What is the recommended treatment for an infected ingrown hair under the armpit?

Treatment for Infected Ingrown Hair Under the Armpit

For an infected ingrown hair under the armpit, incision and drainage followed by topical antibiotics is the recommended first-line treatment, with oral antibiotics reserved for cases with extensive surrounding cellulitis or systemic symptoms.

Initial Assessment and Management

Diagnosis

• An infected ingrown hair (folliculitis) presents as an inflamed papule or pustule around a hair follicle
• When infection extends deeper into subcutaneous tissue, it may form a furuncle (boil)
• Infected ingrown hairs in the armpit are typically caused by:
  • Staphylococcus aureus (most common)
  • Streptococcus species
  • Sometimes polymicrobial infections

First-Line Treatment

1. Incision and drainage for any fluctuant or abscess-like lesion 1

   • Make a small incision with a sterile needle or blade
   • Thoroughly evacuate the pus
   • Break up any loculations within the abscess cavity
   • Simply cover the surgical site with a dry dressing 1

2. Topical antimicrobial therapy 1, 2

   • Apply twice daily for at least 14 days:
     • Clindamycin solution (alcohol-free)
     • Erythromycin solution (alcohol-free)
     • Benzoyl peroxide
     • Chlorhexidine (0.1%)

3. Wound care

   • Clean the area with mild soap and water
   • Avoid alcohol-based products as they can worsen skin dryness 2
   • Apply warm compresses to promote drainage 1

When to Escalate Treatment

Oral Antibiotics

Systemic antibiotics are indicated if any of the following are present 1:

• Extensive surrounding cellulitis
• Fever or other systemic symptoms
• Multiple lesions
• Immunocompromised patient
• Failed local treatment

Recommended Oral Antibiotics:

• First-line: Dicloxacillin or cephalexin for methicillin-susceptible S. aureus 1
• If MRSA is suspected: Doxycycline, clindamycin, or trimethoprim-sulfamethoxazole (SMX-TMP) 1
• Duration: 7-10 days 1

Prevention of Recurrence

1. Hygiene measures 1, 2

   • Regular cleansing with pH-neutral, non-irritating soaps
   • Wear loose-fitting, cotton clothing
   • Change clothing daily
   • Avoid sharing personal items like razors or towels

2. Hair removal practices

   • Consider trimming hair instead of shaving
   • If shaving:
     • Use a clean, sharp razor
     • Shave in the direction of hair growth
     • Apply moisturizer after shaving

3. For recurrent infections 2

   • Consider 5-day decolonization regimen:
     • Intranasal mupirocin twice daily
     • Daily chlorhexidine washes
     • Daily decontamination of personal items

When to Seek Further Medical Attention

• No improvement after 48-72 hours of treatment
• Worsening pain, redness, or swelling
• Development of fever or other systemic symptoms
• Formation of multiple lesions
• Recurrent infections despite appropriate treatment

Important Caveats

• Gram stain and culture of pus from abscesses are recommended to guide antibiotic therapy, especially in recurrent cases 1
• Avoid prolonged use of topical steroids due to risk of skin atrophy 2
• For recurrent infections, evaluate for underlying conditions such as diabetes or immunosuppression

By following this treatment approach, most infected ingrown hairs in the armpit will resolve without complications. Proper incision and drainage is the cornerstone of treatment, with antibiotics reserved for more extensive or systemic infections.