Alternative Antibiotic for Paronychia with Bactrim Intolerance
Switch to cephalexin 500 mg four times daily for 7 days as your first-line alternative for paronychia when gastrointestinal upset prevents Bactrim use. 1
Rationale for Cephalexin
Cephalexin is the optimal alternative because:
First-generation cephalosporins like cephalexin provide excellent coverage against the typical pathogens causing paronychia (Staphylococcus aureus and beta-hemolytic streptococci), which are the primary organisms in this infection 1
IDSA guidelines specifically recommend cephalexin as a first-line oral agent for skin and soft tissue infections when MRSA is not suspected 1
Cephalexin has significantly better gastrointestinal tolerability than Bactrim, with GI side effects occurring in only 4-15% of patients compared to the higher rates seen with trimethoprim-sulfamethoxazole 2
The drug achieves excellent tissue penetration in skin and soft tissue infections, making it ideal for paronychia 2
Dosing Regimen
Standard dose: 500 mg orally four times daily (every 6 hours) for 7 days 1
Alternative if compliance is a concern: Cefadroxil 500 mg twice daily, which has equivalent MIC values to cephalexin but allows less frequent dosing due to its longer half-life 3
When to Consider Other Alternatives
If MRSA is suspected (prior MRSA infection, recent hospitalization, or treatment failure):
Clindamycin 300-600 mg orally three times daily is the preferred alternative, as it covers both streptococci and community-acquired MRSA 1, 4
Doxycycline 100 mg twice daily is another option with MRSA coverage, though it causes more GI upset than cephalexin 1
If the patient has a beta-lactam allergy:
Clindamycin remains the best choice at 300-600 mg three times daily 1, 4
Avoid fluoroquinolones for simple paronychia as they are unnecessarily broad-spectrum 1
Treatment Duration and Monitoring
7 days of therapy is appropriate for uncomplicated paronychia 1
Clinical improvement should be evident within 3-4 days (decreased erythema, swelling, and tenderness) 1
If no improvement by day 3-4, consider incision and drainage if not already performed, or reassess for MRSA coverage 1
Important Clinical Pearls
Incision and drainage is the primary treatment for paronychia with abscess formation; antibiotics are adjunctive 1
Simple paronychia without systemic symptoms may respond to drainage alone, but antibiotics reduce recurrence and spread 1
Cephalexin does NOT cover MRSA, so if the patient fails to improve on cephalexin, switch to clindamycin or add trimethoprim-sulfamethoxazole if GI symptoms have resolved 1, 5
The combination of cephalexin plus trimethoprim-sulfamethoxazole provides both streptococcal and MRSA coverage if you need to restart Bactrim later once GI symptoms resolve 5