Cephalexin Dosing and Spectrum for MSSA‑Related Infections

Guideline‑Based Dosing for MSSA

Pediatric pneumonia guidelines recommend a total daily dose of 75–100 mg/kg of cephalexin, divided into 3–4 doses, to treat MSSA infections in children. This translates to higher per‑dose amounts than standard low‑dose regimens. Strength of evidence: guideline recommendation. 1
Higher oral cephalexin doses (e.g., 1000 mg every 8 hours, totaling 3 g/day) are advised for moderate‑to‑severe MSSA infections in adults, reflecting the need for increased drug exposure. Strength of evidence: clinical guideline/expert consensus. 2

For skin and soft‑tissue infections caused by MSSA, cephalexin is identified as a preferred oral antimicrobial due to its efficacy and safety profile. Strength of evidence: infectious‑disease guideline recommendation. 3

Cephalexin does not cover the following organisms:
Strength of evidence: microbiologic susceptibility data. 3

First‑generation cephalosporins, including cephalexin, are ineffective for the treatment of Lyme disease. Strength of evidence: clinical study demonstrating lack of efficacy. 5