A boil or furuncle is a deep-seated infection of the hair follicles with a walled-off collection of pus. A carbuncle is a
cluster of interconnected furuncles.


  • Bacterial infection with Staphylococcus aureus, leading to the collection of pus

Clinical features

  • Common in people with poor general health, diabetes, or the debilitated
  • Painful mass, warm, and tender
  • Swelling becomes fluctuant, may point after 3 days

Differential diagnosis

  • Acne
  • Epidermal cyst


  • Pus swab for Gram staining and C&S
  • If recurrent, check for diabetes mellitus and HIV infection


General measures

  • Intermittent warm compresses to allow lesion to point
  • Incise and drain when ready, then cover with dressing (pack cavity)


  • May be useful if instituted early and in carbuncles, lesions on face and in
    immunocompromised patients
  • Cloxacillin 250-500 mg every 6 hours before food for 5 days
    Child: 12.5-25 mg/kg per dose
  • OR in penicillin allergy patients, erythromycin 500 mg every 6 hours
    Child: 7.5 mg/kg per dose


  • Personal hygiene with use of antiseptic soap