Duration of Cephalexin (Keflex) Treatment for Uncomplicated Cellulitis
For uncomplicated cellulitis, a 5-6 day course of cephalexin is as effective as a 10-day course if clinical improvement has occurred by day 5. 1, 2
Evidence-Based Treatment Duration
The most recent guidelines provide clear recommendations regarding the optimal duration of antibiotic therapy for uncomplicated cellulitis:
- The 2021 American College of Physicians (ACP) best practice advice recommends a shorter course of antibiotics (5-7 days) for uncomplicated cellulitis 1
- The 2014 Infectious Diseases Society of America (IDSA) guidelines state that a 5-day course is as effective as a 10-day course if clinical improvement has occurred by day 5 1
- The 2019 National Institute for Health and Care Excellence (NICE) guideline recommends a course of 5-7 days 1
Supporting Research Evidence
Several clinical trials support these shorter treatment durations:
- A randomized, double-blind, placebo-controlled trial comparing 5 days versus 10 days of levofloxacin therapy found no significant difference in clinical outcomes (98% success rate in both groups) 3
- Multiple systematic reviews have shown similar clinical responses between shorter (5-6 days) and longer (10-12 days) antibiotic courses 1
- The DANCE (Duration of Antibiotic Therapy for Cellulitis) RCT compared 6-day versus 12-day courses of flucloxacillin with similar rates of cure 1
Dosing Recommendations
For adults with uncomplicated cellulitis, the standard dosing of cephalexin is:
- 500 mg orally four times daily 2
- Alternative dosing: 500 mg every 12 hours 4
- Total daily dose should be within 1-4 grams 4
Special Considerations
When to Consider Extending Treatment
Treatment duration may need to be extended in the following situations:
- Lack of clinical improvement after 5 days 1
- Immunocompromised patients
- Severe or complicated infections
- Diabetic patients
MRSA Considerations
- MRSA is an unusual cause of typical cellulitis 1
- Standard beta-lactam therapy (like cephalexin) is appropriate for most cases of uncomplicated cellulitis 1
- Consider MRSA coverage only in specific situations:
- Cellulitis associated with penetrating trauma
- Illicit drug use
- Purulent drainage
- Concurrent evidence of MRSA infection elsewhere
- Failure to respond to beta-lactam therapy within 48-72 hours 2
Monitoring and Follow-up
- Patients should be reassessed within 48-72 hours of initiating therapy 2
- Consider changing therapy if no improvement or worsening occurs 2
- Instruct patients to complete the full prescribed course (5-6 days) even if symptoms improve quickly 2
Adjunctive Measures
- Elevation of the affected area to promote drainage of edema and inflammatory substances 1
- Address predisposing conditions (tinea pedis, trauma, venous eczema) 1
- Consider systemic corticosteroids in non-diabetic adult patients 1, 2
In conclusion, the most current evidence supports a 5-6 day course of cephalexin for uncomplicated cellulitis, provided there is clinical improvement by day 5. This shorter duration is as effective as traditional 10-day courses while reducing antibiotic exposure and potential side effects.