Amoxicillin Dosing for Strep Throat in Children
For Group A Streptococcal pharyngitis (strep throat) in children, the safe and recommended daily dose of amoxicillin is 50-75 mg/kg/day divided into 2 doses for 10 days, with a maximum of 1000 mg per dose. 1
Standard Dosing Framework
The Infectious Diseases Society of America and American Heart Association recommend 50-75 mg/kg/day divided into 2 doses (given every 12 hours) for Group A Streptococcal infections in children. 1
The FDA label specifies that for ear/nose/throat infections (which includes strep pharyngitis) in children ≥3 months and <40 kg, mild to moderate infections require 25 mg/kg/day divided every 12 hours, while severe infections require 45 mg/kg/day divided every 12 hours. 2
However, for strep throat specifically, the higher dosing range of 50-75 mg/kg/day is preferred to ensure adequate bacterial eradication and prevent complications such as acute rheumatic fever. 1
Critical Treatment Duration
Treatment must continue for a full 10 days to prevent acute rheumatic fever, regardless of symptom resolution. 2
The FDA label explicitly states that at least 10 days of treatment is required for any infection caused by Streptococcus pyogenes (Group A Strep). 2
Children become non-contagious after 24 hours of antibiotic therapy, but the full course must be completed. 1
Practical Dosing Examples
For a child weighing 20 kg: 50 mg/kg/day = 1000 mg/day, given as 500 mg twice daily (every 12 hours). 1
The maximum single dose should not exceed 1000 mg per administration. 1
Amoxicillin should be taken at the start of a meal to minimize gastrointestinal side effects. 2
Special Populations
For infants <3 months old: The maximum dose is 30 mg/kg/day divided every 12 hours due to immature renal function, though strep pharyngitis is rare in this age group. 2
For children with severe renal impairment (GFR <30 mL/min): Dose adjustment is required, with dosing intervals extended to every 12-24 hours depending on severity. 2
Why This Dosing Matters
Research demonstrates that amoxicillin at 40-50 mg/kg/day achieves significantly better clinical cure (87.9% vs 70.9%) and bacteriologic cure (79.3% vs 54.5%) compared to lower-dose penicillin V regimens. 3
The 50-75 mg/kg/day dosing range ensures adequate middle ear fluid and tissue penetration to eradicate Group A Streptococcus effectively. 1
Common Pitfalls to Avoid
Do not use amoxicillin/clavulanate (Augmentin) as first-line therapy for uncomplicated strep throat - it is reserved for treatment failures or chronic carriers. 4
Do not prescribe shorter courses - even though symptoms may resolve in 2-3 days, the full 10-day course is mandatory to prevent rheumatic fever. 2
Do not underdose - the perception that penicillins are losing effectiveness may actually reflect inadequate dosing rather than true resistance. 3
Monitoring and Follow-Up
Children should show clinical improvement within 48-72 hours of starting therapy. 1
If no improvement occurs within this timeframe, reevaluation is necessary to assess for complications or alternative diagnoses. 1
The most common adverse effects include gastrointestinal disturbances (diarrhea, nausea, vomiting) and hypersensitivity reactions (rash, urticaria). 1