What antibiotics (abx) are recommended for a boil on the back?

Antibiotic Treatment for Boils on the Back

For a boil on the back, incision and drainage is the primary treatment, with antibiotics only needed if there are signs of systemic illness, extensive disease, or other complicating factors. 1

Primary Treatment Approach

1. Incision and drainage:

   • This is the definitive treatment for boils (furuncles) 1
   • For simple, uncomplicated boils, incision and drainage alone is typically adequate 1

2. When to add antibiotics:

   • Antibiotics are indicated when the boil is associated with:
     • Severe or extensive disease (multiple sites of infection)
     • Rapid progression with associated cellulitis
     • Signs of systemic illness (fever >38°C, tachypnea >24 breaths/min, tachycardia >90 beats/min, WBC >12,000 or <400 cells/μL)
     • Comorbidities or immunosuppression
     • Extremes of age
     • Location difficult to drain (face, hand, genitalia)
     • Associated septic phlebitis
     • Lack of response to incision and drainage alone 1

Antibiotic Selection

If antibiotics are indicated, the following are recommended:

First-line options:

• Clindamycin (300-450 mg orally three times daily) 1, 2

  • Effective against both MRSA and streptococci
  • Duration: 5-10 days, individualized based on clinical response

• Trimethoprim-sulfamethoxazole (TMP-SMX) (1-2 double-strength tablets twice daily) 1

  • Effective against MRSA
  • May need to add a β-lactam (e.g., amoxicillin) if streptococcal coverage is also desired

• Cloxacillin (500 mg orally four times daily) 1, 3

  • Effective against methicillin-susceptible S. aureus (MSSA)
  • Duration: 5-10 days

• Cephalexin (500 mg orally four times daily) 1

  • Effective against MSSA and streptococci
  • Duration: 5-10 days

For suspected or confirmed MRSA:

• Doxycycline or minocycline (100 mg orally twice daily) 1
• Linezolid (600 mg orally twice daily) - reserved for more severe cases 1

Special Considerations

• Recurrent boils:

  • Obtain cultures to guide therapy 1
  • Consider a 5-day decolonization regimen with intranasal mupirocin, daily chlorhexidine washes, and decontamination of personal items 1
  • Evaluate for neutrophil disorders if recurrent abscesses began in early childhood 1

• Carbuncles (coalescent inflammatory mass with multiple draining points):

  • More aggressive treatment approach is needed
  • Incision and drainage plus antibiotics is typically required 1

Common Pitfalls to Avoid

1. Treating all boils with antibiotics: Most simple boils require only incision and drainage 1

2. Failing to culture: For recurrent or non-responding boils, obtain cultures to guide antibiotic therapy 1

3. Missing signs of systemic illness: Always assess for fever, tachycardia, tachypnea, and abnormal white blood cell count to determine if antibiotics are needed 1

4. Inadequate drainage: Ensure complete drainage of the boil; antibiotics alone are insufficient if drainage is needed 1

5. Not considering MRSA: In areas with high MRSA prevalence, empiric therapy should include MRSA coverage if antibiotics are indicated 1

Remember that the most recent guidelines emphasize that incision and drainage alone is often sufficient for simple boils, with antibiotics reserved for specific indications as outlined above 1.