Amoxicillin Dosing for a 28 kg Child, Three Times Daily
For a 28 kg child requiring three-times-daily amoxicillin dosing, prescribe 260-350 mg per dose (approximately 28-37.5 mg/kg/day total), given every 8 hours for most mild to moderate infections. 1
Standard Dosing Framework
The appropriate dose depends critically on the indication and severity:
For Mild to Moderate Infections (Ear/Nose/Throat, Skin, Genitourinary)
- Dose: 20 mg/kg/day divided every 8 hours 1
- For this 28 kg child: 186 mg per dose, three times daily (total 560 mg/day)
- This aligns with FDA labeling for standard infections 1
For Severe Infections or Lower Respiratory Tract Infections
- Dose: 40 mg/kg/day divided every 8 hours 1
- For this 28 kg child: 373 mg per dose, three times daily (total 1,120 mg/day)
- This provides adequate coverage for pneumonia and severe infections 1
For Group A Streptococcal Infections (Strep Throat, Scarlet Fever)
- Dose: 50-75 mg/kg/day divided into 2-3 doses 2, 3
- For this 28 kg child: If using three-times-daily dosing: 467-700 mg per dose (total 1,400-2,100 mg/day)
- However, twice-daily dosing is strongly preferred for strep infections (see below) 3, 4
Critical Consideration: Twice-Daily Dosing is Preferred
The three-times-daily regimen is outdated for most pediatric infections. Current guidelines strongly favor twice-daily dosing because:
- Improved adherence: Twice-daily dosing significantly improves compliance compared to three-times-daily regimens 4
- Equivalent efficacy: 45-90 mg/kg/day divided every 12 hours provides comparable or superior outcomes 3, 4
- Better taste and tolerability: Modern formulations with twice-daily dosing are better accepted 3
Recommended Alternative (Twice-Daily Dosing)
For this 28 kg child:
- Mild to moderate infections: 315 mg twice daily (22.5 mg/kg/dose = 45 mg/kg/day total) 3, 4
- Severe infections/pneumonia: 630 mg twice daily (45 mg/kg/dose = 90 mg/kg/day total) 3, 4
- Group A Strep: 700-1,050 mg twice daily (25-37.5 mg/kg/dose = 50-75 mg/kg/day total) 3, 4
Practical Prescribing Details
If Three-Times-Daily Dosing Must Be Used:
- Mild infections: 200 mg per dose every 8 hours (using 250 mg/5 mL suspension = 4 mL per dose) 1
- Severe infections: 375 mg per dose every 8 hours (using 250 mg/5 mL suspension = 7.5 mL per dose) 1
- Duration: 10 days for strep throat (mandatory to prevent rheumatic fever), 7-10 days for respiratory infections 2, 3, 4
Administration Guidelines:
- Give at the start of meals to minimize gastrointestinal side effects 1
- Shake suspension well before each dose 1
- Refrigeration preferred but not required; discard after 14 days 1
Treatment Duration and Monitoring
- Streptococcal infections require 10 days to prevent rheumatic fever 2, 4
- Respiratory infections typically require 7-10 days, with pneumonia specifically needing 10 days 3, 4
- Clinical improvement should occur within 48-72 hours; if not, reassess diagnosis and consider alternative antibiotics 3, 4
- Complete the full course even if symptoms improve 3, 4
Common Pitfalls to Avoid
- Don't underdose larger children: This 28 kg child is just above the 27 kg threshold where some clinicians inappropriately cap doses at "adult maximums" 5
- Don't use three-times-daily for strep throat: The IDSA guidelines clearly recommend twice-daily dosing for better adherence 2, 3
- Don't use amoxicillin alone for suspected MRSA: If skin infection with purulence or systemic toxicity, consider alternative antibiotics 4
- Don't forget the 10-day rule for strep: Shorter courses increase rheumatic fever risk 2, 4