Treatment for Streptococcal Pharyngitis
Penicillin or amoxicillin for 10 days remains the definitive first-line treatment for strep throat due to proven efficacy, safety, narrow spectrum, and low cost. 1, 2
First-Line Treatment Options
For patients without penicillin allergy:
Oral penicillin V is the gold standard: 250 mg four times daily or 500 mg twice daily for adolescents/adults; 250 mg two to three times daily for children, always for 10 days 1, 2
Oral amoxicillin is equally effective and more palatable: 50 mg/kg once daily (maximum 1,000 mg) or 25 mg/kg twice daily (maximum 500 mg) for 10 days 1, 2, 3
Intramuscular benzathine penicillin G (single dose) is preferred when compliance is questionable: 600,000 units for patients <27 kg; 1,200,000 units for patients ≥27 kg 1, 2
The 10-day duration is non-negotiable—this is the only regimen proven to prevent acute rheumatic fever, which requires complete bacterial eradication 1, 2. Shortening the course by even a few days significantly increases treatment failure rates 1, 4.
For Patients with Penicillin Allergy
The type of allergic reaction determines safe alternatives:
Non-Immediate/Non-Anaphylactic Allergy (delayed rash, mild reactions):
- First-generation cephalosporins are preferred: Cephalexin 500 mg twice daily for adults (20 mg/kg/dose twice daily for children) or cefadroxil 30 mg/kg once daily for 10 days 1, 2, 4
- Cross-reactivity risk is only 0.1% with non-severe delayed reactions 4
Immediate/Anaphylactic Allergy (hives, angioedema, bronchospasm within 1 hour):
Clindamycin is the preferred choice: 300 mg three times daily for adults (7 mg/kg/dose three times daily for children, maximum 300 mg/dose) for 10 days 1, 2, 4
Clindamycin has ~1% resistance rate in the US and high efficacy even in chronic carriers 1, 4
Azithromycin is acceptable but less preferred: 500 mg once daily for adults (12 mg/kg once daily for children, maximum 500 mg) for 5 days only 1, 2, 4
Macrolide resistance is 5-8% in the US and varies geographically 1, 4, 5
Azithromycin requires only 5 days due to prolonged tissue half-life 1, 4
Clarithromycin is an alternative: 250 mg twice daily for adults (7.5 mg/kg/dose twice daily for children, maximum 250 mg/dose) for 10 days 2, 4
Diagnostic Confirmation Before Treatment
Testing is essential—clinical features alone cannot reliably distinguish strep from viral pharyngitis: 1, 2
Rapid antigen detection test (RADT) is first-line: A positive result is diagnostic and treatment can begin immediately 1, 2
Backup throat culture is required for negative RADT in children and adolescents (not adults) due to lower RADT sensitivity 1, 2
Clinical features suggesting strep: Sudden onset sore throat, fever >100.4°F, tonsillar exudates, tender anterior cervical lymphadenopathy, absence of cough/rhinorrhea 2, 6, 7
Adjunctive Symptomatic Treatment
Critical Pitfalls to Avoid
Do not use cephalosporins in patients with immediate/anaphylactic penicillin reactions—up to 10% cross-reactivity risk exists 1, 2, 4
Do not shorten the antibiotic course below 10 days (except azithromycin's 5-day regimen)—this dramatically increases treatment failure and rheumatic fever risk 1, 2, 8
Do not prescribe antibiotics without diagnostic confirmation—60% of adults with sore throat receive unnecessary antibiotics when only 10% have strep 7
Do not use trimethoprim-sulfamethoxazole (Bactrim)—it has 50% resistance rates against Group A Streptococcus and is not effective 4
Do not routinely perform post-treatment throat cultures in asymptomatic patients who completed therapy—testing is only indicated for special circumstances like history of rheumatic fever 1, 2
Special Considerations for Treatment Failure
If symptoms worsen after 48-72 hours of appropriate antibiotics or persist beyond 5 days: 2, 7
Retreat with the same antibiotic if compliance was good 1
Use intramuscular benzathine penicillin G if oral compliance is questionable 1
Consider clindamycin or amoxicillin-clavulanate for chronic carriers with recurrent episodes 1, 2
Chronic carriers (asymptomatic with positive cultures) generally do not require treatment—they are at low risk for transmission or complications 4, 6