Treatment of Strep Throat
Penicillin or amoxicillin for 10 days is the first-line treatment for strep throat in patients without penicillin allergy, due to proven efficacy, narrow spectrum, safety, and low cost. 1
First-Line Treatment for Non-Allergic Patients
For adults and adolescents, penicillin V 500 mg orally twice daily for 10 days is the recommended regimen 1. Alternative dosing of 250 mg four times daily is equally effective 1.
For children aged 3 months and older, amoxicillin is preferred over penicillin V due to better palatability and availability as suspension 1. The recommended dosing is:
- 50 mg/kg once daily (maximum 1,000 mg) for 10 days, OR 1
- 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1
For patients unlikely to complete a full 10-day oral course, intramuscular benzathine penicillin G as a single dose is recommended: 600,000 units for patients <27 kg (60 lb) and 1,200,000 units for patients ≥27 kg 1. This remains the preferred approach in populations where compliance cannot be assured, particularly in inner-city settings where rheumatic fever is still prevalent 2.
Treatment for Penicillin-Allergic Patients
Non-Anaphylactic Penicillin Allergy
First-generation cephalosporins are the preferred first-line alternatives with strong, high-quality evidence supporting their efficacy 3, 1. The cross-reactivity risk is only 0.1% in patients with non-severe, delayed penicillin reactions 3.
Recommended regimens:
- Cephalexin: 500 mg orally twice daily for 10 days (adults) or 20 mg/kg per dose twice daily (maximum 500 mg/dose) for 10 days (children) 3
- Cefadroxil: 1 gram orally once daily for 10 days (adults) or 30 mg/kg once daily (maximum 1 gram) for 10 days (children) 3
Immediate/Anaphylactic Penicillin Allergy
Patients with immediate hypersensitivity reactions (anaphylaxis, angioedema, respiratory distress, or urticaria within 1 hour) must avoid all beta-lactam antibiotics, including cephalosporins, due to up to 10% cross-reactivity risk 3.
Clindamycin is the preferred choice with strong, moderate-quality evidence and only ~1% resistance among Group A Streptococcus in the United States 3:
- Adults: 300 mg orally three times daily for 10 days 3
- Children: 7 mg/kg per dose three times daily (maximum 300 mg/dose) for 10 days 3
Alternative macrolide options (with 5-8% resistance rates in the US) 3:
- Azithromycin: 500 mg orally once daily for 5 days (adults) or 12 mg/kg once daily (maximum 500 mg) for 5 days (children) 3, 4
- Clarithromycin: 250 mg orally twice daily for 10 days (adults) or 7.5 mg/kg per dose twice daily (maximum 250 mg/dose) for 10 days (children) 3
Critical Treatment Duration Requirements
A full 10-day course is essential for all antibiotics except azithromycin to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever 3, 1, 5. Azithromycin requires only 5 days due to its prolonged tissue half-life 3, 4.
Shortening the course by even a few days results in appreciable increases in treatment failure rates and rheumatic fever risk 3. Treatment must be continued for at least 10 days for any infection caused by Streptococcus pyogenes to prevent acute rheumatic fever 5.
Diagnostic Confirmation
Testing is essential before prescribing antibiotics, as clinical features alone cannot reliably distinguish bacterial from viral pharyngitis 1, 6. A positive rapid antigen detection test (RADT) is diagnostic and does not require backup culture 1. However, backup throat culture is recommended for children and adolescents with negative RADT results 1.
Clinical features that increase suspicion for strep throat include sudden onset of sore throat, fever, tonsillar exudate, and tender anterior cervical lymphadenopathy 1, 6. Prominent cough suggests viral etiology 1, 6.
Adjunctive Symptomatic Treatment
Acetaminophen or NSAIDs (such as ibuprofen) should be considered for moderate to severe symptoms or high fever 3, 1. Aspirin must be avoided in children due to Reye syndrome risk 3, 1. Corticosteroids are not recommended 3, 1.
Common Pitfalls to Avoid
Do not use cephalosporins in patients with anaphylaxis, angioedema, or immediate urticaria to penicillin due to 10% cross-reactivity risk 3.
Do not prescribe azithromycin as first-line therapy - it should only be used when penicillin and preferred alternatives cannot be used, and local resistance patterns must be considered 3.
Do not prescribe broad-spectrum cephalosporins (cefaclor, cefuroxime, cefixime, cefdinir, cefpodoxime) when narrow-spectrum first-generation agents are appropriate, as they are more expensive and more likely to select for antibiotic-resistant flora 3.
Do not routinely perform post-treatment throat cultures for asymptomatic patients who have completed therapy 3, 1.
Do not treat without diagnostic confirmation, as 60% or more adults with sore throat are prescribed antibiotics despite only 10% having Group A Streptococcus 6.
Special Considerations for Treatment Failures
For patients who fail initial treatment or have recurrent infections, clindamycin demonstrates superior eradication rates in treatment failures and chronic carriers 3. Alternative regimens include amoxicillin-clavulanate (40 mg amoxicillin/kg/day in 3 doses for 10 days, maximum 2000 mg/day) or penicillin plus rifampin 3.
Consider whether the patient is a chronic carrier experiencing viral infections rather than true recurrent streptococcal infections 3, 7. Chronic carriers generally do not require treatment unless special circumstances exist, such as community outbreak of rheumatic fever or family history of rheumatic fever 3.