What can you give someone who is penicillin (PCN) allergic for streptococcal pharyngitis (strep throat)?

Treatment of Streptococcal Pharyngitis in Penicillin-Allergic Patients

For penicillin-allergic patients with strep throat, use first-generation cephalosporins (cephalexin or cefadroxil) if the allergy is non-anaphylactic, or clindamycin if the allergy is immediate/anaphylactic. 1

Treatment Algorithm Based on Allergy Type

Non-Anaphylactic Penicillin Allergy (No Immediate Hypersensitivity)

First-generation cephalosporins are the preferred first-line alternative:

• Cephalexin 20 mg/kg per dose twice daily for 10 days 1, 2
• Cefadroxil 30 mg/kg once daily for 10 days 1
• These have strong, high-quality evidence for efficacy and high success rates in eradicating streptococci 1

Critical caveat: Up to 10% of patients with immediate hypersensitivity to penicillin may have cross-reactivity with first-generation cephalosporins, so cephalosporins should be avoided in patients with anaphylactic reactions 1, 2

Immediate/Anaphylactic Penicillin Allergy

Three equally acceptable alternatives exist:

• Clindamycin 7 mg/kg per dose three times daily (maximum 300 mg per dose) for 10 days 1

  • Strong, moderate-quality evidence 1
  • Highly effective at eradicating streptococci, even in chronic carriers 1
  • Clindamycin resistance among Group A Streptococcus in the United States is approximately 1% 1

• Clarithromycin 7.5 mg/kg per dose twice daily (maximum 250 mg per dose) for 10 days 1

• Azithromycin 12 mg/kg once daily (maximum 500 mg) for 5 days 1, 3

  • The only antibiotic requiring just 5 days due to prolonged tissue half-life 1, 2
  • Important resistance concern: Macrolide resistance among Group A Streptococcus is approximately 5-8% in the United States, varying geographically 1, 2
  • Susceptibility testing should be performed when treating with azithromycin 3

Critical Duration Considerations

Most oral antibiotics require a full 10-day course to achieve maximal pharyngeal eradication of Group A Streptococcus 1, 2. Azithromycin is the sole exception at 5 days 1, 2.

Common pitfall to avoid: Prescribing shorter courses than recommended (except for azithromycin) leads to treatment failure and complications 1

Resistance Patterns and Local Considerations

• Be aware of local macrolide resistance patterns when prescribing azithromycin, clarithromycin, or erythromycin 1, 2
• In areas with high macrolide resistance, cephalexin is preferred for patients with severe penicillin allergy 1
• Clindamycin has the lowest resistance rate at approximately 1% 1

Adjunctive Therapy

• Acetaminophen or NSAIDs can be used for moderate to severe symptoms or high fever 1
• Avoid aspirin in children due to risk of Reye syndrome 1
• Corticosteroids are not recommended as adjunctive therapy 1

Special Populations

Recurrent streptococcal pharyngitis: Clindamycin may be particularly effective due to its ability to eradicate the organism in chronic carriers 1, 2

Common pitfall to avoid: Assuming all penicillin-allergic patients cannot receive cephalosporins—only those with immediate/anaphylactic reactions should avoid them 1