Treatment of Strep Throat
Penicillin V remains the definitive first-line treatment for strep throat, given orally for a full 10 days, due to its proven efficacy in preventing rheumatic fever, complete absence of resistance, narrow spectrum, safety profile, and low cost. 1, 2, 3
First-Line Antibiotic Treatment
Penicillin V is the treatment of choice for all patients without penicillin allergy:
- Children: 250 mg orally 2-3 times daily for 10 days 1, 2
- Adolescents and adults: 250 mg orally 4 times daily OR 500 mg twice daily for 10 days 1, 2
- Amoxicillin is an equally effective alternative with better palatability, particularly useful in young children: 50 mg/kg once daily (maximum 1000 mg) for 10 days 1, 2, 3
- Intramuscular benzathine penicillin G should be used when oral compliance is questionable: 600,000 units for patients <60 lbs (27 kg) or 1,200,000 units for patients ≥60 lbs as a single injection 1, 2
Group A streptococci have shown no resistance to penicillin over five decades of use, making it uniquely reliable 2. The full 10-day course is essential—shortening by even a few days significantly increases treatment failure rates and risk of acute rheumatic fever 1, 2, 3.
Treatment for Penicillin-Allergic Patients
The type of penicillin allergy determines which alternative is safe:
Non-Immediate (Non-Anaphylactic) Penicillin Allergy
First-generation cephalosporins are the preferred alternatives with only 0.1% cross-reactivity risk in delayed reactions 4:
- Cephalexin: 20 mg/kg per dose twice daily (maximum 500 mg per dose) for 10 days 1, 4
- Cefadroxil: 30 mg/kg once daily (maximum 1 gram) for 10 days 1, 4
These have strong, high-quality evidence for efficacy and maintain a narrow spectrum 1, 4.
Immediate/Anaphylactic Penicillin Allergy
All beta-lactam antibiotics must be avoided due to up to 10% cross-reactivity risk 4. Use these alternatives:
Clindamycin (preferred): 7 mg/kg per dose three times daily (maximum 300 mg per dose) for 10 days 1, 2, 4
Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1, 2, 4
Clarithromycin: 7.5 mg/kg per dose twice daily (maximum 250 mg per dose) for 10 days 1, 2, 4
- Similar resistance concerns as azithromycin 4
Critical Treatment Duration Requirements
A full 10-day course is mandatory for all antibiotics except azithromycin to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever 1, 2, 4, 3. Even shortening the course by a few days results in appreciable increases in treatment failure 1, 2. Therapy can be safely postponed up to 9 days after symptom onset and still prevent rheumatic fever 4.
Symptomatic Treatment
Adjunctive therapy should focus on symptom relief:
- Acetaminophen or NSAIDs (ibuprofen) for moderate to severe symptoms or high fever 1, 2, 4
- Never use aspirin in children due to Reye syndrome risk 1, 2, 4
- Corticosteroids are not recommended for routine treatment 1, 2, 4
- Adequate hydration and rest are important supportive measures 2
Diagnosis Confirmation
Throat culture remains the diagnostic standard, though rapid antigen detection testing is acceptable for clinical decision-making 1. However, for drug evaluation purposes, throat culture confirmation is required due to variable sensitivity (60-95%) and specificity (>90%) of rapid tests 1.
Common symptoms include sudden onset of sore throat, fever >100.4°F (38°C), tonsillar exudates, and tender anterior cervical adenopathy 2, 6. Viral features like cough, coryza, hoarseness, and conjunctivitis suggest against strep throat 1, 2.
Common Pitfalls to Avoid
Do not use cephalosporins in patients with immediate/anaphylactic penicillin reactions due to 10% cross-reactivity risk—this is a critical safety error 4.
Do not prescribe courses shorter than 10 days (except azithromycin's 5-day regimen) as this dramatically increases treatment failure and rheumatic fever risk 1, 2, 4.
Do not use trimethoprim-sulfamethoxazole (Bactrim) for strep throat—it has 50% resistance rates and cannot reliably achieve bactericidal eradication needed to prevent rheumatic fever 4.
Do not routinely test or treat asymptomatic patients after completing therapy—post-treatment cultures are not recommended for patients who successfully completed treatment 2, 3.
Chronic carriers generally do not require treatment as they are at low risk of complications or transmission 2, 6. Treatment may be considered only in specific outbreak situations or when there is excessive anxiety 1.
Special Considerations for High-Risk Populations
In areas where rheumatic fever remains prevalent (poor, crowded inner-city populations, low-income countries, Aboriginal communities) where compliance cannot be assured, intramuscular benzathine penicillin G is strongly preferred over oral therapy 7, 8. This ensures complete treatment and prevents the serious sequelae of inadequate therapy 7.