What are the recommended dosages of clindamycin (Clindamycin) and Keflex (Cephalexin) for skin infections?

Recommended Oral Dosages for Clindamycin and Cephalexin in Skin Infections

For skin and soft tissue infections, clindamycin should be dosed at 300-450 mg orally three times daily for adults and 10-20 mg/kg/day divided into 3 doses for children, while cephalexin (Keflex) should be dosed at 500 mg four times daily for adults, though evidence suggests both agents may be unnecessary after adequate drainage of simple abscesses. 1, 2

Clindamycin Dosing

Adult Dosing

• Standard oral dose: 300-450 mg three times daily (every 8 hours) for uncomplicated skin and soft tissue infections 1, 2
• For severe or complicated infections requiring IV therapy: 600-900 mg IV every 8 hours, then transition to oral therapy after clinical improvement 1, 2
• Duration: 7-10 days depending on clinical response 2

Pediatric Dosing

• Oral: 10-20 mg/kg/day divided into 3 doses (or 25-40 mg/kg/day for more severe infections) 1, 2
• IV dosing for severe infections: 10-13 mg/kg/dose every 6-8 hours, not exceeding 40 mg/kg/day total 1

When to Choose Clindamycin

• Purulent infections (abscesses, furuncles) after incision and drainage 2
• When MRSA coverage is needed - clindamycin provides excellent coverage against both MRSA and beta-hemolytic streptococci 1, 2
• Penicillin-allergic patients 2
• Only use when local MRSA clindamycin resistance rates are <10% due to risk of inducible resistance in erythromycin-resistant strains 1, 2

Cephalexin (Keflex) Dosing

Adult Dosing

• Standard dose: 500 mg orally four times daily for skin and soft tissue infections 3
• Alternative dosing: 500 mg twice daily has shown equal efficacy to four times daily dosing in clinical trials 3

Pediatric Dosing

• Dosing based on weight and severity, typically following standard cephalosporin dosing guidelines for skin infections

Critical Clinical Decision Algorithm

For Simple Abscesses (After Adequate Drainage)

1. If adequately drained with minimal surrounding cellulitis (<5 cm erythema): Consider observation without antibiotics - cure rates of 90.5% with drainage alone have been demonstrated even in MRSA-predominant populations 4
2. If surrounding cellulitis present or high-risk features: Add antibiotics

Antibiotic Selection Strategy

1. If MRSA suspected or confirmed AND local clindamycin resistance <10%: Use clindamycin 300-450 mg PO TID 1, 2
2. If methicillin-susceptible organisms suspected: Either cephalexin 500 mg QID or clindamycin can be used - a randomized trial showed no significant difference (94% vs 97% improvement at 48-72 hours) 5
3. If penicillin allergy: Clindamycin is the preferred single agent 2

Important Evidence-Based Considerations

The Role of Drainage vs. Antibiotics

• Incision and drainage is the cornerstone of abscess treatment and may be sufficient alone for simple abscesses 1
• A landmark randomized trial demonstrated that in appropriately drained uncomplicated abscesses, there was no significant difference between cephalexin and clindamycin (97% vs 94% complete resolution at 7 days, P=0.33), despite 69% MRSA prevalence 5
• Another placebo-controlled trial showed 90.5% cure with drainage alone vs 84.1% with cephalexin in MRSA-predominant infections (87.8% MRSA), suggesting antibiotics may be unnecessary after adequate drainage 4

Necrotizing Infections (Severe Cases)

For necrotizing fasciitis or severe infections requiring IV therapy:

• Clindamycin 600-900 mg IV every 8 hours combined with other agents as needed 6, 1
• Clindamycin provides superior toxin suppression in streptococcal infections 1

Common Pitfalls to Avoid

1. Underdosing clindamycin: The IDSA guidelines recommend higher doses (300-450 mg TID, not lower doses) for serious infections based on better outcomes 1
2. Using clindamycin in high-resistance areas: Only use when local MRSA clindamycin resistance is <10% 1, 2
3. Prescribing antibiotics without adequate drainage: Antibiotics provide limited benefit without source control 1
4. Inadequate follow-up: Clinical improvement should be evident within 48-72 hours; if not, consider inadequate drainage or deeper infection 1

Monitoring and Duration

• Assess clinical response at 48-72 hours - expect improvement in erythema, pain, and swelling 1, 5
• Complete the full 7-10 day course even if symptoms improve earlier 2
• Fevers and age <1 year are associated with early treatment failures regardless of antibiotic choice 5