may also be Staphylococcus albus and streptococci2 . Meticillin-resistant S. aureus (MRSA) infection is increasing, and may be more common in women who have had a caesarean section.

Infectious mastitis may lead to a breast abscess, which occurs when a localised collection of pus develops.

Risk factors1

  • Problems with attachment of infant to breast during feeding, due to problems with technique or anatomical anomalies such as tongue-tie or cleft lip.

  • Reduced number of feeds, or duration of feeds, leading to milk accumulation. This may be due to:

    • Partial bottle feeding.

    • Changes in regime (due to infant starting to sleep through the whole night for example).

    • Rapid weaning.

    • Painful breasts.

    • Preferred breast, leading to milk accumulation in the other.

  • Pressure on the breast - due to tight clothing, seat belt, sleeping in the prone position.

  • Nipple fissures, cracks and sores.

  • Trauma to breasts.

  • Blocked milk ducts.

NB: evidence for risk factors tends to be of a low research quality.

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Mastitis is diagnosed based on clinical symptoms and signs indicating inflammation - breast pain along with systemic features.


  • This normally presents ≥1 week postpartum, usually in only one breast. The area affected is painful, tender, red and hot.

  • Systemic symptoms include fever, rigors, muscle pain, lethargy, depression, nausea and headache.

  • It should be distinguished from congestive mastitis (breast engorgement) which usually presents on the second or third day of breastfeeding. The complaint in this case is of swollen and tender breasts bilaterally, without fever or erythema.


  • Breast examination reveals unilateral oedema, erythema in a wedge-shaped area, and tenderness. The affected area feels firm and hot.

  • There may be fever.

  • It is not possible to distinguish clinically between infectious and non-infectious mastitis.

  • If a breast abscess has developed, there will be a fluctuant tender lump, with overlying erythema.

  • Axillary lymphadenopathy may be palpable.


Diagnosis is usually clinical. Detection of pathogens in breast milk is not always possible, and the results of milk culture may not be a useful guide for therapy. The agents most frequently identified in milk culture are S. aureus and coagulase-negative Staphylococcus spp. However, these may be contaminants or skin flora. MRSA is increasing in incidence4 . Milk should be cultured if infection is severe or recurrent, or is not starting to resolve after two days of antibiotics, or if infection has been acquired in hospital or severe pain is described as deep/burning5 .

If an abscess is suspected, early referral is required. Ultrasound will show whether there is a collection of pus and should also be considered when infection does not settle after one course of antibiotic.

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First-line management

  • Reassurance. Mastitis is painful, but should not interfere with ability to breastfeed, or affect the long-term appearance of the breast.

  • Encourage the woman to continue breastfeeding. Explain that to do so will not cause any harm to the baby. If it is too painful, consider feeding via expressing until symptoms improve.

  • Improve milk removal. This may involve:

    • Assessment of breastfeeding technique by an appropriately trained, skilled person who can assess feeding pattern, positioning, attachment, sucking behaviour and breast fullness.

    • Manual expression of milk to empty the breast after feeding.

    • Self-massage of the breast before feeding or expression, or application of heat by warm compresses, shower or heat packs.

    • Increasing feeding frequency.

    • Feeding on the affected side first while symptoms persist so this breast is emptied most effectively.

  • Analgesia. Paracetamol or ibuprofen may be used for pain and inflammation where appropriate.

  • Advise not wearing a bra at night.

  • Be aware that many women may require emotional support.

  • Admit if there are signs of sepsis.


Cochrane reviews have found no convincing evidence for the efficacy of antibiotics over first-line management strategies6 . Guidelines such as those by the World Health Organization (WHO) and the Academy of Breastfeeding Medicine suggest first-line measures for 24 hours before starting antibiotics unless the woman is acutely unwell or has an infected nipple injury7 .

Antibiotics, usually flucloxacillin or clarithromycin, should be prescribed5 . Treatment should be in accordance with local prescribing guidelines.

Surgical management

  • Surgical management is indicated for breast abscesses. Incision and drainage of abscess with cavity packed open with gauze is recommended if the overlying skin is thin or necrotic.

  • Parenteral antibiotics should be administered at the same time, with added coverage for anaerobic bacteria. Fluid from the abscess should be cultured, and results used to determine ongoing antibiotic treatment.

  • Needle aspiration of the abscess, repeated every other day until the pus no longer accumulates, has been suggested as an alternative to open drainage.

  • In some cases breastfeeding may have to cease until the abscess is successfully treated, but can usually resume later.

  • Any persisting mass will need further investigation to exclude sinister causes.


A Cochrane review found some evidence that acupoint massage is probably better than routine care, probiotics may be better than placebo, and breast massage and low-frequency pulse treatment may be better than routine care for preventing mastitis. However, they were aware that the evidence presented was incomplete.


Cessation of breastfeeding is the most common complication of mastitis5 . This may lead to emotional distress in women who had planned to continue breastfeeding.

Serious complications occur in cases where treatment is delayed, incorrect or ineffective. These include breast abscess and sepsis. Breast abscesses occur in around 3-7% of women with puerperal mastitis. Stopping breastfeeding suddenly in mastitis increases the risk of developing an abscess. Other risk factors include obesity and smoking.

Further reading and references

  1. Wilson E, Woodd SL, Benova L; Incidence of and Risk Factors for Lactational Mastitis: A Systematic Review. J Hum Lact. 2020 Nov;36(4):673-686. doi: 10.1177/0890334420907898. Epub 2020 Apr 14.
  2. Cullinane M, Amir LH, Donath SM, et al; Determinants of mastitis in women in the CASTLE study: a cohort study. BMC Fam Pract. 2015 Dec 16;16:181. doi: 10.1186/s12875-015-0396-5.
  3. Blackmon MM, Nguyen H, Mukherji P; Acute Mastitis. StatPearls Publishing, 2021.
  4. Parriott AM, Chow AL, Arah OA; Inadequate research on methicillin-resistant Staphylococcus aureus risk among postpartum women. Expert Rev Anti Infect Ther. 2013 Nov;11(11):1127-30. doi: 10.1586/14787210.2013.850027.
  5. Mastitis and breast abscess; NICE CKS, January 2021 (UK access only)
  6. Jahanfar S, Ng CJ, Teng CL; Antibiotics for mastitis in breastfeeding women. Cochrane Database Syst Rev. 2013 Feb 28;2:CD005458. doi: 10.1002/14651858.CD005458.pub3.
  7. Amir LH; ABM clinical protocol #4: Mastitis, revised March 2014. Breastfeed Med. 2014 Jun;9(5):239-43. doi: 10.1089/bfm.2014.9984.
  8. Crepinsek MA, Taylor EA, Michener K, et al; Interventions for preventing mastitis after childbirth. Cochrane Database Syst Rev. 2020 Sep 29;9:CD007239. doi: 10.1002/14651858.CD007239.pub4.

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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