Keflex (Cephalexin) Dosage for Skin Infections
For typical skin infections in adults, Keflex (cephalexin) should be administered at 500 mg orally four times daily for 7-10 days. 1, 2
Adult Dosing
- Standard adult dosage for skin infections: 500 mg orally four times daily (qid) 2
- Alternative dosing regimen: 500 mg orally every 12 hours (twice daily) 1
- Duration of therapy: 7-10 days, depending on clinical response 2
- For more severe infections, dosage may be increased up to 4 g daily in divided doses 1
Pediatric Dosing
- Standard pediatric dosage: 25-50 mg/kg/day divided into 4 doses 1, 2
- For children weighing less than 40 kg: 25-50 mg/kg/day in 4 divided doses 2
- For children weighing more than 40 kg: adult dosing can be used 1
- Duration of therapy: 7-10 days, depending on clinical response 2
Clinical Considerations
- Cephalexin is effective against common skin pathogens including methicillin-susceptible Staphylococcus aureus (MSSA) and Streptococcus species 2
- For patients with penicillin allergy (except those with immediate hypersensitivity reactions), cephalexin is a suitable alternative 2
- Cephalexin is ineffective against methicillin-resistant Staphylococcus aureus (MRSA) 2
- For suspected MRSA infections, consider alternative agents such as trimethoprim-sulfamethoxazole, clindamycin, or linezolid 2
Special Populations
- For patients with renal impairment: dosage adjustment may be required 1
- For pregnant patients: Cephalexin is FDA pregnancy category B and generally considered safe 2
Monitoring and Follow-up
- Clinical response should be evident within 48-72 hours of initiating therapy 2
- If no improvement is seen within 72 hours, consider alternative diagnoses or resistant organisms 2
- Complete the full course of antibiotics even if symptoms improve before completion 2
Common Side Effects
- Gastrointestinal symptoms (diarrhea, nausea, vomiting) 3
- Skin reactions (rash, pruritus) 3
- Hypersensitivity reactions (rare but serious) 1
Evidence from Clinical Trials
- Clinical studies have shown cephalexin to be effective in 90-96% of patients with skin and soft tissue infections 4, 3
- Comparative studies have demonstrated similar efficacy between cephalexin and other antibiotics such as azithromycin, ofloxacin, and moxifloxacin for uncomplicated skin infections 4, 5, 6
Cephalexin remains a first-line agent for skin infections caused by susceptible organisms due to its proven efficacy, favorable safety profile, and cost-effectiveness 2.