Liquid Antibiotic Treatment for Streptococcal Pharyngitis
For a 20-kg child with strep throat, prescribe oral amoxicillin suspension 500 mg (25 mg/kg) twice daily for a full 10 days as first-line therapy. 1, 2
First-Line Liquid Antibiotic Regimen
Amoxicillin suspension is the preferred first-line treatment because of proven efficacy, excellent palatability in children, narrow antimicrobial spectrum, zero documented resistance worldwide, and low cost. 1, 2
Dosing options for a 20-kg child:
The complete 10-day course is mandatory to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever, even if symptoms resolve within 3–4 days. 1, 2
Liquid Alternatives for Penicillin Allergy
Non-Immediate (Delayed) Penicillin Allergy
First-generation cephalosporin suspensions are preferred alternatives with strong, high-quality evidence and only 0.1% cross-reactivity risk in delayed reactions. 1, 3
Cephalexin suspension: 400 mg (20 mg/kg) twice daily for 10 days (maximum 500 mg per dose). 1, 3
Cefadroxil suspension: 600 mg (30 mg/kg) once daily for 10 days (maximum 1 gram). 1, 3
Immediate/Anaphylactic Penicillin Allergy
All β-lactam antibiotics must be avoided because cross-reactivity can reach 10% in patients with immediate hypersensitivity reactions (anaphylaxis, angioedema, urticaria within 1 hour). 1, 3
Clindamycin solution: 140 mg (7 mg/kg) three times daily for 10 days (maximum 300 mg per dose) is the preferred non-β-lactam alternative with only ~1% resistance in the United States. 1, 3
Azithromycin suspension: 240 mg (12 mg/kg) once daily for 5 days (maximum 500 mg) is an acceptable alternative, but macrolide resistance ranges from 5–8% in the United States. 1, 3, 4
Clarithromycin suspension: 150 mg (7.5 mg/kg) twice daily for 10 days (maximum 250 mg per dose) shares similar resistance concerns as azithromycin. 1, 3
Azithromycin is the only antibiotic requiring just 5 days due to its prolonged tissue half-life; all other agents require the full 10-day course. 1, 3
Critical Pitfalls to Avoid
Do not shorten the antibiotic course below 10 days (except azithromycin's 5-day regimen), as this markedly increases treatment failure rates and rheumatic fever risk. 1, 2
Do not use cephalosporins in patients with immediate/anaphylactic penicillin reactions due to the ~10% cross-reactivity risk. 1, 3
Do not prescribe trimethoprim-sulfamethoxazole (Bactrim) for strep throat; it fails to eradicate Group A Streptococcus in 20–25% of cases. 1, 3
Do not use tetracyclines or fluoroquinolones for pediatric streptococcal pharyngitis due to high resistance rates and unnecessary broad-spectrum activity. 1, 2
Do not prescribe macrolides as first-line therapy when penicillin or amoxicillin can be used, as this unnecessarily broadens the spectrum and contributes to resistance. 3, 2
Adjunctive Symptomatic Management
Offer acetaminophen or ibuprofen for moderate-to-severe sore throat, fever, or systemic discomfort. 1, 2
Avoid aspirin in children because of the risk of Reye syndrome. 1, 2
Corticosteroids are not recommended as adjunctive therapy for streptococcal pharyngitis. 1, 3
Practical Liquid Formulation Guidance
Amoxicillin suspension is available in 125 mg/5 mL, 200 mg/5 mL, 250 mg/5 mL, and 400 mg/5 mL concentrations; for a 20-kg child receiving 500 mg twice daily, use the 400 mg/5 mL concentration (6.25 mL per dose) for convenience. 2
Azithromycin suspension is available in 100 mg/5 mL and 200 mg/5 mL concentrations; for a 20-kg child receiving 240 mg daily, use the 200 mg/5 mL concentration (6 mL per dose). 4
Clindamycin solution is available in 75 mg/5 mL concentration; for a 20-kg child receiving 140 mg three times daily, administer approximately 9.3 mL per dose. 1