Cephalexin Dosing for Mastitis
For lactating women with mastitis, cephalexin should be dosed at 500 mg orally four times daily (every 6 hours) for 7-10 days, as this provides effective coverage against Staphylococcus aureus, the most common causative pathogen. 1, 2
Recommended Dosing Regimen
- Standard dose: 500 mg orally every 6 hours (four times daily) 3, 1
- Duration: 7-10 days depending on clinical response 1
- Timing: Can be taken with or without food, though absorption occurs in the upper intestine 4
Rationale for This Dosing
The 500 mg four times daily regimen is specifically recommended by the Infectious Diseases Society of America for skin and soft tissue infections caused by methicillin-susceptible Staphylococcus aureus (MSSA), which is the predominant pathogen in mastitis 3, 1. This dosing achieves:
- Adequate tissue concentrations to treat staphylococcal infections 1
- Therapeutic levels in breast milk (0.09-0.59 mcg/mL in healthy milk, 0.57-1.05 mcg/mL in infected milk) 5
- Minimal disruption to breastfeeding, as cephalexin is considered safe for the nursing infant 2
Clinical Considerations for Mastitis
Continue breastfeeding during treatment - this is crucial for both therapeutic success and does not pose risk to the infant 2. Frequent, complete breast emptying reduces the risk of progression to abscess 2.
When to Consider Alternative Antibiotics
- If MRSA is suspected or confirmed: Switch to agents effective against methicillin-resistant S. aureus such as trimethoprim-sulfamethoxazole or clindamycin 3, 2
- If no clinical improvement within 48-72 hours: Consider MRSA coverage or breast abscess formation 2
- Penicillin allergy: Cephalexin can still be used in most cases unless there is a history of severe IgE-mediated reaction 3
Adjunctive Management
- Optimize breastfeeding technique, ideally with lactation consultant assistance 2
- Address predisposing factors such as nipple trauma or poor latch 2
- Monitor for abscess formation (most common complication), which requires drainage 2