What is the standard dosing of Keflex (cephalexin) for soft tissue infections?

Standard Keflex (Cephalexin) Dosing for Soft Tissue Infections

For soft tissue infections in adults, the standard dosing of Keflex (cephalexin) is 500 mg orally every 6 hours for 5-7 days. 1, 2

Adult Dosing Options

• Standard dose: 500 mg orally every 6 hours (2 g daily) 1
• Alternative regimen: 500 mg orally every 12 hours for less severe infections 1
• Higher dose for severe infections: Up to 4 g daily in divided doses may be used 1

Pediatric Dosing

• Standard dose: 25-50 mg/kg/day in 4 divided doses 1
• Alternative regimen: Total daily dose may be divided and administered every 12 hours 1
• For severe infections: Dosage may be doubled 1

Duration of Therapy

• The recommended duration for most soft tissue infections is 5 days 2
• Treatment should be extended if the infection has not improved within this time period 2
• For more severe or complicated infections, 7-14 days may be necessary 3

Clinical Considerations

Factors Affecting Dosing

• Renal impairment: Dose adjustment required for patients with creatinine clearance <30 mL/min 4
• Severity of infection: More severe infections may require higher doses or longer duration
• Patient age and weight: Pediatric dosing is weight-based

Efficacy and Coverage

• Cephalexin is effective against most common soft tissue pathogens including:
  • Streptococci (primary target for cellulitis)
  • Methicillin-susceptible Staphylococcus aureus (MSSA)
  • Does NOT cover MRSA, which requires alternative antibiotics 2

Administration Tips

• Can be taken with or without food
• If GI upset occurs, taking with food may help reduce symptoms
• Suspension should be refrigerated after reconstitution and can be kept for 14 days 1

Common Pitfalls to Avoid

1. Inadequate duration: Stopping therapy too early can lead to treatment failure
2. Inadequate coverage: Cephalexin does not cover MRSA, so consider risk factors for MRSA when selecting therapy
3. Missing adjunctive measures: Elevation of affected limb is recommended to reduce edema 3
4. Overlooking underlying conditions: Conditions like tinea pedis or venous eczema should be treated to prevent recurrence 3
5. Expecting immediate improvement: Some patients may experience worsening inflammation initially after starting antibiotics 3

Special Situations

• For patients with recurrent abscesses, consider a 5-day decolonization regimen with intranasal mupirocin, daily chlorhexidine washes, and daily decontamination of personal items 2
• For severe infections with systemic signs, hospitalization and IV antibiotics may be necessary 2

Cephalexin remains a first-line option for most uncomplicated soft tissue infections, with clinical studies showing high cure rates (>90%) when used at appropriate doses 5, 6.