What is the best antibiotic for facial cellulitis?

Best Antibiotic for Facial Cellulitis

For typical nonpurulent facial cellulitis, use a beta-lactam antibiotic such as cephalexin 500 mg orally every 6 hours or dicloxacillin 250-500 mg orally every 6 hours for 5 days, as beta-lactam monotherapy is successful in 96% of cases and MRSA coverage is unnecessary unless specific risk factors are present. 1

First-Line Treatment Selection

• Cephalexin 500 mg orally every 6 hours is the preferred first-line agent for typical facial cellulitis, providing effective coverage against streptococci (the primary pathogen) and methicillin-sensitive S. aureus 2

• Dicloxacillin 250-500 mg orally every 6 hours is equally effective as first-line therapy for uncomplicated facial cellulitis 2

• Amoxicillin or penicillin V 250-500 mg orally four times daily are also appropriate beta-lactam options 1

• The Infectious Diseases Society of America establishes that beta-lactam monotherapy is the standard of care, with MRSA being an uncommon cause of typical cellulitis even in high-prevalence settings 1

Treatment Duration

• Treat for exactly 5 days if clinical improvement occurs—extending treatment only if symptoms have not improved within this timeframe 1, 3

• Five-day courses are as effective as 10-day courses for uncomplicated cellulitis, based on high-quality randomized controlled trial evidence showing 98% success rates with both durations 3

• Traditional 7-14 day courses are no longer necessary for uncomplicated cases 1

When to Add MRSA Coverage

Do NOT routinely add MRSA coverage for typical facial cellulitis. Add MRSA-active antibiotics ONLY when these specific risk factors are present: 1, 2

• Penetrating trauma to the face
• Purulent drainage or exudate visible
• Evidence of MRSA infection elsewhere on the body
• Known nasal MRSA colonization
• Systemic inflammatory response syndrome (fever >38°C, tachycardia >90 bpm, hypotension)
• Failure to respond to beta-lactam therapy after 48-72 hours

MRSA Coverage Options (When Indicated)

If specific risk factors mandate MRSA coverage: 1, 2

• Clindamycin 300-450 mg orally every 6 hours alone (covers both streptococci and MRSA in a single agent) 1
• Trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 DS tablets twice daily PLUS a beta-lactam (cephalexin or amoxicillin) 1
• Doxycycline 100 mg orally twice daily PLUS a beta-lactam 1

Critical caveat: Never use TMP-SMX or doxycycline as monotherapy for facial cellulitis, as their activity against beta-hemolytic streptococci is unreliable 1

Penicillin Allergy Considerations

• For patients with penicillin allergy, use clindamycin 300-450 mg orally every 6 hours, as 99.5% of S. pyogenes strains remain susceptible 2

• For cephalosporin-allergic patients, penicillin V or clindamycin are appropriate alternatives, as cross-reactivity among beta-lactams with dissimilar side chains is less common than historically believed 1

Hospitalization Criteria

Admit patients with facial cellulitis who have: 1, 2

• Systemic inflammatory response syndrome (fever, altered mental status, hemodynamic instability)
• Hypotension or hemodynamic instability
• Altered mental status or confusion
• Severe immunocompromise or neutropenia
• Concern for deeper or necrotizing infection (severe pain out of proportion to exam, skin anesthesia, rapid progression, bullous changes)
• Failure of outpatient treatment after 24-48 hours

Intravenous Options for Severe Cases

For hospitalized patients requiring parenteral therapy: 1

• Cefazolin 1-2 g IV every 8 hours is the preferred IV beta-lactam for uncomplicated cases requiring hospitalization 1
• Vancomycin 15-20 mg/kg IV every 8-12 hours for MRSA coverage when risk factors present 1
• Vancomycin PLUS piperacillin-tazobactam 3.375-4.5 g IV every 6 hours for severe cellulitis with systemic toxicity or suspected necrotizing fasciitis 1

Essential Adjunctive Measures

• Elevate the affected area (head of bed elevated) to promote gravity drainage of edema and inflammatory substances 2
• Examine for and treat predisposing conditions such as trauma, venous eczema, or underlying skin conditions 2
• Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in nondiabetic adults to potentially hasten resolution, though evidence is limited 2

Common Pitfalls to Avoid

• Do not reflexively add MRSA coverage for typical facial cellulitis without specific risk factors—this represents overtreatment and increases antibiotic resistance 1, 2

• Do not extend treatment beyond 5 days automatically—only extend if clinical improvement has not occurred 1

• Do not use TMP-SMX or doxycycline alone for facial cellulitis, as streptococcal coverage will be inadequate 1

• Do not delay surgical consultation if any signs of necrotizing infection are present (severe pain out of proportion, rapid progression, skin anesthesia, gas in tissue) 1

Monitoring Response

• Reassess within 24-48 hours to verify clinical response 1

• If no improvement with appropriate first-line antibiotics, consider resistant organisms (add MRSA coverage), cellulitis mimickers (deep vein thrombosis, contact dermatitis), or underlying complications (abscess requiring drainage) 1

• Blood cultures are positive in only 5% of cases and are unnecessary for typical facial cellulitis, but obtain them in patients with severe systemic features, malignancy, or neutropenia 1