Amoxicillin Dosing for Streptococcal Pharyngitis

Weight-Based Dosing Calculation

• The Infectious Diseases Society of America (IDSA) guideline recommends 50 mg/kg once daily (maximum 1000 mg) for children with streptococcal pharyngitis 1, 2
• For a patient weighing 59.87 kg, the calculated dose is 50 mg/kg × 59.87 kg = 2993.5 mg, which exceeds the maximum dose of 1000 mg 1
• Therefore, the maximum dose of 1000 mg once daily should be used 1, 2

Alternative Dosing Regimen

• The twice-daily alternative is 25 mg/kg twice daily, which calculates to approximately 1497 mg/day for a patient weighing 59.87 kg 1
• This also exceeds the maximum, so 500 mg twice daily (1000 mg total daily dose) should be used 1, 2
• Both once-daily and twice-daily regimens have strong, high-quality evidence for efficacy 1, 2

Critical Treatment Duration

• A full 10-day course is mandatory to prevent acute rheumatic fever, regardless of symptom resolution 1, 2

Common Pitfalls to Avoid

• Do not underdose: using pediatric weight-based calculations without applying the maximum cap would be incorrect 1
• Do not shorten the course: the full 10-day course is essential for preventing rheumatic fever 2
• Do not use azithromycin as first-line: penicillin or amoxicillin remains the drug of choice due to narrow spectrum, low cost, and lack of resistance 1, 2