How should I treat a breastfeeding mother with mastitis?

Management of Mastitis in Breastfeeding Women

For a breastfeeding mother with mastitis, initiate a 1-2 day trial of conservative management with NSAIDs, ice application, and continued breastfeeding; if symptoms do not improve within 12-24 hours, start narrow-spectrum antibiotics targeting Staphylococcus aureus, with dicloxacillin 500 mg orally four times daily or cephalexin 500 mg orally four times daily as first-line agents. 1, 2

Initial Conservative Management (First 12-24 Hours)

Most mastitis cases are inflammatory rather than infectious, with 14-20% resolving spontaneously without antibiotics. 2, 3 The initial approach should include:

• Continue breastfeeding or direct feeding from the affected breast – this is crucial for resolution and does not pose risk to the infant. 4, 1, 5
• NSAIDs for pain and inflammation – reduces both symptoms and inflammatory response. 2, 3
• Ice application – helps reduce inflammation and provides symptomatic relief. 2, 3
• Minimize pumping – excessive pumping can worsen mastitis by overstimulating milk production and causing tissue trauma. 3
• Avoid heat application and aggressive breast massage – these practices are no longer recommended as they may worsen the condition. 3

When to Start Antibiotics

Add antibiotics if symptoms do not improve within 12-24 hours of conservative management, as delaying treatment increases the risk of abscess formation, which occurs in approximately 10% of mastitis cases. 4, 2, 5

First-Line Antibiotic Therapy

For Patients Without Penicillin Allergy:

• Dicloxacillin 500 mg orally four times daily for 7 days – preferred first-line agent targeting methicillin-susceptible S. aureus, the predominant pathogen. 1, 2, 5
• Cephalexin 500 mg orally four times daily for 7 days – equally effective alternative, particularly useful for patients with non-severe penicillin allergy. 1, 2, 5

Both agents are safe during breastfeeding with minimal transfer to breast milk. 1, 2

For Penicillin-Allergic Patients:

• Cephalexin 500 mg orally four times daily – can be used in patients with non-immediate (non-IgE-mediated) hypersensitivity to penicillin. 1
• Clindamycin 300-450 mg orally three times daily – option for true penicillin-allergic patients, though it may increase gastrointestinal side effects in the infant. 1, 2
• Erythromycin or azithromycin – acceptable alternatives, but note there is a very low risk of infantile hypertrophic pyloric stenosis if macrolides are used during the first 13 days of infant life; generally considered safe after this period. 1

MRSA Coverage (When Indicated)

Consider MRSA-targeted therapy if: 2

• High local MRSA prevalence
• Previous MRSA infection
• No response to first-line beta-lactam antibiotics within 48-72 hours

MRSA-Targeted Oral Regimens:

• Clindamycin 300-450 mg orally three times daily – if isolate is confirmed clindamycin-susceptible (resistance ranges 3-15%). 1
• Trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 double-strength tablets orally twice daily – provides MRSA coverage but lacks activity against Streptococcus species; add a concurrent beta-lactam if streptococcal infection is possible. 1 Important caveat: Avoid TMP-SMX in infants ≤28 days old, those with jaundice, prematurity, or G6PD deficiency due to risk of bilirubin displacement and hemolytic anemia. 2
• Linezolid 600 mg orally twice daily – alternative MRSA-active agent, though expensive and bacteriostatic. 1

Severe Cases Requiring Hospitalization

Admit patients with systemic symptoms suggesting sepsis risk, such as high fever, rigors, and severe malaise. 2

Intravenous Antibiotic Options:

• Vancomycin 1 g IV every 12 hours – parenteral drug of choice for MRSA or severe infection. 1
• Cefazolin 2 g IV loading dose, then 1 g IV every 8 hours – for penicillin-allergic patients not at high risk for anaphylaxis. 1
• Linezolid 600 mg IV twice daily or daptomycin 4 mg/kg IV once daily – alternative agents for severe cases. 1

Critical Reassessment Points

If symptoms worsen or do not improve within 48-72 hours of starting antibiotics, reevaluation is necessary to rule out an abscess. 1 Obtain:

• Ultrasound imaging – to identify abscess formation, particularly in immunocompromised patients or those with recurrent symptoms. 3
• Milk cultures – to guide antibiotic therapy if not already obtained. 3

Breast Abscess Management

Approximately 10% of mastitis cases progress to breast abscess, which requires drainage. 4, 5 Treatment includes:

• Surgical drainage or needle aspiration – standard treatment once abscess forms. 5, 6
• Breastfeeding can continue on the affected side as long as the infant's mouth does not contact purulent drainage from the breast. 4, 5

Red Flags Requiring Urgent Evaluation

Symptoms persisting beyond 1 week of appropriate antibiotics may indicate inflammatory breast cancer, particularly in non-lactating women, and warrant urgent evaluation. 2 Consider:

• Urgent ultrasound and possible biopsy within 48 hours for erythema occupying at least one-third of breast surface or peau d'orange appearance. 2

Common Pitfalls to Avoid

• Do NOT advise expressing and discarding breast milk – this is illogical given that women after cesarean section are encouraged to breastfeed immediately despite similar drug exposure, and interrupting breastfeeding risks breast engorgement, blocked ducts, and worsening mastitis. 4, 2
• Do NOT recommend excessive pumping, heat application, or aggressive breast massage – these worsen mastitis by overstimulating milk production and causing tissue trauma. 3
• Do NOT discourage breastfeeding during antibiotic treatment – continued breastfeeding helps resolve the mastitis and does not pose risk to the infant. 4, 1