What is the recommended dosage of amoxicillin (amoxicillin) for children?

Amoxicillin Dosing for Children

For most pediatric infections, amoxicillin should be dosed at 45 mg/kg/day divided every 12 hours for mild to moderate 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

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 2
• For common uncomplicated infections, 60 mg/kg/day in two divided doses is also recommended 3

Severe Infections or Lower Respiratory Tract:

• 45 mg/kg/day divided every 12 hours OR 40 mg/kg/day divided every 8 hours 2
• For pneumonia specifically, 90 mg/kg/day in 2 doses is the definitive first-line treatment 1, 4

Children Weighing 40 kg or More

Mild to Moderate Infections:

• 500 mg every 12 hours OR 250 mg every 8 hours 2

Severe Infections:

• 875 mg every 12 hours OR 500 mg every 8 hours 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 2
• No dosing recommendations exist for infants with impaired renal function in this age group 2

Children 3 Months and Older

• Standard weight-based dosing applies as outlined above 1, 2
• The higher dose of 90 mg/kg/day is essential to overcome pneumococcal resistance, and underdosing with 40-45 mg/kg/day is a common and dangerous error 4

Indication-Specific Dosing

Group A Streptococcal Infections (Strep Throat)

• 50-75 mg/kg/day divided into 2 doses for 10 days, not exceeding 1000 mg per dose 1
• Must treat for 10 days to prevent rheumatic fever 1, 2
• Patients become non-contagious after 24 hours of therapy 1

Community-Acquired Pneumonia

• 90 mg/kg/day in 2 doses (maximum 4 g/day) for both children under 5 years and those 5 years and older 4, 5
• This higher dose is necessary because the current 40 mg/kg/day recommendation is inadequate to eradicate resistant Streptococcus pneumoniae 6
• Treatment duration is 10 days 1

Acute Otitis Media

• A dosing regimen of 75-90 mg/kg/day is recommended, as the standard 40 mg/kg/day in three divided doses is inadequate to effectively eradicate resistant Streptococcus pneumoniae, particularly during viral coinfection 6

Renal Impairment Adjustments

GFR 10-30 mL/min:

• 500 mg or 250 mg every 12 hours, depending on severity 2

GFR Less Than 10 mL/min:

• 500 mg or 250 mg every 24 hours 2

Hemodialysis:

• 500 mg or 250 mg every 24 hours, with an additional dose both during and at the end of dialysis 2

Important: Patients with GFR less than 30 mL/min should NOT receive the 875 mg dose 2

Critical Prescribing Details

Every prescription must include: 1, 3

• Total daily dose in mg/kg/day
• Number of divided doses per day
• Duration of therapy
• Indication for prescription
• Child's weight 3

Administration:

• Should be taken at the start of a meal to minimize gastrointestinal intolerance 2
• Twice-daily dosing improves adherence compared to three-times-daily regimens, making 45-90 mg/kg/day divided every 12 hours the preferred approach 1

Treatment Duration and Monitoring

Standard Duration:

• Continue for a minimum of 48-72 hours beyond when the patient becomes asymptomatic 2
• For Streptococcus pyogenes infections, at least 10 days of treatment is mandatory to prevent acute rheumatic fever 2
• For pneumonia, 10 days is required 1

Clinical Monitoring:

• Clinical improvement should occur within 48-72 hours of starting treatment 1, 4
• If no improvement by 72 hours, reassess the diagnosis and consider alternative antibiotics 1
• Complete the full prescribed course even if symptoms improve 1

Common Pitfalls to Avoid

Underdosing: Using 40-45 mg/kg/day instead of the recommended 90 mg/kg/day for pneumonia or resistant infections is a dangerous error that leads to treatment failure 4, 6

Inadequate Duration: Stopping treatment early for streptococcal infections risks rheumatic fever 1, 2

MRSA Consideration: If MRSA is suspected or confirmed, amoxicillin alone will not be effective and alternative antibiotics must be considered 1

Viral Coinfection: Amoxicillin penetration into middle ear fluid tends to be lower in children with viral infection, potentially requiring higher doses 6

Adverse Effects

Most Common:

• Gastrointestinal disturbances (diarrhea, nausea, vomiting) 1
• Rash, urticaria, and hypersensitivity reactions 1

Serious (Rare):

• Anaphylaxis, Stevens-Johnson syndrome, toxic epidermal necrolysis 7, 2
• Seizures (especially in patients with renal impairment or those taking medications that lower seizure threshold) 7

Oral Suspension Preparation

After reconstitution:

• Shake well before each use 2
• Keep bottle tightly closed 2
• Refrigeration is preferable but not required 2
• Discard any unused portion after 14 days 2