What is the appropriate management of a boil (furunculosis) in an otherwise healthy adult?

Management of Boils (Furunculosis) in Healthy Adults

For small boils, apply moist heat several times daily to promote spontaneous drainage; for large boils, perform incision and drainage without routine antibiotics unless fever, extensive cellulitis, or systemic signs are present. 1

Initial Treatment Based on Size

Small Furuncles

• Apply moist heat multiple times daily to promote spontaneous drainage 1, 2
• No incision and drainage required for small lesions 1
• Systemic antibiotics are unnecessary for uncomplicated small furuncles 1, 2

Large Furuncles and All Carbuncles

• Incision and drainage is the cornerstone of treatment (strong, high-quality evidence) 1, 2, 3
• After drainage, cover the surgical site with a dry dressing rather than packing with gauze 1
• Culture the pus to identify whether MRSA is present, as this guides prevention strategies 3

When to Add Systemic Antibiotics

Antibiotics are indicated only when specific conditions are present 1, 2:

• Fever or other evidence of systemic infection 1, 2
• Extensive surrounding cellulitis 1, 2, 3
• Systemic inflammatory response syndrome (SIRS) 1, 3
• Markedly impaired host defenses or immunocompromised status 1, 2
• Multiple lesions 1, 2

Antibiotic Selection

• Choose an agent active against S. aureus, the most common causative agent 4, 1
• Consider MRSA coverage in high-prevalence areas or if risk factors are present 1

Management of Recurrent Furunculosis

Primary Prevention Strategy: Decolonization

• Intranasal mupirocin 2% ointment applied twice daily for the first 5 days of each month reduces recurrences by approximately 50% 1, 2, 3
• For more aggressive prevention, oral clindamycin 150 mg once daily for 3 months decreases subsequent infections by approximately 80% 2, 3
• Daily chlorhexidine antibacterial soap washes are effective in reducing recurrences 1, 2, 3

Hygiene and Environmental Measures

• Thoroughly launder all clothing, towels, bed linens, and athletic gear in hot water 1, 2, 3
• Enforce strict use of separate towels and washcloths—do not share with others 1, 2, 3
• Decontamination of personal items helps reduce recurrences 1
• Treat household contacts and close contacts who are colonized, as this significantly reduces recurrences 2

Evaluation for Predisposing Factors

• The most important predisposing factor is S. aureus colonization in the anterior nares or perineum 2
• Inadequate personal hygiene and exposure to others with active furuncles are major risk factors 2
• Evaluate for underlying neutrophil dysfunction if recurrences begin in early childhood, though this is rare in adults 2, 3

Common Pitfalls to Avoid

• Do not rely on antibiotics alone without addressing nasal carriage—this will not prevent recurrences 3
• Do not apply moist heat to large furuncles or carbuncles—these require incision and drainage, not conservative management 3
• Do not rely solely on topical decolonization; intranasal mupirocin alone did not reduce MRSA skin infections in one randomized trial 2
• Do not prescribe tetracyclines, including doxycycline, in children under 8 years of age 2

Occupation-Specific Considerations

For patients with prolonged sitting (e.g., drivers) 3:

• Take frequent breaks from sitting every 1-2 hours to reduce friction and maceration 3
• Maintain dry skin in the gluteal area, as moisture and friction create an environment conducive to bacterial colonization 3

When to Seek Further Evaluation

• Development of fever, extensive cellulitis, or signs of systemic infection 3
• Failure of lesions to improve with conservative measures and hygiene protocols 3
• Recurrence despite appropriate decolonization efforts, which may warrant investigation for underlying immunodeficiency 3