Treatment of Strep Throat in Adults
First-Line Treatment: Penicillin or Amoxicillin
For adults with confirmed Group A streptococcal pharyngitis, penicillin V 500 mg twice daily or 250 mg four times daily for 10 days is the first-line treatment, with amoxicillin 500 mg twice daily for 10 days as an equally effective alternative. 1, 2
Why Penicillin Remains First-Line
- Penicillin has proven efficacy, safety, narrow spectrum, and low cost, with no documented resistance anywhere in the world 1, 2
- The full 10-day course is essential to prevent acute rheumatic fever, suppress complications (peritonsillar abscess, cervical lymphadenitis), and achieve maximal pharyngeal eradication 1, 2
- Amoxicillin offers comparable efficacy with the advantage of twice-daily dosing, improving compliance 1, 3
Intramuscular Option for Compliance Concerns
- For patients unlikely to complete oral therapy, benzathine penicillin G 1.2 million units intramuscularly as a single dose is preferred 1, 2
- This ensures compliance and has historically been the gold standard with the highest cure rates 4
Treatment for Penicillin-Allergic Patients
Algorithm Based on Allergy Type
The type of penicillin allergy determines which alternative is safest and most effective.
Non-Immediate (Non-Anaphylactic) Penicillin Allergy
First-generation cephalosporins are the preferred alternatives, with cephalexin 500 mg twice daily for 10 days having strong, high-quality evidence. 1, 5, 6
- Cross-reactivity risk is only 0.1% in patients with non-severe, delayed penicillin reactions 2, 6
- Cefadroxil 1 gram once daily for 10 days is an alternative with once-daily convenience 1, 5
- Do not use cephalosporins in patients with immediate hypersensitivity reactions (anaphylaxis, angioedema, urticaria within 1 hour) due to up to 10% cross-reactivity risk 1, 6
Immediate/Anaphylactic Penicillin Allergy
Clindamycin 300 mg three times daily for 10 days is the preferred choice for immediate penicillin allergy, with only 1% resistance among Group A Streptococcus in the United States. 1, 5, 6
- Clindamycin demonstrates superior eradication rates even in chronic carriers and treatment failures 5, 6
- All beta-lactams including cephalosporins must be avoided in this group 1, 6
Alternative macrolides include:
- Azithromycin 500 mg on day 1, then 250 mg daily for days 2-5 (total 5 days) 1, 5, 7
- Clarithromycin 250 mg twice daily for 10 days 1, 5
Critical Macrolide Resistance Considerations
Macrolide resistance among Group A Streptococcus is 5-8% in the United States but varies geographically, making clindamycin more reliable than azithromycin or clarithromycin when beta-lactams cannot be used. 1, 5, 6
- Azithromycin is the only antibiotic requiring just 5 days due to its prolonged tissue half-life 1, 5, 7
- Macrolides should be reserved for patients with documented immediate penicillin allergy who cannot use clindamycin 5, 2
- Check local resistance patterns before prescribing macrolides—resistance can be much higher than 5-8% in some areas 1, 6
Treatment Duration: Non-Negotiable
All antibiotics except azithromycin require a full 10-day course to achieve maximal pharyngeal eradication and prevent acute rheumatic fever. 1, 5, 2, 6
- Shortening the course by even a few days dramatically increases treatment failure rates and rheumatic fever risk 2, 6
- Therapy can be safely postponed up to 9 days after symptom onset and still prevent acute rheumatic fever 6
- Patients become non-contagious after 24 hours of appropriate antibiotic therapy 5
Common Pitfalls to Avoid
Do not prescribe broad-spectrum cephalosporins (cefdinir, cefpodoxime, cefixime) when narrow-spectrum first-generation agents are appropriate—they are more expensive and select for resistant flora 6
Do not assume all penicillin-allergic patients need macrolides—most can safely receive first-generation cephalosporins if the allergy is non-immediate 6
Do not use trimethoprim-sulfamethoxazole (Bactrim) for strep throat—resistance rates are 50% and it is not recommended for Group A Streptococcus 5
Do not routinely perform post-treatment throat cultures—they are not recommended for asymptomatic patients who completed therapy unless special circumstances exist (history of rheumatic fever, community outbreak) 5, 2
Adjunctive Symptomatic Treatment
- Acetaminophen or NSAIDs (ibuprofen) for moderate to severe symptoms or high fever 6
- Avoid aspirin in children due to Reye syndrome risk 6
- Corticosteroids are not recommended 6
Special Scenario: Treatment Failures or Chronic Carriers
For patients who fail initial therapy or are chronic carriers requiring eradication, clindamycin 300 mg three times daily for 10 days demonstrates substantially higher eradication rates than penicillin or amoxicillin. 5, 6