What can a patient take for strep throat if they are allergic to amoxicillin (amoxicillin)?

Treatment of Strep Throat in Amoxicillin-Allergic Patients

For patients with non-anaphylactic amoxicillin allergy, first-generation cephalosporins (cephalexin or cefadroxil) are the preferred first-line alternatives; for those with immediate/anaphylactic reactions, clindamycin is the treatment of choice. 1

Treatment Algorithm Based on Allergy Type

Non-Immediate/Non-Anaphylactic Allergy

If the patient's amoxicillin allergy involves delayed reactions (rash appearing days later, mild urticaria without respiratory symptoms), first-generation cephalosporins are safe and highly effective:

• Cephalexin 20 mg/kg per dose twice daily (maximum 500 mg/dose) for 10 days 1
• Cefadroxil 30 mg/kg once daily (maximum 1 gram) for 10 days 1
• These have strong, high-quality evidence for efficacy and carry only minimal cross-reactivity risk in non-immediate allergies 2, 1

Immediate/Anaphylactic Allergy

If the patient experienced anaphylaxis, angioedema, severe urticaria within minutes to hours, or has documented IgE-mediated allergy, avoid all beta-lactams including cephalosporins due to up to 10% cross-reactivity risk 2, 1:

• Clindamycin 7 mg/kg per dose three times daily (maximum 300 mg/dose) for 10 days is the preferred choice 1, 3

  • Clindamycin has strong, moderate-quality evidence and demonstrates high efficacy even in chronic carriers 1
  • Resistance is only approximately 1% in the United States, making it highly reliable 3

• Azithromycin 12 mg/kg once daily (maximum 500 mg) for 5 days is an acceptable alternative 2, 1

  • Requires only 5 days due to prolonged tissue half-life 2, 1
  • However, macrolide resistance is 5-8% in the United States and varies geographically 1, 3

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

  • Has strong, moderate-quality evidence but shares macrolide resistance concerns 1

Critical Treatment Duration Requirements

All antibiotics except azithromycin require a full 10-day course to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever. 2, 1 Shortening the course by even a few days results in appreciable increases in treatment failure rates 1. Azithromycin is the only exception, requiring only 5 days due to its unique pharmacokinetics 2, 1.

Important Caveats and Common Pitfalls

• Do not assume all penicillin-allergic patients cannot receive cephalosporins - only those with immediate/anaphylactic reactions should avoid them 1
• Be aware of local macrolide resistance patterns before prescribing azithromycin or clarithromycin, as resistance varies geographically and can lead to treatment failure 1, 3
• Clindamycin is more reliable than macrolides in areas with resistance concerns due to its 1% resistance rate versus 5-8% for macrolides 3
• Do not use trimethoprim-sulfamethoxazole - it has high resistance rates (50%) and is not recommended for Group A Streptococcus 1

Adjunctive Therapy

• Acetaminophen or NSAIDs (ibuprofen) can be used for moderate to severe symptoms or high fever 1, 3
• Avoid aspirin in children due to risk of Reye syndrome 1, 3
• Corticosteroids are not recommended as adjunctive therapy 1, 3

Post-Treatment Considerations

• Routine follow-up throat cultures are not recommended for asymptomatic patients who have completed therapy 2, 1
• Testing should only be considered in special circumstances, such as patients with a history of rheumatic fever 1