Last updated: November 21, 2022

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Mastitis is inflammation of the breast tissue and most commonly affects individuals who are lactating (puerperal mastitis). Nonlactional mastitis, although rare, can also occur. Mastitis typically manifests as pain, swelling, and redness of the affected breast(s) with or without systemic signs of infection. Diagnosis is usually clinical; studies such as breast milk culture and imaging may be indicated to rule out complications (e.g., breast abscess) and differential diagnoses (e.g., inflammatory breast cancer). Puerperal mastitis may resolve with supportive therapy. Patients with severe or persistent symptoms should additionally receive empiric antibiotics.

Mastitis is defined as inflammation of the breast, with or without infection. [1][2]

  • Puerperal mastitis: mastitis associated with lactation
  • Nonpuerperal mastitis:
    • Mastitis not associated with lactation
    • May affect subareolar ducts (periareolar or periductal mastitis) or peripheral parenchyma
    • Idiopathic granulomatous mastitis (rare): recurrent or persistent mastitis, often associated with a palpable mass; most commonly affects parous women [2][3]

Epidemiological data refers to the US, unless otherwise specified.

Infectious mastitis [2]

Noninfectious mastitis

  • Nipple fissures facilitate the entry of bacteria located in the nostril and throat of the infant or on the skin of the mother into the milk ducts during breastfeeding.
  • Prolonged breast engorgement; (due to overproduction of milk ) or insufficient drainage of milk; (e.g., due to infrequent feeding, quick weaning, illness in either the baby or mother) result in milk stasis, which creates favorable conditions for bacterial growth within the lactiferous ducts.

Inflammatory breast cancer may manifest with features similar to mastitis and should be evaluated for in patients with inadequate response to empiric treatment of mastitis. [1]

  • Diagnosis is usually clinical.
  • Diagnostic studies are indicated to evaluate for complications or alternative diagnoses in patients with atypical presentation or poor response to initial empiric antibiotic therapy.

Breast milk culture [2][4][7]



Imaging [1]

Indications (not routinely required) [4][7]


Supportive findings (of mastitis) [3]

Mammography is not contraindicated during lactation. Nursing or expressing breast milk before imaging improves imaging sensitivity. [11]


Puerperal mastitis [1][4][13]

  • Initiate supportive therapy.
  • Consider antibiotics if no improvement after 12–24 hours. [7][13]
  • For inadequate response to initial treatment or recurrence of symptoms, consider:
  • Severe cases (e.g., sepsis): Admit to hospital and initiate IV antibiotics.

Supportive therapy [4][13]

Patients with mastitis should continue breastfeeding to reduce the risk of a breast abscess, but feeding should only be on-demand to avoid contributing to the inflammatory process. [7]

Empiric antibiotic therapy for breast infections

Avoid TMP-SMX in lactating mothers with newborns < 30 days old because of the risk of kernicterus. [7]

Nonpuerperal mastitis [1][2][6]

  • Anticipatory lactational counseling [14]
  • To prevent recurrence: Consider oral Lactobacillus probiotic. [7][15]
  1. ACOG. Practice Bulletin No. 164 Diagnosis and management of benign breast disorders. Obstetrics & Gynecology. 2016; 127 (6): p.e141-e156. doi: 10.1097/aog.0000000000001482 . | Open in Read by QxMD
  2. Boakes E, Woods A, et al. Breast Infection: A Review of Diagnosis and Management Practices. Eur J Breast Health. 2018 . doi: 10.5152/ejbh.2018.3871 . | Open in Read by QxMD
  3. Guirguis MS, Adrada B, Santiago L, Candelaria R, Arribas E. Mimickers of breast malignancy: imaging findings, pathologic concordance and clinical management. Insights Imaging. 2021; 12 (1). doi: 10.1186/s13244-021-00991-x . | Open in Read by QxMD
  4. Spencer JP. Management of mastitis in breastfeeding women. Am Fam Physician. 2008; 78 (6): p.727-731.
  5. Kasales CJ, Han B, Smith JS, Chetlen AL, Kaneda HJ, Shereef S. Nonpuerperal Mastitis and Subareolar Abscess of the Breast. AJR Am J Roentgenol. 2014; 202 (2): p.W133-W139. doi: 10.2214/ajr.13.10551 . | Open in Read by QxMD
  6. Pluguez-Turull CW, Nanyes JE, Quintero CJ, et al. Idiopathic Granulomatous Mastitis: Manifestations at Multimodality Imaging and Pitfalls. RadioGraphics. 2018; 38 (2): p.330-356. doi: 10.1148/rg.2018170095 . | Open in Read by QxMD
  7. Mitchell KB, Johnson HM, Rodríguez JM, et al. Academy of Breastfeeding Medicine Clinical Protocol #36: The Mastitis Spectrum, Revised 2022. Breastfeed Med. 2022; 17 (5): p.360-376. doi: 10.1089/bfm.2022.29207.kbm . | Open in Read by QxMD
  8. Berens P, Eglash A, Malloy M, Steube AM. ABM Clinical Protocol #26: Persistent Pain with Breastfeeding. Breastfeed Med. 2016; 11 (2): p.46-53. doi: 10.1089/bfm.2016.29002.pjb . | Open in Read by QxMD
  9. Moy L, Heller SL, Bailey L, et al. ACR Appropriateness Criteria ® Palpable Breast Masses. J Am Coll Radiol. 2017; 14 (5): p.S203-S224. doi: 10.1016/j.jacr.2017.02.033 . | Open in Read by QxMD
  10. Trop I, Dugas A, David J, et al. Breast Abscesses: Evidence-based Algorithms for Diagnosis, Management, and Follow-up. RadioGraphics. 2011; 31 (6): p.1683-1699. doi: 10.1148/rg.316115521 . | Open in Read by QxMD
  11. diFlorio-Alexander RM, Slanetz PJ, Moy L, et al. ACR Appropriateness Criteria® Breast Imaging of Pregnant and Lactating Women. J Am Coll Radiol. 2018; 15 (11): p.S263-S275. doi: 10.1016/j.jacr.2018.09.013 . | Open in Read by QxMD
  12. Mitchell KB, Johnson HM, Eglash A, et al. ABM Clinical Protocol #30: Breast Masses, Breast Complaints, and Diagnostic Breast Imaging in the Lactating Woman. Breastfeed Med. 2019; 14 (4): p.208-214. doi: 10.1089/bfm.2019.29124.kjm . | Open in Read by QxMD
  13. Khan TV, Ramirez M. Management of Common Breastfeeding Problems. Clinical Lactation. 2017; 8 (4): p.181-188. doi: 10.1891/2158-0782.8.4.181 . | Open in Read by QxMD
  14. Niazi A, Rahimi VB, Soheili-Far S, et al. A Systematic Review on Prevention and Treatment of Nipple Pain and Fissure: Are They Curable?. Journal of pharmacopuncture. 2018; 21 (3): p.139-150. doi: 10.3831/KPI.2018.21.017 . | Open in Read by QxMD
  15. Fernández L, Cárdenas N, Arroyo R, et al. Prevention of Infectious Mastitis by Oral Administration ofLactobacillus salivariusPS2 During Late Pregnancy. Clinical Infectious Diseases. 2015; 62 (5): p.568-573. doi: 10.1093/cid/civ974 . | Open in Read by QxMD

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