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

Amoxicillin Dosing for Pediatric Patients

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 Weighing Less Than 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 3
• The twice-daily regimen improves adherence and is preferred over three-times-daily dosing 1

Severe Infections or High Resistance Areas:

• 45 mg/kg/day divided every 12 hours OR 40 mg/kg/day divided every 8 hours 3
• For community-acquired pneumonia specifically, 90 mg/kg/day in 2 doses is recommended by the Infectious Diseases Society of America 4

Children Weighing 40 kg or More

Mild to Moderate Infections:

• 500 mg every 12 hours OR 250 mg every 8 hours 1, 3

Severe Infections:

• 875 mg every 12 hours OR 500 mg every 8 hours 1, 3

Age-Specific Considerations

Infants Less Than 3 Months (12 Weeks)

Due to incompletely developed renal function, the maximum recommended dose is 30 mg/kg/day divided every 12 hours. 3

• This lower dosing is critical to prevent drug accumulation in neonates 3
• Treatment should continue for at least 48-72 hours beyond symptom resolution 3

Children 3 Months and Older

• Standard weight-based dosing applies as outlined above 1, 3
• For pneumonia, the American Academy of Pediatrics recommends 90 mg/kg/day in 2 doses for children under 5 years 4

Indication-Specific Dosing

Community-Acquired Pneumonia

The preferred regimen is 90 mg/kg/day divided every 12 hours (maximum 4 g/day) for all children with presumed bacterial pneumonia. 4

• This high-dose regimen provides adequate coverage against penicillin-resistant Streptococcus pneumoniae 4
• Treatment duration should be 10 days 2, 4
• Clinical improvement should occur within 48-72 hours; if not, reassess the diagnosis and consider alternative antibiotics 1, 2

Group A Streptococcal Infections (Including Scarlet Fever)

Dose: 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 1, 3
• Patients become non-contagious after 24 hours of therapy 1
• Amoxicillin offers better taste and adherence compared to penicillin V due to twice-daily dosing 2

Otitis Media and Sinusitis

• For mild to moderate infections: 45 mg/kg/day divided every 12 hours 1
• For severe infections or recent antibiotic exposure: 90 mg/kg/day divided every 12 hours 1

Treatment Duration

Most respiratory infections require 7-10 days of treatment, with pneumonia specifically requiring 10 days. 1, 2

• Recent evidence suggests 5-day courses may be as effective as 10-day courses for uncomplicated pneumonia, though 10 days remains the standard recommendation 5
• Group A Streptococcal infections must be treated for 10 days to prevent rheumatic fever 1, 3
• Continue treatment for at least 48-72 hours beyond symptom resolution 3

Renal Impairment Adjustments

For children weighing >40 kg with renal impairment:

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

Critical Administration Details

Every prescription must include:

• Total daily dose in mg/kg/day 1
• Number of divided doses per day 1
• Duration of therapy 1
• Indication for prescription 1
• Child's weight 6

Administration tips:

• Give at the start of a meal to minimize gastrointestinal intolerance 3
• Oral suspension can be mixed with formula, milk, fruit juice, water, or cold drinks and taken immediately 3
• Shake suspension well before each use 3
• Refrigeration is preferable but not required; discard unused suspension after 14 days 3

Common Pitfalls and Caveats

Inadequate Dosing for Resistant Organisms

The traditional 40 mg/kg/day dosing is inadequate for resistant Streptococcus pneumoniae, particularly during viral coinfection. 7

• Middle ear fluid penetration studies show lower amoxicillin concentrations in children with viral coinfection 7
• High-dose therapy (75-90 mg/kg/day) is necessary for adequate bacterial eradication in areas with resistance 7

MRSA Considerations

Amoxicillin has NO activity against MRSA; if suspected or confirmed, alternative antibiotics must be used. 1

• For community-associated MRSA pneumonia, add clindamycin (30-40 mg/kg/day in 3-4 doses) 4
• For confirmed MRSA, use vancomycin (40-60 mg/kg/day every 6-8 hours) or linezolid 4

β-lactamase Producing Organisms

For β-lactamase producing Haemophilus influenzae, amoxicillin alone is insufficient; use amoxicillin-clavulanate instead. 2, 4

• Dose: 45 mg/kg/day in 3 doses OR 90 mg/kg/day in 2 doses (of amoxicillin component) 2, 4

Monitoring and Follow-Up

Clinical improvement should occur within 48-72 hours of starting appropriate therapy. 1, 2

• If no improvement by 72 hours, reassess the diagnosis and consider alternative pathogens or antibiotic resistance 1, 2
• Complete the full prescribed course even if symptoms improve before completion 1, 2

Adverse Effects

The most common adverse effects are gastrointestinal disturbances including diarrhea, nausea, and vomiting. 1, 2

• Rash, urticaria, and hypersensitivity reactions may occur 1, 2
• For non-serious allergic reactions, consider oral cephalosporins (cefpodoxime, cefprozil, or cefuroxime) under medical supervision 4
• For severe reactions, consider macrolides, though resistance rates may be higher 4