Repeat Course of Cephalexin (Keflex) for Infections
A repeat course of cephalexin (Keflex) is appropriate when the initial treatment course has not resolved the infection, but should be limited to specific indications and should not exceed the standard duration of 5-10 days per course depending on the infection type. 1
Indications for Repeat Cephalexin Treatment
Cellulitis
- Standard duration for uncomplicated cellulitis is 5-6 days 1
- Extend treatment if infection has not improved within this time period
- Signs indicating need for extended/repeat treatment:
- Persistent erythema, warmth, or swelling
- Continued fever or systemic symptoms
- Expanding area of infection
Streptococcal Pharyngitis
- Standard duration is 10 days for GAS pharyngitis 2
- Shorter courses (5 days) are not recommended for cephalexin in streptococcal pharyngitis 2
- A repeat course may be necessary if:
- Symptoms persist after completing full 10-day course
- Clinical failure is documented by positive follow-up culture
Urinary Tract Infections
- Standard duration is 5-7 days for uncomplicated UTIs 3
- Cephalexin is effective for UTIs at 500 mg twice daily or four times daily 3
- A repeat course may be indicated for:
- Persistent symptoms after completion of initial course
- Recurrent infection with susceptible organisms
Contraindications to Repeat Courses
- Known cephalexin resistance: Repeating cephalexin for organisms with documented resistance is ineffective 4
- Patients with immediate (anaphylactic-type) hypersensitivity to penicillin (up to 10% cross-reactivity) 2
- Failure of multiple previous courses (consider alternative antibiotics)
Duration of Repeat Treatment
The duration of repeat treatment should follow standard guidelines based on the infection type:
- Uncomplicated skin infections: 5-7 days 1
- Streptococcal pharyngitis: 10 days 2
- Respiratory tract infections: 7-10 days 1
- Uncomplicated UTIs: 5-7 days 3
Important Considerations
Antibiotic Stewardship
- Avoid unnecessary repeat courses to prevent development of resistance 1
- Consider culture and sensitivity testing before initiating a repeat course
- Narrow-spectrum cephalosporins like cephalexin are preferred over broad-spectrum options 2
Patient Factors
- Ensure patient completed the full initial course as prescribed
- Assess for underlying conditions that may contribute to treatment failure:
- Immunocompromise
- Foreign bodies
- Abscesses requiring drainage
- Underlying structural abnormalities
Alternative Options
If repeat cephalexin treatment fails:
- Consider alternative antibiotics based on likely pathogens and local resistance patterns
- For penicillin-allergic patients with streptococcal infections: clindamycin or macrolides 2
- For cellulitis with MRSA risk factors: consider MRSA-active agents 1
Common Pitfalls
- Inadequate initial treatment duration
- Failure to address predisposing factors
- Not considering resistant organisms after initial treatment failure
- Repeating the same antibiotic when culture shows resistance
- Not extending treatment when infection has not improved after standard duration 1
By following these guidelines, repeat courses of cephalexin can be used appropriately while minimizing the risk of antibiotic resistance and treatment failure.