Antibiotic Treatment for Strep Throat in Adults
First-Line Therapy
Penicillin V 500 mg orally twice daily for 10 days is the drug of choice for otherwise healthy adults with confirmed group A streptococcal pharyngitis. 1
- Penicillin V has proven efficacy, a narrow antimicrobial spectrum, an excellent safety profile, low cost, and there is no documented penicillin resistance in Streptococcus pyogenes worldwide. 1
- Alternative dosing of penicillin V 250 mg four times daily for 10 days is equally effective but less convenient. 1
- Amoxicillin 500 mg orally twice daily for 10 days is an acceptable alternative (or 1000 mg once daily), offering better palatability and once-daily dosing options. 1
Critical Treatment Duration
- A full 10-day course is mandatory to achieve maximal pharyngeal eradication of S. pyogenes and to prevent acute rheumatic fever, even if symptoms resolve within 3–4 days. 1
- Shortening the course by even a few days results in appreciable increases in treatment failure rates and rheumatic fever risk. 1
When Adherence Is Uncertain
- Single-dose intramuscular benzathine penicillin G (1.2 million units) is an acceptable alternative when adherence to a 10-day oral regimen cannot be assured. 1
Treatment for Penicillin-Allergic Patients
Non-Immediate (Delayed) Reactions
For adults with a history of delayed, non-severe penicillin reactions (e.g., mild rash days after exposure), first-generation cephalosporins are the preferred alternatives.
- Cephalexin 500 mg orally twice daily for 10 days is the recommended first-generation cephalosporin. 1
- Cefadroxil 1 g orally once daily for 10 days is an acceptable alternative. 1
- The cross-reactivity risk with first-generation cephalosporins in patients with delayed, non-severe penicillin reactions is approximately 0.1%. 1
Immediate (Anaphylactic) Reactions
For adults with immediate hypersensitivity to penicillin (anaphylaxis, angioedema, urticaria within 1 hour, bronchospasm), all β-lactam antibiotics must be avoided.
- Clindamycin 300 mg orally three times daily for 10 days is the preferred non-β-lactam option. 1
- Clindamycin resistance among S. pyogenes in the United States is approximately 1%, and efficacy is high even in chronic carriers. 1
- Azithromycin 500 mg on day 1, then 250 mg daily on days 2–5 (total 5 days) is an acceptable alternative, but macrolide resistance in the United States ranges from 5–8% and varies geographically. 1
- Clarithromycin 250 mg orally twice daily for 10 days is another macrolide option with similar resistance concerns. 1
- Azithromycin is the only antibiotic for strep throat that can be given for 5 days because of its prolonged tissue half-life; all other agents require a full 10-day course. 1
Critical Pitfalls to Avoid
- Do not shorten the antibiotic course below 10 days (except the 5-day azithromycin regimen), as this markedly increases treatment-failure rates and the risk of acute rheumatic fever. 1
- Do not prescribe cephalosporins to patients with immediate/anaphylactic penicillin reactions because of the approximately 10% cross-reactivity risk. 1
- Do not use trimethoprim-sulfamethoxazole (Bactrim) for strep throat, as sulfonamides fail to eradicate Group A Streptococcus in 20–25% of cases. 2
- 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. 2
Adjunctive Symptomatic Treatment
- Acetaminophen or non-steroidal anti-inflammatory drugs (e.g., ibuprofen) may be used for moderate to severe symptoms or high fever. 1
- Corticosteroids are not recommended as adjunctive therapy for strep throat. 1