What medications are used to treat mastitis?

Mastitis Medication

For lactational mastitis in breastfeeding women, first-line antibiotic therapy is dicloxacillin 500 mg orally four times daily or cephalexin 500 mg orally four times daily, targeting Staphylococcus aureus, which causes the majority of infectious mastitis cases. 1

When to Start Antibiotics

• Begin with a 1-2 day trial of conservative measures first (NSAIDs, ice application, direct breastfeeding, minimizing pumping) before initiating antibiotics, as most mastitis cases are inflammatory rather than truly infectious 2
• Start antibiotics if symptoms do not improve within 24-48 hours of conservative management 2
• Initiate antibiotics immediately if the patient appears systemically ill with high fever or signs of sepsis 2

First-Line Antibiotic Options

Preferred Agents

• Dicloxacillin 500 mg orally four times daily is the oral agent of choice for methicillin-susceptible S. aureus 1, 3
• Cephalexin 500 mg orally four times daily is an equally effective alternative, particularly useful for penicillin-allergic patients 1
• Both agents are safe during breastfeeding with minimal transfer to breast milk 1, 4
• Dicloxacillin has a relative infant dose of only 0.03%, well below the 10% threshold of concern 4

Alternative Antibiotics

• Amoxicillin/clavulanic acid is a broad-spectrum option safe during breastfeeding based on limited human data 1
• Clindamycin should be considered for suspected or confirmed MRSA, though use with caution as it may increase gastrointestinal side effects in the infant 1
• Erythromycin or azithromycin are acceptable for penicillin-allergic patients, but carry a very low risk of infantile hypertrophic pyloric stenosis if used during the first 13 days of infant life 1

MRSA Coverage Considerations

• Consider MRSA coverage if local MRSA prevalence is high, patient has previous MRSA infection, or there is no response to first-line therapy 1
• As methicillin-resistant S. aureus becomes more common, antibiotics effective against this organism may become preferred first-line agents 5

Duration and Monitoring

• Reevaluate within 48-72 hours if symptoms worsen or do not improve after starting antibiotics to rule out abscess formation 1
• Obtain milk cultures to guide antibiotic therapy, especially in cases not responding to initial treatment 2
• Consider alternative antibiotics based on culture results 1

Critical Management Principles

• Continue breastfeeding during antibiotic treatment - this does not pose risk to the infant and helps resolve the mastitis 1, 5
• Encourage frequent, complete emptying of the breast through direct breastfeeding rather than pumping 5, 2
• Breast abscess occurs in approximately 10% of mastitis cases and can be prevented by early antibiotic treatment and continued breastfeeding 1, 5

Common Pitfalls to Avoid

• Do not recommend excessive pumping, heat application, or aggressive breast massage - these practices overstimulate milk production and cause tissue trauma, potentially worsening the condition 2
• Do not delay antibiotic therapy beyond 48 hours if conservative measures fail 2
• Do not discontinue breastfeeding from the affected breast during treatment 5, 3
• Probiotics for treatment or prevention are not supported by good evidence 2

Inpatient Management

• Hospital admission with intravenous antibiotics is required if the condition worsens or there is concern for sepsis 2
• Perform ultrasonography to identify abscesses in immunocompromised patients or those with worsening or recurrent symptoms 2