What is the recommended dose of Keflex (Cephalexin) for an infected inclusion cyst in an adult?

Cephalexin Dosing for Infected Inclusion Cyst in Adults

For an infected inclusion cyst in an adult, the recommended dose of cephalexin (Keflex) is 500 mg orally four times daily for 5-7 days. 1, 2

Treatment Algorithm

Primary Management

1. Surgical Intervention

   • Incision and drainage is the primary treatment for infected inclusion cysts 2
   • Irrigation of the wound and debridement of necrotic tissue are critical components of management

2. Antibiotic Therapy

   • First-line antibiotic: Cephalexin 500 mg orally four times daily (q6h) for 5-7 days 1, 2
   • Alternative dosing: 500 mg every 12 hours may be used for skin and skin structure infections 1

Alternative Antibiotics (for penicillin-allergic patients)

• Clindamycin 300-450 mg orally three times daily for 5-6 days 2
• Doxycycline 100 mg twice daily for 5-6 days (avoid in pregnant women and children under 8) 2

Special Considerations

MRSA Coverage

Consider MRSA coverage in patients with:

• Previous MRSA infection or colonization
• Injection drug use
• Systemic inflammatory response syndrome
• Failed initial antibiotic treatment
• Immunocompromised status 2

If MRSA is suspected, options include:

• Trimethoprim-sulfamethoxazole 1 double-strength tablet orally twice daily 3
• Doxycycline 100 mg twice daily 2

Severe Infections

For severe infections with systemic symptoms:

• Consider hospitalization for parenteral antibiotics 2
• Broader coverage may be needed with vancomycin plus either piperacillin-tazobactam, ampicillin-sulbactam, or a carbapenem 2

Monitoring and Follow-up

• Assess response within 72 hours of starting treatment
• If no improvement after 72 hours:
  • Reevaluate the need for drainage if not already performed
  • Consider changing antibiotic therapy
  • Obtain cultures if not previously done 2

Common Pitfalls to Avoid

1. Failing to perform adequate incision and drainage (the primary treatment)
2. Using inappropriate antibiotic dosing
3. Continuing antibiotics beyond 7 days for uncomplicated infections
4. Not considering local resistance patterns
5. Using doxycycline in pregnant women or children under 8 years 2

Clinical studies have demonstrated that cephalexin is effective for skin and skin structure infections, with cure rates of approximately 89% in clinically evaluable patients 4. The efficacy of cephalexin is comparable to other antibiotics used for skin infections, while maintaining a favorable safety profile.