Amoxicillin Pediatric Dosing Guidelines
For most pediatric respiratory infections, amoxicillin should be dosed at 45 mg/kg/day divided every 12 hours for mild-to-moderate infections, or 90 mg/kg/day divided every 12 hours for severe infections or areas with high pneumococcal resistance, with a maximum daily dose of 4000 mg. 1, 2
Standard Dosing by Weight and Severity
Children ≥3 Months and <40 kg
Mild to Moderate Infections (Ear/Nose/Throat, Skin, Genitourinary):
- 25 mg/kg/day divided every 12 hours OR 20 mg/kg/day divided every 8 hours 2, 3
- The twice-daily regimen improves adherence and is preferred over three-times-daily dosing 2
Severe Infections or High Pneumococcal Resistance:
Lower Respiratory Tract Infections (All Severities):
- 45 mg/kg/day divided every 12 hours OR 40 mg/kg/day divided every 8 hours 1, 2, 3
- This higher dose is recommended for all lower respiratory tract infections regardless of severity 1
Children ≥40 kg and Adolescents
Mild to Moderate Infections:
Severe Infections:
Infants <3 Months (12 Weeks)
- Maximum 30 mg/kg/day divided every 12 hours due to immature renal function 1, 3
- No dosing recommendations exist for infants with renal impairment in this age group 3
Indication-Specific Dosing
Group A Streptococcal Pharyngitis (Including Scarlet Fever)
- 50-75 mg/kg/day divided into 2 doses for 10 days, not exceeding 1000 mg per dose 1, 2
- The 10-day duration is mandatory to prevent rheumatic fever 2
- Patients become non-contagious after 24 hours of therapy 2
- Amoxicillin offers better taste and adherence compared to penicillin V due to twice-daily dosing 1
Community-Acquired Pneumonia
- 45 mg/kg/day in 2 doses for mild-to-moderate cases 1
- 90 mg/kg/day in 2 doses for severe cases or high pneumococcal resistance (>10% prevalence) 1, 2
- Treatment duration: 10 days 1, 2
Critical Administration Details
Every prescription must include: 2
- Total daily dose in mg/kg/day
- Number of divided doses per day
- Duration of therapy
- Indication for prescription
- Child's weight
Administration timing:
- Give at the start of meals to minimize gastrointestinal intolerance 3
Treatment Duration
- Respiratory infections: 7-10 days, with pneumonia specifically requiring 10 days 1, 2
- Group A Streptococcal infections: Mandatory 10 days to prevent rheumatic fever 2
- Continue treatment for minimum 48-72 hours beyond symptom resolution or bacterial eradication 2, 3
Monitoring and Follow-Up
- Clinical improvement should occur within 48-72 hours of starting treatment 1, 2
- If no improvement by 72 hours, reassess diagnosis and consider alternative antibiotics 2
- Complete the full prescribed course even if symptoms improve 1, 2
Renal Impairment Adjustments (≥3 Months and >40 kg)
- GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours (depending on severity) 2, 3
- GFR <10 mL/min: 500 mg or 250 mg every 24 hours 2, 3
- Hemodialysis: 500 mg or 250 mg every 24 hours, with additional dose during and at end of dialysis 3
- Do NOT use 875 mg dose in patients with GFR <30 mL/min 3
Common Adverse Effects
- Gastrointestinal disturbances (diarrhea, nausea, vomiting) are most common 1, 2
- Rash, urticaria, and hypersensitivity reactions may occur 1, 2
- Monitor patients throughout treatment for these effects 2
Critical Pitfalls to Avoid
Underdosing consequences:
- The traditional 40 mg/kg/day dosing is inadequate for resistant Streptococcus pneumoniae, particularly with viral coinfection 4
- Subtherapeutic doses fail to achieve adequate tissue concentrations and promote antimicrobial resistance 1
- Treatment failure with resistant organisms is inevitable when standard doses are not used 1
MRSA consideration:
- If MRSA is suspected or confirmed, amoxicillin alone will not be effective and alternative antibiotics must be considered 2
Viral infections:
- Most upper respiratory tract infections are viral and do not benefit from antibiotics 1
- Ensure bacterial infection criteria are met before prescribing 1