Cephalexin Dosing for Minor Skin Infections
For minor skin infections in adults, the recommended dose of cephalexin is 500 mg orally four times daily for 7-10 days. 1, 2
Adult Dosing
- Standard adult dosage: 500 mg orally four times daily (qid) 2, 1
- Alternative regimen: 250 mg orally four times daily for very mild infections 2
- Duration of therapy: 7-10 days, depending on clinical response 1, 3
- For uncomplicated skin infections, the FDA-approved dosage range is 1-4 g daily in divided doses 3
Pediatric Dosing
- For children: 25-50 mg/kg/day divided into 4 doses 3, 2, 1
- For more severe infections, dosage may be doubled 3
- Duration of therapy: 7-10 days, depending on clinical response 1
Clinical Considerations
- Cephalexin is effective against common skin pathogens including methicillin-susceptible Staphylococcus aureus (MSSA) and Streptococcus species 2
- Cephalexin is ineffective against methicillin-resistant Staphylococcus aureus (MRSA) 2
- Clinical response should be evident within 48-72 hours of initiating therapy 1
- If no improvement is seen within 72 hours, consider alternative diagnoses or resistant organisms 1
- Complete the full course of antibiotics even if symptoms improve before completion 1
Special Populations
- For patients with penicillin allergy (except those with immediate hypersensitivity reactions), cephalexin is a suitable alternative 2
- For suspected MRSA infections, consider alternative agents such as trimethoprim-sulfamethoxazole, clindamycin, or linezolid 2
Efficacy
- Clinical studies have shown comparable efficacy between cephalexin and newer antibiotics for uncomplicated skin infections 4, 5
- In a study comparing cephalexin with cefdinir, both antibiotics showed similar clinical cure rates of approximately 88-89% 6
- In pediatric patients, cephalexin has demonstrated clinical cure rates of 93.8% for skin infections 7
Common Pitfalls and Caveats
- Cephalexin is ineffective against MRSA; if MRSA is suspected, alternative antibiotics should be considered 2
- Gastrointestinal side effects (particularly diarrhea) are the most common adverse reactions 4, 6
- For patients with severe infections or those caused by less susceptible organisms, larger doses may be needed 3
- If daily doses greater than 4 g are required, parenteral cephalosporins should be considered 3