What is the recommended dose of Amoxil (amoxicillin) for an 18kg child with an upper respiratory illness?

Amoxicillin Dosing for an 18kg Child with Upper Respiratory Illness

For an 18kg child with an upper respiratory illness, the recommended dose of amoxicillin is 45 mg/kg/day in 2 divided doses (standard dose) or 90 mg/kg/day in 2 divided doses (high dose) depending on risk factors for resistant organisms. 1, 2

Dosing Recommendations

Standard Dose (First-Line for Uncomplicated Cases)

• 45 mg/kg/day in 2 divided doses 2
  • For an 18kg child: 810mg/day or 405mg twice daily
• Appropriate for children ≥2 years with mild-moderate illness without risk factors for resistant organisms 2

High Dose (For Higher Risk Situations)

• 90 mg/kg/day in 2 divided doses 2
  • For an 18kg child: 1620mg/day or 810mg twice daily
• Indicated when there are risk factors for resistant organisms: 2
  • Age <2 years
  • Child care attendance
  • Recent antibiotic use (within previous 4-6 weeks)
  • High local prevalence of resistant S. pneumoniae (>10%)
  • Moderate to severe illness

Treatment Duration

• For most upper respiratory infections: 5-7 days 2
• For streptococcal infections: minimum 10 days to prevent rheumatic fever 1
• Continue treatment for 48-72 hours beyond symptom resolution 1

Clinical Considerations

When to Use Standard vs. High Dose

• Use standard dose (45 mg/kg/day) for: 2

  • Uncomplicated cases in children ≥2 years
  • No recent antibiotic exposure
  • No daycare attendance
  • Mild symptoms

• Use high dose (90 mg/kg/day) for: 2, 3

  • Children <2 years
  • Recent antibiotic use
  • Daycare attendance
  • Areas with high prevalence of resistant S. pneumoniae
  • Moderate to severe illness

Pathogens to Consider

• Common pathogens in upper respiratory infections include: 2
  • Streptococcus pneumoniae (including penicillin-resistant strains)
  • Haemophilus influenzae
  • Moraxella catarrhalis
  • Group A Streptococcus (in pharyngitis/tonsillitis)

Administration Pearls

• Administer at the start of a meal to minimize gastrointestinal intolerance 1
• Shake oral suspension well before using 1
• Store reconstituted suspension in refrigerator (preferred but not required) 1

Special Situations

For Beta-lactamase Producing Organisms

• Consider amoxicillin-clavulanate if beta-lactamase producing H. influenzae or M. catarrhalis is suspected 2
• Amoxicillin-clavulanate dosing: 90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day of clavulanate in 2 divided doses 2

For Suspected Atypical Pathogens

• If Mycoplasma or Chlamydophila is suspected (especially in children >3 years), consider a macrolide 2
• Azithromycin: 10 mg/kg on day 1, followed by 5 mg/kg/day once daily on days 2-5 2

For Patients Unable to Tolerate Oral Medication

• A single 50 mg/kg dose of ceftriaxone (IM or IV) can be used for children who are vomiting or unable to tolerate oral medication 2

Common Pitfalls to Avoid

• Underdosing amoxicillin in areas with high prevalence of resistant S. pneumoniae 4
• Using standard dose in patients with risk factors for resistant organisms 3
• Unnecessarily using broad-spectrum antibiotics for uncomplicated cases 5
• Treating viral upper respiratory infections with antibiotics when bacterial infection is not suspected 5