What is the recommended amoxicillin (amoxicillin) dose for a child with suspected bacterial tonsillitis?

Amoxicillin Dosing for Pediatric Bacterial Tonsillitis

For a child with suspected bacterial tonsillitis (Group A Streptococcal pharyngitis), prescribe high-dose amoxicillin at 50 mg/kg once daily (maximum 1000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) for a full 10-day course. 1

Dosing Regimen

• Standard dosing: Amoxicillin 50 mg/kg/day given once daily (maximum 1000 mg/day) OR 25 mg/kg twice daily (maximum 500 mg per dose) 1
• Alternative twice-daily dosing: 45 mg/kg/day divided into 2 doses for mild-to-moderate infections 2
• Maximum daily dose: Do not exceed 1000 mg/day for once-daily dosing or 500 mg per dose for twice-daily dosing in standard tonsillitis cases 1

Treatment Duration

• Complete the full 10-day course even if symptoms resolve earlier to prevent acute rheumatic fever and reduce recurrence risk 1, 3
• Treatment should continue for at least 48-72 hours beyond symptom resolution 3
• The 10-day duration is critical for Group A Streptococcus eradication and prevention of complications 3

When Amoxicillin Alone May Not Be Appropriate

While amoxicillin is first-line for uncomplicated strep throat, amoxicillin-clavulanate (Augmentin) should be reserved for treatment failures or chronic carriers 1. The evidence shows that:

• Amoxicillin-clavulanate at 40 mg/kg/day (amoxicillin component) divided into 2-3 doses (maximum 2000 mg/day) is effective for recurrent cases 1
• Beta-lactamase-producing bacteria in the tonsils can "shield" Group A Streptococcus from penicillin, explaining some treatment failures 4
• Amoxicillin-clavulanate demonstrated 83% long-term eradication rates in comparative studies 5

Penicillin Allergy Alternatives

For children with documented penicillin allergy:

• Cephalexin (if no severe/anaphylactic penicillin allergy) 1
• Clindamycin for severe penicillin reactions 1
• Azithromycin 10 mg/kg on day 1, then 5 mg/kg/day for days 2-5 (maximum 500 mg day 1,250 mg days 2-5) 6

Important caveat: Macrolides like azithromycin should be avoided in areas with high macrolide resistance rates, as bacteriologic failure occurs in 81-86% of clarithromycin-resistant isolates 5. Amoxicillin-clavulanate and penicillin V are bacteriologically superior to macrolides when resistance is present 5.

Administration Instructions

• Give at the start of meals to minimize gastrointestinal intolerance 3
• For oral suspension, shake well before each use 3
• Suspension can be mixed with formula, milk, fruit juice, water, or cold drinks and consumed immediately 3
• Refrigerate reconstituted suspension (preferred but not required); discard after 14 days 3

Monitoring Response

• Expect clinical improvement within 48-72 hours of starting therapy 6, 2
• If symptoms worsen or fail to improve within 48-72 hours, reevaluate for complications or alternative diagnoses 6
• Consider treatment failure if no response by 72 hours and switch to amoxicillin-clavulanate or alternative agent 1

Common Pitfalls to Avoid

• Non-compliance with 10-day regimen: This is the primary cause of treatment failure, with bacteriologic failure rates increasing from 2-10% historically to approximately 30% when courses are shortened 7
• Premature discontinuation: Stopping antibiotics when symptoms resolve (typically 3-5 days) increases risk of rheumatic fever and recurrence 3
• Using macrolides as first-line: Reserve azithromycin for penicillin-allergic patients only, as resistance patterns make it less reliable for eradication 5
• Underdosing: Ensure weight-based dosing is calculated correctly, particularly in younger children where 50 mg/kg may be needed 1