What is the recommended dosage of amoxicillin (amoxicillin) for pediatric patients?

Amoxicillin Dosing for Pediatric Patients

For pediatric patients, amoxicillin dosing is weight-based and indication-specific: use 45 mg/kg/day divided every 12 hours for mild-to-moderate respiratory infections, and 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 Infection Severity

Mild to Moderate Infections

• For children weighing less than 40 kg, the recommended dose is 25 mg/kg/day divided every 12 hours (or 20 mg/kg/day divided every 8 hours) for ear/nose/throat, skin/skin structure, and genitourinary tract infections 3
• For children weighing 40 kg or more, administer 500 mg every 12 hours or 250 mg every 8 hours 3
• The American Academy of Pediatrics specifically recommends 45 mg/kg/day divided every 12 hours for mild-to-moderate respiratory infections, which provides adequate coverage while minimizing adverse effects 1, 2

Severe Infections or High Resistance Areas

• For children weighing less than 40 kg, use 45 mg/kg/day divided every 12 hours (or 40 mg/kg/day divided every 8 hours) for severe infections 3
• For lower respiratory tract infections (regardless of severity), the dose is 45 mg/kg/day divided every 12 hours or 40 mg/kg/day divided every 8 hours 3
• In areas with high pneumococcal resistance or for severe pneumonia, increase to 90 mg/kg/day divided every 12 hours 1, 2

Specific Indications

Group A Streptococcal Infections (Including Scarlet Fever and Impetigo)

• Administer 50-75 mg/kg/day divided into 2 doses for 10 days, not exceeding 1000 mg per dose 1, 2, 4
• The 10-day duration is mandatory to prevent rheumatic fever, regardless of symptom resolution 1, 3
• Patients become non-contagious after 24 hours of therapy 1, 4

Respiratory Tract Infections

• Treatment duration should be 7-10 days for most respiratory infections, with pneumonia specifically requiring 10 days 1, 2
• Recent high-quality evidence from the CAP-IT trial suggests that 3-day courses may be non-inferior to 7-day courses for uncomplicated community-acquired pneumonia, though time to cough resolution was slightly longer with shorter courses 5
• However, current guidelines still recommend the longer duration, and 10 days remains the standard of care 1, 2

Age-Specific Considerations

Infants Less Than 12 Weeks (3 Months)

• Maximum dose is 30 mg/kg/day divided every 12 hours due to incompletely developed renal function 3
• Treatment should continue for at least 48-72 hours beyond symptom resolution 3
• For Streptococcus pyogenes infections, maintain at least 10 days of treatment 3

Children 3 Months and Older

• Dosing follows the weight-based recommendations outlined above 1, 3
• Twice-daily dosing improves adherence compared to three-times-daily regimens, making the every-12-hour schedule preferred 1

Renal Impairment Adjustments

• Patients with GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours, depending on infection severity 1, 3
• Patients with GFR less than 10 mL/min: 500 mg or 250 mg every 24 hours 1, 3
• Hemodialysis patients: 500 mg or 250 mg every 24 hours, with an additional dose during and at the end of dialysis 3
• Patients with GFR less than 30 mL/min should NOT receive the 875 mg dose 3

Critical Administration Details

Prescription Requirements

• Every prescription must include: total daily dose in mg/kg/day, number of divided doses per day, duration of therapy, indication for prescription, and the child's weight 1, 2
• Amoxicillin should be taken at the start of a meal to minimize gastrointestinal intolerance 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 the diagnosis and consider alternative antibiotics 1, 2
• Complete the full prescribed course even if symptoms improve 1, 2

Common Adverse Effects and Pitfalls

Expected Side Effects

• Gastrointestinal disturbances (diarrhea, nausea, vomiting) are most common 1, 2
• Rash, urticaria, and hypersensitivity reactions may occur 1, 2

Critical Pitfalls to Avoid

• If MRSA is suspected or confirmed, amoxicillin alone will not be effective and alternative antibiotics must be considered 1, 4
• The older WHO recommendation of 15 mg/kg/dose three times daily is inadequate for resistant Streptococcus pneumoniae, particularly during viral coinfection 6
• Research demonstrates that 40 mg/kg/day dosing is insufficient to eradicate resistant pneumococci, supporting the current recommendation of 75-90 mg/kg/day for resistant organisms 6
• Age-based dosing is less accurate than weight-based dosing and should be avoided 7