What is the recommended treatment for a boil?

Treatment of Boils

The recommended primary treatment for boils (furuncles) is incision and drainage, with antibiotics generally unnecessary unless there are signs of systemic infection or specific risk factors. 1

Understanding Boils

Boils (furuncles) are infections of the hair follicle, usually caused by Staphylococcus aureus, where suppuration extends through the dermis into the subcutaneous tissue, forming a small abscess. They appear as inflammatory nodules with overlying pustules through which hair emerges. When several adjacent follicles become infected, they can form a carbuncle, which is a coalescent inflammatory mass with pus draining from multiple follicular orifices 1.

Treatment Algorithm

Step 1: Assess the Boil

• Small furuncles: Apply moist heat to promote spontaneous drainage 1
• Large furuncles and all carbuncles: Require incision and drainage 1

Step 2: Incision and Drainage Procedure

1. Provide appropriate anesthesia
2. Make an adequate incision
3. Thoroughly evacuate the pus
4. Probe the cavity to break up loculations 1
5. Cover the surgical site with a dry dressing (packing is generally not necessary and may cause more pain) 1

Step 3: Determine Need for Antibiotics

Systemic antibiotics are generally not required unless the following are present:

• Fever or other evidence of systemic infection 1
• Systemic inflammatory response syndrome (SIRS) such as:
  • Temperature >38°C or <36°C
  • Tachypnea >24 breaths per minute
  • Tachycardia >90 beats per minute
  • White blood cell count >12,000 or <400 cells/µL 1
• Markedly impaired host defenses 1
• Extensive surrounding cellulitis 1
• Multiple lesions 1

Step 4: Cultures

• Gram stain and culture of pus from boils are recommended, but treatment without these studies is reasonable in typical cases 1

Special Considerations

For Recurrent Boils

1. Search for local causes (e.g., pilonidal cyst, hidradenitis suppurativa, foreign material) 1
2. Drain and culture early in the course of infection 1
3. Consider a 5-10 day course of antibiotics active against the isolated pathogen 1
4. Consider a 5-day decolonization regimen:
   • Intranasal mupirocin twice daily
   • Daily chlorhexidine washes
   • Daily decontamination of personal items (towels, sheets, clothes) 1

Risk Factors for Recurrence

Several factors increase the risk of recurrent boils 2:

• Obesity (RR 1.3)
• Diabetes (RR 1.3)
• Smoking (RR 1.3)
• Age <30 years (RR 1.2)
• Prior antibiotic use (RR 1.4)

Important Caveats

1. Do not attempt needle aspiration - This has been shown to be successful in only 25% of cases overall and <10% with MRSA infections 1

2. Avoid home lancing - Self-lancing of boils can lead to severe invasive infections, as documented in case reports 3

3. Watch for complications - Inadequate drainage can lead to spread of infection, and misdiagnosis of entities such as mycotic aneurysms can occur 4

4. Consider MRSA coverage - If antibiotics are needed, consider MRSA coverage in patients with risk factors or who don't respond to first-line therapy 1

5. Monitor for recurrence - Approximately 10% of patients with a boil develop a repeat boil within 12 months 2

The evidence suggests that proper incision and drainage is the cornerstone of treatment for boils, with antibiotics reserved for specific situations. Following this approach can effectively manage boils while minimizing unnecessary antibiotic use.