What is the maximum recommended dose of amoxicillin for a pediatric patient?

Maximum Dose of Amoxicillin for Pediatric Patients

The maximum recommended dose of amoxicillin for pediatric patients is 90 mg/kg/day divided into 2 doses (45 mg/kg/dose twice daily), not to exceed the adult maximum dose of 1500 mg/day for most indications. 1

Dosing by Age and Indication

Children ≥3 Months and <40 kg

For severe infections or resistant pathogens:

• 90 mg/kg/day divided every 12 hours (45 mg/kg/dose twice daily)
• Alternative: 40 mg/kg/day divided every 8 hours
• This applies to severe ear/nose/throat infections, lower respiratory tract infections, and pneumococcal infections with intermediate penicillin resistance 2, 3, 2, 3, 2, 1

For mild to moderate infections:

• 25 mg/kg/day divided every 12 hours or 20 mg/kg/day divided every 8 hours 1

For β-lactamase negative H. influenzae:

• 75-100 mg/kg/day in 3 divided doses 2, 3, 2

Children <3 Months (Neonates)

Maximum dose: 30 mg/kg/day divided every 12 hours due to immature renal function 1

Children ≥40 kg and Adolescents

Use adult dosing:

• Severe infections: 875 mg every 12 hours or 500 mg every 8 hours
• Maximum daily dose: 1500 mg/day 1

Critical Dosing Considerations

The "Adult Maximum" Problem

A significant clinical pitfall exists: Children weighing >15-20 kg frequently receive subtherapeutic doses because clinicians cap the dose at the adult maximum of 1500 mg/day 4, 5. This creates a dosing disparity where:

• Small children (<6 years) typically receive appropriate doses around 80-90 mg/kg/day
• Larger children (>60 kg) often receive <40 mg/kg/day, which is inadequate for resistant organisms 5

The correct approach: Calculate the weight-based dose (up to 90 mg/kg/day) and prescribe it even if it exceeds 1500 mg/day in heavier children, particularly for severe infections or resistant pathogens. The FDA label supports doses up to 90 mg/kg/day without specifying an absolute maximum 1.

Specific Clinical Scenarios

For acute otitis media with high-risk features:

• Use 80-90 mg/kg/day when the child has received antibiotics in the past 30 days, has concurrent conjunctivitis, attends daycare, or when local pneumococcal resistance is high 6
• Standard dose (40-45 mg/kg/day) may be adequate in communities with low resistance rates 7

For community-acquired pneumonia:

• High-dose (80-90 mg/kg/day) is preferred for hospitalized children or those with severe disease 2, 3, 2
• Recent evidence suggests lower doses (35-50 mg/kg/day) may be noninferior for less severe CAP, but this remains controversial 8

For Group A Streptococcus pharyngitis:

• 50-75 mg/kg/day in 2 divided doses 2, 3, 2, 3, 2

Renal Impairment

For children with severe renal impairment (GFR <30 mL/min):

• Maximum 500 mg every 12-24 hours depending on severity
• Do NOT use the 875 mg dose formulation 1

Key Clinical Pearls

• Always dose by weight (mg/kg/day), not by age, up to the calculated maximum
• Viral coinfection reduces amoxicillin efficacy, potentially requiring higher doses 9
• Middle ear fluid concentrations peak 3 hours after dosing and are lower with viral coinfection 9
• Obesity does not change the mg/kg dosing recommendation—use actual body weight 4
• Duration matters less than dose: 3-day courses may be noninferior to 7-day courses for some indications, but adequate dosing is critical 8