What are the recommended dosages for medications in a child with fever and vomiting?

Recommended Medication Dosages for Children with Fever and Vomiting

For a child with fever and vomiting, acetaminophen (10-15 mg/kg every 4-6 hours) and ondansetron (weight-based dosing) are the recommended medications, with specific dosages determined by the child's weight and age.

Antipyretic Medications

Acetaminophen

• Dosage: 10-15 mg/kg/dose every 4-6 hours 1, 2, 3
• Maximum: Do not exceed 5 doses in 24 hours
• Weight-based dosing:
  • <15 kg: Calculate exact dose at 15 mg/kg
  • 15-23 kg: 240 mg per dose
  • 24-40 kg: 325-400 mg per dose

  • 40 kg: 500-650 mg per dose

Ibuprofen (alternative to acetaminophen)

• Dosage: 5-10 mg/kg/dose every 6-8 hours 2
• Age restriction: Only for children >6 months of age
• Maximum: Do not exceed 40 mg/kg/day

Antiemetic Medications

Ondansetron (first-line for vomiting)

• Dosage based on weight 4, 5, 6:
  • <15 kg: 2 mg every 12 hours
  • 15-23 kg: 4 mg every 12 hours

  • 24 kg: 4-8 mg every 12 hours

• Duration: Continue for 1-2 days as needed
• Evidence: Shown to reduce risk of recurrent vomiting, need for IV fluids, and hospital admissions 5, 6

Promethazine (second-line, use with caution)

• Age restriction: Contraindicated in children under 2 years 7
• Dosage: 0.5 mg/kg/dose every 4-6 hours as needed 7
• Maximum: 25 mg per dose
• Warning: Use with caution due to risk of respiratory depression

Antibiotic Considerations

If bacterial infection is suspected:

For children with suspected complicated intra-abdominal infection

• Age-appropriate antibiotics 8, 9:
  • <5 years: Amoxicillin 90 mg/kg/day divided in 2 doses
  • ≥5 years: Amoxicillin 90 mg/kg/day (max 4 g/day)
  • Alternative: Ceftriaxone for hospitalized patients

Treatment Algorithm

1. Assess severity:

   • Check vital signs (temperature, heart rate, respiratory rate)
   • Evaluate hydration status (skin turgor, mucous membranes, urine output)
   • Assess for signs of serious illness (lethargy, decreased responsiveness)

2. For fever management:

   • If temperature >38°C (>38.5°C in children), administer acetaminophen
   • Goal is comfort rather than normalization of temperature 2
   • Reassess temperature in 1 hour

3. For vomiting management:

   • If ≥2 episodes of vomiting in previous 4 hours, consider ondansetron
   • Wait 30 minutes after ondansetron before attempting oral rehydration
   • Start with small sips (5-15 mL) every 5-10 minutes

4. Reassessment:

   • Evaluate response to antipyretic within 1-2 hours
   • Assess vomiting control within 6 hours 6
   • If no improvement in 24 hours or worsening symptoms, reassess diagnosis

Important Considerations and Pitfalls

• Avoid combination therapy: While combining acetaminophen and ibuprofen may be more effective, it can lead to dosing errors and potential toxicity 2

• Weight-based dosing: Always calculate doses based on accurate weight measurements, not age alone 9

• Hydration focus: Prioritize oral rehydration therapy with small, frequent amounts of clear fluids

• Warning signs: Seek immediate medical attention for:

  • Persistent vomiting despite medication
  • Signs of dehydration (decreased urination, dry mouth, no tears)
  • Lethargy or altered mental status
  • Severe abdominal pain

• Common errors to avoid:

  • Using standard adult doses instead of weight-based dosing 9
  • Not reassessing after 48-72 hours if no clinical improvement 9
  • Administering antipyretics for low-grade fever without discomfort 2
  • Using promethazine in children under 2 years 7

By following these evidence-based dosing recommendations and treatment approach, you can effectively manage fever and vomiting in children while minimizing risks and complications.