How should I evaluate and manage nausea in a 3‑year‑old child?

Evaluation and Management of Nausea in a 3-Year-Old

First assess hydration status and rule out surgical emergencies—particularly bilious vomiting (green color), which indicates intestinal obstruction and requires immediate surgical consultation. 1

Immediate Red Flags Requiring Emergency Evaluation

• Bilious (green) vomiting constitutes a surgical emergency until proven otherwise, indicating possible malrotation or obstruction distal to the ampulla of Vater 1
• Bloody vomit or "currant jelly" stools suggest intussusception and require immediate imaging 1
• Projectile vomiting pattern raises concern for pyloric stenosis, though this typically presents earlier (2-8 weeks of age) 1
• Abdominal distension with lethargy or inconsolable crying suggests mechanical obstruction 1

Assess Hydration Status

Use clinical signs to determine dehydration severity, as physical examination is the most reliable method 1:

• Mild dehydration (3-5% deficit): Slightly decreased urine output, normal mental status 1
• Moderate dehydration (6-9% deficit): Sunken fontanelle, dry mucous membranes, decreased skin turgor, prolonged capillary refill >2 seconds 1
• Severe dehydration (≥10% deficit): Severe lethargy, altered consciousness, cool extremities, poor perfusion, rapid deep breathing 1

Management Based on Hydration Status

For Mild to Moderate Dehydration (Most Common Scenario)

Oral rehydration solution (ORS) is first-line therapy and should be given in small, frequent volumes: 5 mL every 1-2 minutes using a spoon or syringe. 2, 1

• Dosing for mild dehydration: 50 mL/kg ORS over 2-4 hours 2, 1
• Dosing for moderate dehydration: 100 mL/kg ORS over 2-4 hours 2, 1
• Use only commercial ORS (e.g., Pedialyte)—sodas, fruit juices, or homemade mixtures are contraindicated 2
• Replace ongoing losses: 10 mL/kg ORS for each vomiting episode 2, 1

Ondansetron Consideration

At age 3, ondansetron is NOT recommended per current guidelines, which specify use only for children ≥4 years. 2, 3 However, if persistent vomiting completely prevents oral intake, ondansetron 0.2 mg/kg oral (maximum 4 mg) may be considered as an exception 1. Note that ondansetron can prolong QT interval in children with cardiac disease 2.

For Severe Dehydration

Immediate IV fluid bolus of 20 mL/kg isotonic crystalloid (Ringer's lactate or normal saline) is required, repeated until pulse, perfusion, and mental status normalize. 2, 1

Post-Rehydration Care

• Resume age-appropriate oral intake immediately—do not delay feeding 2, 1
• Continue full-strength formula or breast milk—do not dilute 1
• Avoid foods high in simple sugars and fats 1
• Re-assess hydration status 2-4 hours after initiating therapy 2

Critical Safety Points

Never use antimotility agents (loperamide) in children <18 years—risk of respiratory depression, serious cardiac events, and death. 2, 3

When to Return Immediately

Instruct parents to seek immediate care for 2, 1:

• Bilious (green) or projectile vomiting
• Bloody vomit or stool
• Severe lethargy or difficulty waking
• Fewer than 3-4 wet diapers in 24 hours
• Inability to keep down any fluids
• High fever
• Worsening of overall condition

Most Likely Diagnosis

Viral gastroenteritis is the most common cause of acute vomiting in this age group, but this diagnosis should only be made after careful consideration of surgical emergencies and other serious causes 4. Simultaneous correction of dehydration often lessens vomiting frequency 1, making aggressive oral rehydration the cornerstone of management.