What is the appropriate treatment for impetigo?

Treatment of Impetigo

For limited impetigo, topical mupirocin 2% ointment applied three times daily for 5-7 days is the first-line treatment; for extensive disease, oral antibiotics such as cephalexin or dicloxacillin for 7 days are recommended. 1

First-Line Treatment: Topical Antibiotics for Limited Disease

• Topical mupirocin 2% ointment applied three times daily for 5-7 days is the preferred initial treatment for localized impetigo (up to 100 cm² total area). 1, 2
• Retapamulin 1% ointment applied twice daily for 5 days is an effective alternative for patients aged 9 months or older. 1, 3
• Topical antibiotics achieve cure rates 6-fold higher than placebo and are superior to oral antibiotics for limited disease, with clinical efficacy rates of 71% versus 35% for placebo. 2, 3
• Before applying topical therapy, gently wash the affected area with soap and water to enhance antibiotic penetration. 1

Common pitfall: Topical therapy requires only 5-7 days of treatment, whereas oral antibiotics require a full 7-day course—do not confuse these durations. 3

Second-Line Treatment: Oral Antibiotics for Extensive Disease

Oral antibiotics are indicated when impetigo is extensive, involves multiple sites, topical therapy is impractical, topical treatment has failed, or systemic symptoms are present. 1, 4

For Methicillin-Susceptible S. aureus (MSSA):

• Cephalexin 250-500 mg four times daily for adults (25-50 mg/kg/day in 4 divided doses for children) for 7 days. 3
• Dicloxacillin 250 mg four times daily for adults (25-50 mg/kg/day in 4 divided doses for children) for 7 days. 3
• Amoxicillin-clavulanate is an acceptable alternative for MSSA. 1, 3

For Suspected or Confirmed MRSA:

• Clindamycin 300-450 mg three to four times daily for adults (20-30 mg/kg/day in 3 divided doses for children) for 7 days. 1, 3
• Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily for adults (8-12 mg/kg/day trimethoprim component in 2 divided doses for children) for 7 days. 1, 3
• Doxycycline for patients over 8 years old (2-4 mg/kg/day in 2 divided doses) for 7 days. 1, 3

Critical caveat: Tetracyclines (doxycycline) must be avoided in children under 8 years due to permanent dental staining risk. 3

Antibiotics to Avoid

• Penicillin alone is seldom effective for impetigo and should only be used when cultures confirm streptococci alone, as it lacks adequate coverage against S. aureus. 3
• Amoxicillin alone should not be used because it lacks adequate coverage against S. aureus, which is now the predominant causative organism. 3
• Cefdinir should not be used when MRSA is suspected, documented, or confirmed. 3

Special Considerations for MRSA

• Consider empiric therapy for community-acquired MRSA in patients at risk, those who fail first-line therapy, or in areas with high local MRSA prevalence. 1
• If impetigo is not responding to appropriate therapy after 48-72 hours, obtain cultures of vesicle fluid, pus, or erosions and adjust therapy based on susceptibility results. 4

Infection Control and Adjunctive Measures

• Keep lesions covered with clean, dry bandages to prevent spread. 4, 3
• Encourage frequent handwashing with soap and water, especially after touching lesions. 1
• Do not share towels, washcloths, clothing, or bedding with other household members until treatment is complete. 1
• Wash all clothing, towels, and bedding in hot water daily during the first few days of therapy. 1
• Keep children home from school, daycare, and organized sports until at least 24 hours after initiating antibiotic treatment. 1
• Trim fingernails short to reduce scratching and transmission. 1

When to Seek Prompt Re-evaluation

• Development or worsening of fever during treatment may indicate complications. 1
• Expansion of redness beyond the original lesions or increasing pain suggests disease progression. 1
• No improvement after 48-72 hours of appropriate therapy warrants culture and possible treatment adjustment. 4

Treatment Algorithm Summary

1. For limited impetigo (≤100 cm²): Start with topical mupirocin 2% three times daily for 5-7 days. 1, 2
2. For extensive disease or when topical therapy is impractical: Use oral cephalexin or dicloxacillin for 7 days. 1, 3
3. If MRSA is suspected: Switch to clindamycin, trimethoprim-sulfamethoxazole, or doxycycline (age-appropriate). 1, 3
4. If treatment fails: Obtain cultures and adjust therapy based on susceptibility results. 4

Important note: Topical disinfectants have little evidence supporting their use and should not be used as primary therapy. 3, 5