What is the treatment for a cyst or boil on the armpit?

Treatment of Armpit Cysts and Boils

Incision and drainage is the primary and definitive treatment for both armpit boils (furuncles) and infected cysts, and antibiotics are generally not needed unless you have fever, rapid heart rate, or signs of spreading infection. 1

Initial Treatment Approach

For Simple Boils or Abscesses

• Perform incision and drainage as the cornerstone of treatment—this involves making an incision, thoroughly evacuating all pus, and probing the cavity to break up any pockets of infection 1, 2
• Simply cover the drained site with a dry sterile dressing after drainage—this is usually more effective and less painful than packing the wound with gauze 1
• Do NOT use antibiotics for simple boils or abscesses after adequate drainage if the patient appears well 1, 2

For Small Furuncles (Boils)

• Apply moist heat to promote spontaneous drainage for small lesions 1
• Larger furuncles require incision and drainage 1, 2

For Inflamed Cysts

• Incision and drainage is required for inflamed epidermoid cysts, which have essentially become abscesses 1, 2
• Do NOT obtain cultures from inflamed cysts—the inflammation is typically a reaction to cyst wall rupture rather than true infection 1

When to Add Antibiotics

Add antibiotics directed against Staphylococcus aureus only if ANY of the following are present: 1

• Systemic inflammatory response signs (SIRS):

  • Temperature >38°C (100.4°F) or <36°C (96.8°F)
  • Heart rate >90 beats per minute
  • Respiratory rate >24 breaths per minute
  • White blood cell count >12,000 or <4,000 cells/µL 1

• Other high-risk features:

  • Extensive surrounding cellulitis (redness extending >5 cm from the lesion) 1
  • Immunocompromised state (diabetes, HIV, chemotherapy, chronic steroids) 1
  • Multiple lesions 1
  • Failed initial drainage 1

Antibiotic Selection for Armpit Location

For axillary (armpit) abscesses specifically, use cefoxitin or ampicillin-sulbactam due to mixed flora from skin and adjacent areas 2

Alternative regimens if the above are unavailable:

• First-line for uncomplicated cases: Cephalexin 500 mg every 6-12 hours for skin infections 3
• If MRSA risk factors present (recent hospitalization, healthcare exposure, known MRSA carrier, failed initial therapy): Use trimethoprim-sulfamethoxazole, doxycycline, or clindamycin 1

Duration: Treat for 5-7 days based on clinical response 1, 2

Critical Pitfalls to Avoid

• Never attempt needle aspiration instead of incision and drainage—it has only a 25% success rate overall and <10% success with MRSA infections 1
• Do not prescribe antibiotics alone without drainage for fluctuant abscesses—this will fail as antibiotics cannot penetrate abscess cavities effectively 1, 2
• Do not culture uninflamed cysts—they normally contain skin flora even when not infected 1, 4
• Do not pack wounds routinely—studies show packing causes more pain without improving healing compared to simple dry dressing 1

For Recurrent Boils

If boils keep recurring in the armpit or elsewhere: 1

• Culture the abscess to identify the causative organism 1
• Consider a 5-day decolonization regimen:
  • Intranasal mupirocin twice daily
  • Daily chlorhexidine body washes
  • Daily laundering of towels, sheets, and clothes 1
• Treat with a 5-10 day course of antibiotics active against the cultured pathogen 1

Special Considerations

Large or complex abscesses (>5 cm, multiloculated, or with surrounding extensive cellulitis) may require:

• Multiple counter-incisions rather than one long incision to prevent scarring and delayed healing 2
• Broader antibiotic coverage including Gram-negative and anaerobic bacteria 2
• Possible surgical consultation for operative drainage 2