What antibiotic regimen is appropriate for uncomplicated nasal cellulitis in an otherwise healthy adult?

Antibiotic Treatment for Nasal Cellulitis

For uncomplicated nasal cellulitis in an otherwise healthy adult, use cephalexin 500 mg orally every 6 hours for 5 days, or dicloxacillin 250–500 mg orally every 6 hours for 5 days. 1, 2

First-Line Treatment Regimen

Beta-lactam monotherapy is the standard of care for typical nonpurulent cellulitis, achieving a 96% clinical success rate because the primary pathogens are beta-hemolytic streptococci (especially Streptococcus pyogenes) and methicillin-sensitive Staphylococcus aureus. 1, 2 MRSA is an uncommon cause of typical cellulitis even in high-prevalence settings, making routine MRSA coverage unnecessary. 1, 2

Recommended oral beta-lactam options:

• Cephalexin 500 mg orally every 6 hours 1, 2
• Dicloxacillin 250–500 mg orally every 6 hours 1, 2, 3
• Amoxicillin-clavulanate 875/125 mg orally twice daily 2, 3

Treatment Duration

Treat for exactly 5 days if clinical improvement occurs (resolution of warmth and tenderness, improving erythema, no fever); extend only if symptoms have not improved within this timeframe. 1, 2 High-quality randomized controlled trial evidence demonstrates that 5-day courses are as effective as 10-day courses for uncomplicated cellulitis. 2 Traditional 7–14 day regimens are no longer necessary. 2

When to Add MRSA Coverage

Add MRSA-active antibiotics only when specific risk factors are present: 1, 2

• Penetrating trauma (e.g., nasal piercing, recent nasal surgery) 1, 2
• Purulent drainage or exudate visible at the infection site 1, 2
• Known MRSA colonization or prior MRSA infection 2
• Systemic inflammatory response syndrome (fever >38°C, heart rate >90 bpm, respiratory rate >24 breaths/min) 1, 2
• Failure to respond to beta-lactam therapy after 48–72 hours 2

If MRSA coverage is needed, use:

• Clindamycin 300–450 mg orally every 6 hours (provides single-agent coverage for both streptococci and MRSA, but use only if local MRSA clindamycin resistance is <10%) 1, 2, 4
• Trimethoprim-sulfamethoxazole 1–2 double-strength tablets twice daily PLUS a beta-lactam (cephalexin or amoxicillin) 1, 2
• Doxycycline 100 mg orally twice daily PLUS a beta-lactam 2

Penicillin Allergy Considerations

For patients with penicillin allergy (except immediate hypersensitivity reactions like anaphylaxis, angioedema, or urticaria), cephalexin remains an option because cross-reactivity between penicillins and cephalosporins is only 2–4%. 2 However, avoid cephalexin in patients with confirmed immediate-type amoxicillin allergy because they share identical R1 side chains. 2

For true penicillin-allergic patients:

• Clindamycin 300–450 mg orally every 6 hours (if local MRSA clindamycin resistance is <10%) 1, 2, 4

Critical Pitfalls to Avoid

• Do not routinely add MRSA coverage for typical nonpurulent nasal cellulitis without specific risk factors; this represents overtreatment and promotes antibiotic resistance. 1, 2
• Do not use doxycycline or trimethoprim-sulfamethoxazole as monotherapy for typical cellulitis because they lack reliable activity against beta-hemolytic streptococci. 1, 2
• Do not extend treatment to 7–10 days automatically; extend only if warmth, tenderness, or erythema have not improved after 5 days. 1, 2
• Do not delay reassessment; evaluate the patient within 24–48 hours to verify clinical response, as treatment failure rates of 21% have been reported with some oral regimens. 2

Hospitalization Criteria

Hospitalize if any of the following are present: 1, 2

• Systemic inflammatory response syndrome (fever, tachycardia, hypotension, altered mental status)
• Concern for deeper or necrotizing infection (severe pain out of proportion to examination, skin anesthesia, rapid progression, "wooden-hard" subcutaneous tissue)
• Severe immunocompromise or neutropenia
• Failure of outpatient treatment after 24–48 hours

For hospitalized patients requiring IV therapy, use cefazolin 1–2 g IV every 8 hours or nafcillin 2 g IV every 6 hours. 2 For severe cellulitis with systemic toxicity, use vancomycin 15–20 mg/kg IV every 8–12 hours PLUS piperacillin-tazobactam 3.375–4.5 g IV every 6 hours. 1, 2

Adjunctive Measures

• Elevate the head to promote gravity drainage of edema and inflammatory substances. 1, 2
• Treat predisposing conditions such as nasal trauma, chronic rhinitis, or nasal vestibulitis. 1, 2
• Reassess within 24–48 hours to ensure clinical improvement. 2