At What Size Should a Furuncle Be Lanced?
Size is not the determining factor for lancing a furuncle—instead, lance all furuncles that are fluctuant (indicating pus collection), regardless of size. 1, 2
Primary Treatment Approach
Incision and drainage is the cornerstone of treatment for all large furuncles and carbuncles, as recommended by the Infectious Diseases Society of America. 1, 2
Small furuncles may be treated with moist heat application alone to promote spontaneous drainage without surgical intervention. 1, 2 This conservative approach is appropriate when the lesion is small and not yet fluctuant.
The decision to lance depends on fluctuance (presence of fluid/pus) rather than a specific size cutoff—if you can palpate fluid collection, proceed with incision and drainage. 2, 3
Post-Drainage Management
After drainage, simply cover the wound with a dry dressing—packing with gauze is unnecessary and adds pain without improving outcomes. 2, 4
Systemic antibiotics are NOT routinely needed for simple furuncles after adequate drainage. 1, 2
When to Add Antibiotics
Prescribe antibiotics active against S. aureus ONLY if any of these conditions exist: 1, 2
- Fever or systemic inflammatory response syndrome (SIRS)
- Extensive surrounding cellulitis
- Multiple lesions present
- Markedly impaired host defenses (immunocompromised patients, diabetes)
Use MRSA-active antibiotics (trimethoprim-sulfamethoxazole, doxycycline, or clindamycin) when antibiotics are indicated, given high MRSA prevalence in community-acquired skin infections. 1, 2
Common Pitfalls to Avoid
Do not rely on antibiotics alone without drainage for fluctuant furuncles—this approach will fail because the pus collection must be evacuated. 2, 3
Do not wait for a specific size threshold before draining—fluctuance is the key clinical finding that indicates readiness for incision and drainage. 2
Obtain culture of pus to guide antibiotic therapy if systemic treatment is needed, especially with multiple lesions or recurrent infections. 2, 3