What is the appropriate amoxicillin dose for a 5-year-old child weighing 23 kg using a suspension of 400 mg per 5 mL?

Amoxicillin Dosing for a 5-Year-Old Child Weighing 23 kg

For most common infections (otitis media, pharyngitis, sinusitis), give 575 mg (approximately 7.2 mL of the 400 mg/5 mL suspension) every 12 hours, which provides the standard dose of 50 mg/kg/day. 1

Standard Dosing Algorithm

For Mild to Moderate Infections

• The FDA recommends 25 mg/kg/day divided every 12 hours (or 20 mg/kg/day divided every 8 hours) for mild to moderate ear/nose/throat, skin, and genitourinary infections in children weighing less than 40 kg 1
• For this 23 kg child, the mild/moderate dose would be 287.5 mg every 12 hours (approximately 3.6 mL of your suspension) 1

For Severe Infections or Resistant Organisms

• The FDA recommends 45 mg/kg/day divided every 12 hours (or 40 mg/kg/day divided every 8 hours) for severe infections 1
• For this 23 kg child, the high-dose regimen would be 517.5 mg every 12 hours (approximately 6.5 mL of your suspension) 1

For High-Dose Therapy (Resistant Streptococcus pneumoniae)

• The American Academy of Pediatrics and Infectious Diseases Society of America recommend 90 mg/kg/day divided into 2 doses for community-acquired pneumonia or when resistant pathogens are suspected 2
• For this 23 kg child, this translates to 1,035 mg every 12 hours (approximately 12.9 mL of your suspension) 2
• This high-dose regimen is specifically designed to overcome penicillin-resistant Streptococcus pneumoniae 2

Practical Dosing Recommendations by Indication

Acute Otitis Media (Standard)

• Give 575 mg (7.2 mL) every 12 hours for 5-7 days 1, 2
• This provides approximately 50 mg/kg/day, which is appropriate for most cases 1

Acute Otitis Media (Recurrent or Treatment Failure)

• Consider high-dose amoxicillin at 1,035 mg (12.9 mL) every 12 hours 2
• If this fails, switch to amoxicillin-clavulanate 90 mg/kg/day (amoxicillin component) 2, 3

Community-Acquired Pneumonia

• Use high-dose therapy: 1,035 mg (12.9 mL) every 12 hours for 5-7 days 2
• The Infectious Diseases Society of America specifically recommends 90 mg/kg/day divided into 2 doses for pneumonia 2

Streptococcal Pharyngitis

• Standard dose: 575 mg (7.2 mL) every 12 hours for at least 10 days 1, 2
• The FDA mandates at least 10 days of treatment for Streptococcus pyogenes to prevent acute rheumatic fever 1

Administration Guidelines

• Give amoxicillin at the start of a meal to minimize gastrointestinal intolerance 1
• Shake the suspension well before each use 1
• Store the reconstituted suspension in the refrigerator (preferred but not required) and discard after 14 days 1

Critical Dosing Considerations

Maximum Daily Dose

• The absolute maximum amoxicillin dose is 4,000 mg/day, regardless of weight 3
• For this 23 kg child, even the highest recommended dose (90 mg/kg/day = 2,070 mg/day) is well below this maximum 2, 3

Duration of Therapy

• Continue treatment for a minimum of 48-72 hours beyond symptom resolution or evidence of bacterial eradication 1
• For Streptococcus pyogenes infections, always treat for at least 10 days to prevent rheumatic fever 1

When to Use High-Dose Therapy

• Recent antibiotic use within the past 30 days 2
• Daycare attendance 2
• Age less than 2 years 2
• Geographic areas with high rates of penicillin-resistant S. pneumoniae 2, 4
• Treatment failure with standard-dose amoxicillin 2, 5

Common Pitfalls to Avoid

• Do not underdose for severe infections: Research demonstrates that 40 mg/kg/day is inadequate for resistant S. pneumoniae, particularly during viral coinfection 6
• Do not use the 875 mg tablet formulation in children with renal impairment (GFR <30 mL/min), though this is unlikely relevant for a healthy 5-year-old 1
• Do not stop treatment early: Even if the child improves rapidly, complete the full course, especially for streptococcal infections 1