What is the best treatment for a patient with an ingrown hair and signs of infection?

Treatment of Infected Ingrown Hair

For an ingrown hair with signs of infection, incision and drainage is the primary treatment, with adjunctive antibiotics reserved for patients with systemic signs of infection (fever, tachycardia, elevated WBC), extensive surrounding cellulitis, or immunocompromise. 1

Initial Assessment and Management

Determine Infection Severity

Evaluate for systemic inflammatory response syndrome (SIRS) criteria: 1

• Temperature >38°C or <36°C
• Tachycardia >90 beats per minute
• Tachypnea >24 breaths per minute
• White blood cell count >12,000 or <4,000 cells/µL

Primary Treatment: Incision and Drainage

Incision and drainage is the recommended treatment for furuncles (infected hair follicles) and abscesses. 1 This involves:

• Incising the lesion
• Thoroughly evacuating the pus
• Probing the cavity to break up loculations 1
• Covering with a simple dry sterile dressing (packing causes more pain without improving healing) 1

Antibiotic Therapy Decision Algorithm

When Antibiotics Are NOT Needed:

• Simple, localized infected ingrown hair without surrounding cellulitis 1
• No systemic signs of infection 1
• Normal immune function 1
• After adequate incision and drainage 1

When Antibiotics ARE Indicated:

Administer antibiotics active against S. aureus if any of the following are present: 1

• SIRS criteria met (see above)
• Extensive surrounding cellulitis 1
• Multiple lesions 1
• Markedly impaired host defenses (diabetes, immunosuppression) 1
• Fever or systemic symptoms 1

Antibiotic Selection

For Methicillin-Susceptible S. aureus (MSSA):

• Oral dicloxacillin 500 mg four times daily 1
• Cephalexin 500 mg four times daily 1
• For penicillin allergy: Clindamycin 300-400 mg three times daily 1

For Suspected MRSA (Community-Acquired):

Use MRSA-active antibiotics if: 1

• Local MRSA prevalence is high
• Patient has risk factors for MRSA
• Previous MRSA infection

Antibiotic options: 1

• Trimethoprim-sulfamethoxazole (1-2 double-strength tablets twice daily)
• Doxycycline 100 mg twice daily
• Clindamycin 300-450 mg three times daily (if susceptible)

Important caveat: Do not use trimethoprim-sulfamethoxazole as monotherapy if streptococcal cellulitis is possible, as streptococci are intrinsically resistant. 1

Culture Recommendations

• Culture is recommended for carbuncles and abscesses, though treatment without culture is reasonable in typical cases 1
• Always culture recurrent abscesses early in the course 1
• Culture guides antibiotic selection and identifies MRSA 1

Duration of Antibiotic Therapy

• 5-10 days for infected lesions requiring antibiotics 1
• Continue until clinical improvement is evident 1

Prevention of Recurrence

For patients with recurrent infected ingrown hairs, consider: 1

• 5-day decolonization regimen:
  • Intranasal mupirocin twice daily
  • Daily chlorhexidine body washes
  • Daily laundering of towels, sheets, and clothes

Common Pitfalls to Avoid

• Do not rely on needle aspiration instead of incision and drainage (only 25% success rate, <10% with MRSA) 1
• Do not pack wounds routinely after drainage—this increases pain without improving healing 1
• Do not prescribe antibiotics alone without drainage for abscesses—incision and drainage is essential 1
• Do not use trimethoprim-sulfamethoxazole alone if streptococcal infection is possible 1