Puerperal Mastitis

Authored by , Reviewed by Dr Hannah Gronow | Last edited | Meets Patient’s editorial guidelines

This article is for 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.

Treatment of almost all medical conditions has been affected by the COVID-19 pandemic. NICE has issued rapid update guidelines in relation to many of these. This guidance is changing frequently. Please visit https://www.nice.org.uk/covid-19 to see if there is temporary guidance issued by NICE in relation to the management of this condition, which may vary from the information given below.

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.

  • Between 10% and 33% of breast-feeding women develop lactation mastitis.[1, 2]
  • The incidence is highest in the first few weeks postpartum, decreasing gradually after that.[3]
  • However, cases may occur as long as the woman is breast-feeding.

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 streptococci. Meticillin-resistant Staphylococcus 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 factors

  • 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.

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 breast-feeding. 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 incidence.[5]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.[1, 6]

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.[3]

First-line management

  • Reassurance. Mastitis is painful, but should not interfere with ability to breast-feed, or affect the long-term appearance of the breast.
  • Encourage the woman to continue breast-feeding. 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 breast-feeding 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.


Cochrane reviews have found no convincing evidence for the efficacy of antibiotics over first-line management strategies.[2]Guidelines such as those by the World Health Organisation (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 injury.

Antibiotics, usually flucloxacillin or erythromycin, should be prescribed. Treatment should be in accordance with local prescribing guidelines.

Surgical management[3]

  • 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 breast-feeding 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.

Cessation of breast-feeding is the most common complication of mastitis.[7]This may lead to emotional distress in women who had planned to continue breast-feeding.[1]

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.[1]Stopping breast-feeding suddenly in mastitis increases the risk of developing an abscess.[6]Other risk factors include obesity and smoking.[9]

Further reading and references

  • Amir LH, Lumley J; Women's experience of lactational mastitis--I have never felt worse. Aust Fam Physician. 2006 Sep35(9):745-7.

  • Schoenfeld EM, McKay MP; Mastitis and methicillin-resistant Staphylococcus aureus (MRSA): the calm before J Emerg Med. 2010 May38(4):e31-4. Epub 2009 Feb 20.

  • Crepinsek MA, Crowe L, Michener K, et al; Interventions for preventing mastitis after childbirth. Cochrane Database Syst Rev. 2012 Oct 1710:CD007239. doi: 10.1002/14651858.CD007239.pub3.

  • Mangesi L, Dowswell T; Treatments for breast engorgement during lactation. Cochrane Database Syst Rev. 2010 Sep 8(9):CD006946. doi: 10.1002/14651858.CD006946.pub2.

  1. Mastitis and breast abscess; NICE CKS, May 2010 (UK access only)

  2. Jahanfar S, Ng CJ, Teng CL; Antibiotics for mastitis in breastfeeding women. Cochrane Database Syst Rev. 2013 Feb 282:CD005458. doi: 10.1002/14651858.CD005458.pub3.

  3. Dixon JM, Khan LR; Treatment of breast infection. BMJ. 2011 Feb 11342:d396. doi: 10.1136/bmj.d396.

  4. Amir LH; Managing common breastfeeding problems in the community. BMJ. 2014 May 12348:g2954. doi: 10.1136/bmj.g2954.

  5. Schoenfeld EM, McKay MP; Mastitis and methicillin-resistant Staphylococcus aureus (MRSA): the calm before J Emerg Med. 2010 May38(4):e31-4. Epub 2009 Feb 20.

  6. Guidelines on the Treatment, Management and Prevention of Mastitis; Guidelines and Audit Implementation Network - GAIN (August 2009)

  7. Spencer JP; Management of mastitis in breastfeeding women. Am Fam Physician. 2008 Sep 1578(6):727-31.

  8. Bharat A, Gao F, Aft RL, et al; Predictors of primary breast abscesses and recurrence. World J Surg. 2009 Dec33(12):2582-6.

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