Best Medicine and Management for Boils (Furuncles) in Adults
Incision and drainage is the primary treatment for large furuncles and all carbuncles, and antibiotics are usually unnecessary unless the patient has fever or signs of systemic infection (SIRS criteria). 1
Cause
Furuncles are infections of the hair follicle caused by Staphylococcus aureus, where suppuration extends through the dermis into subcutaneous tissue forming a small abscess 1. They differ from superficial folliculitis where pus remains limited to the epidermis. When infection involves several adjacent follicles, it forms a carbuncle—a larger, deeper coalescent inflammatory mass with pus draining from multiple follicular openings 1.
Primary Management Algorithm
Step 1: Assess Severity and Need for Drainage
- Small furuncles: Often rupture and drain spontaneously or with moist heat application 1
- Large furuncles and all carbuncles: Require incision and drainage 1
- After drainage: Simply cover with dry sterile gauze—packing causes more pain without improving healing 1
Step 2: Determine if Antibiotics Are Needed
Antibiotics are NOT routinely needed after incision and drainage unless specific criteria are met 1:
Give antibiotics ONLY if patient has SIRS criteria:
- Temperature >38°C or <36°C
- Tachypnea >24 breaths/minute
- Tachycardia >90 beats/minute
- White blood cell count >12,000 or <4,000 cells/µL
OR if patient has:
- Markedly impaired host defenses (immunocompromised)
- Diabetes (carbuncles commonly occur on back of neck in diabetics) 1
Step 3: Antibiotic Selection When Indicated
When antibiotics are needed, choose based on MRSA risk:
For MRSA coverage (required if SIRS present or immunocompromised) 1:
- Doxycycline
- Clindamycin
- Trimethoprim-sulfamethoxazole (SMX-TMP)
For methicillin-susceptible S. aureus (most furuncles/carbuncles):
- Oral penicillinase-resistant penicillin
- First-generation cephalosporins (e.g., cephalexin, cefadroxil)
The evidence comparing different oral antibiotics shows no clinically important differences in cure rates. For example, cefdinir versus cefalexin showed similar clinical cure rates (RR 1.00,95% CI 0.73-1.38) 2, and cefditoren pivoxil versus cefaclor also showed no difference (RR 1.17,95% CI 0.77-1.78) 2.
Step 4: Culture Considerations
- Gram stain and culture of pus from carbuncles and abscesses are recommended but treatment without these studies is reasonable in typical cases 1
- Culture is particularly important for recurrent infections 1
Management of Recurrent Furuncles
If furuncles recur, implement decolonization strategy 1:
Culture the abscess early and treat with 5-10 day course of antibiotic active against isolated pathogen 1
5-day decolonization regimen for recurrent S. aureus 1:
- Intranasal mupirocin twice daily
- Daily chlorhexidine washes
- Daily decontamination of personal items (towels, sheets, clothes)
Search for underlying causes 1:
- Pilonidal cyst
- Hidradenitis suppurativa
- Foreign material
Long-term suppressive azithromycin (500 mg weekly for 12 weeks) showed 79% effectiveness in preventing recurrent furunculosis caused by methicillin-sensitive S. aureus 3. Fusidic acid ointment applied to nares twice daily every 4th week for 4-15 months had permanent effect in 80% of patients 4.
Common Pitfalls to Avoid
- Don't use needle aspiration: Only 25% successful overall and <10% with MRSA—incision and drainage is superior 1
- Don't prescribe antibiotics reflexively: Most furuncles after drainage don't need antibiotics 1
- Don't ignore recurrence patterns: 10% of patients develop repeat boils within 12 months 5. Risk factors include obesity, diabetes, age <30 years, smoking, and recent antibiotic use 5
- Don't pack wounds routinely: Packing causes more pain without improving healing compared to simple gauze coverage 1
Key Risk Factors for Recurrence
Patients with these factors have higher recurrence risk and may benefit from more aggressive decolonization 5:
- Obesity (RR 1.3)
- Diabetes (RR 1.3)
- Smoking (RR 1.3)
- Age <30 years (RR 1.2)
- Prior antibiotic use (RR 1.4)