What is the treatment for a furuncle (boil) on the back?

Treatment of Furuncle on the Back

For a furuncle on the back, apply moist heat several times daily if small to promote spontaneous drainage, but perform incision and drainage if large—systemic antibiotics are unnecessary unless fever, extensive cellulitis, or multiple lesions are present. 1, 2

Initial Treatment Algorithm

Small Furuncles

• Apply warm, moist compresses to the affected area several times daily to bring the infection to a head and facilitate natural drainage 3, 1, 4
• This conservative approach achieves an 85-90% cure rate with drainage alone 4
• No systemic antibiotics are needed for uncomplicated cases 3, 1, 2

Large Furuncles

• Perform incision and drainage—this is the definitive treatment (strong recommendation, high-quality evidence) 3, 1, 2
• After drainage, cover the wound with a dry dressing rather than packing with gauze, as packing adds unnecessary pain without improving outcomes 1, 2

When to Add Systemic Antibiotics

Prescribe antibiotics active against S. aureus ONLY if any of these conditions exist: 3, 1, 2

• Fever or systemic inflammatory response syndrome (SIRS)
• Extensive surrounding cellulitis
• Multiple lesions present
• Markedly impaired host defenses (immunocompromised status, diabetes)

Antibiotic Selection

• Choose MRSA-active agents given high community prevalence: trimethoprim-sulfamethoxazole, doxycycline, or clindamycin 2
• Consider local resistance patterns when selecting clindamycin (use only if local resistance <10%) 4

Management of Recurrent Furunculosis

If furuncles recur despite adequate initial treatment: 1, 2

Decolonization Protocol

• Apply intranasal mupirocin 2% ointment twice daily for 5 days each month—this reduces recurrences by approximately 50% 3, 1, 2
• Perform daily chlorhexidine body washes for 5-14 days 1, 2
• Daily decontamination of personal items including towels, sheets, and clothing 1, 2

Alternative Long-Term Suppression

• For recurrent cases caused by susceptible S. aureus, oral clindamycin 150 mg daily for 3 months decreases subsequent infections by approximately 80% 3
• This represents the most effective program for recurrent disease when decolonization measures fail 3, 5, 6

Household Transmission Control

• Evaluate all household contacts for evidence of S. aureus infection if transmission is suspected 2
• Apply hygiene measures to all household members, not just the affected individual 2
• Use separate towels and washcloths for the affected person 1, 2
• Clean surfaces that contact bare skin daily with commercial cleaners 2

Important Clinical Caveats

Common pitfall: Prescribing antibiotics for simple furuncles after adequate drainage—this is unnecessary and contributes to resistance 3, 1, 2

Key consideration: Nasal colonization with S. aureus is the primary identifiable predisposing factor for recurrent disease, present in 20-40% of the general population 3, 2

When to investigate further: Search for anatomic causes (pilonidal cyst, hidradenitis suppurativa, retained foreign material) if furuncles continue to recur despite decolonization efforts 2

Screening cultures: NOT routinely recommended before decolonization if at least one prior infection was documented as MRSA 2