What is the best course of treatment for an infant experiencing vomiting and diarrhea?

Treatment of Infant Vomiting and Diarrhea

Oral rehydration solution (ORS) is the first-line treatment for infants with vomiting and diarrhea, regardless of severity, unless severe dehydration with shock is present. 1

Immediate Assessment

Evaluate dehydration severity by examining:

• Skin turgor, mucous membranes, mental status, pulse, and capillary refill time 2
• Weight loss (the most reliable indicator of fluid deficit) 2
• Urine output and thirst (early signs of dehydration) 3

Categorize dehydration as:

• Mild (3-5% fluid deficit) 2
• Moderate (6-9% fluid deficit) 2
• Severe (≥10% fluid deficit, shock, or altered mental status) 2

Rehydration Protocol

For Mild to Moderate Dehydration

Administer reduced osmolarity ORS (containing 50-90 mEq/L sodium) as follows: 1

• Mild dehydration: 50 mL/kg ORS over 2-4 hours 2
• Moderate dehydration: 100 mL/kg ORS over 2-4 hours 2

Managing Vomiting During Rehydration

Give small, frequent volumes (5 mL every 1-2 minutes) using a spoon or syringe 1, 2. This gradual approach is critical—allowing a thirsty infant to drink large volumes worsens vomiting. 2 Simultaneous correction of dehydration typically reduces vomiting frequency. 1

If oral intake fails despite small-volume technique, consider nasogastric ORS administration 1, which has been shown to be as effective as IV rehydration with shorter hospitalization and lower costs. 4

For Severe Dehydration

Administer intravenous isotonic crystalloid (lactated Ringer's or normal saline) in 20 mL/kg boluses until pulse, perfusion, and mental status normalize 1, 2, then transition to ORS to complete rehydration. 2

Ongoing Fluid Replacement

After initial rehydration, replace ongoing losses with: 1, 2

• 10 mL/kg ORS for each watery stool 2
• 2 mL/kg ORS for each vomiting episode 2

Continue this replacement until diarrhea and vomiting resolve. 1

Feeding During Illness

Breastfed Infants

Continue breastfeeding on demand throughout the entire illness without interruption 1, 2. Breast milk reduces stool output and severity of diarrhea. 5, 3

Formula-Fed Infants

Resume full-strength formula immediately upon rehydration 1, 2. Use lactose-free or lactose-reduced formula if available, but full-strength lactose-containing formula is acceptable under supervision. 1 Do not dilute formula—this worsens nutritional outcomes and prolongs diarrhea. 5

True lactose intolerance is diagnosed only by worsening diarrhea with lactose reintroduction, not by stool pH or reducing substances alone 1, 5

Older Infants on Solid Foods

Resume age-appropriate diet during or immediately after rehydration 1, 2. Recommended foods include starches, cereals, yogurt, fruits, and vegetables; avoid foods high in simple sugars and fats. 1, 2

Medications: Critical Contraindications and Limited Indications

Absolutely Contraindicated

Antimotility drugs (loperamide) are absolutely contraindicated in all children under 18 years of age 1, 2 due to risks of respiratory depression, cardiac arrest, and death. 6 The FDA specifically warns against use in children under 2 years due to serious cardiac adverse reactions and respiratory depression. 6

May Consider After Adequate Hydration

Ondansetron may be given to children >4 years of age to facilitate oral rehydration when vomiting is present, but only after adequate hydration is achieved 1, 2. This increases oral rehydration success and reduces need for IV therapy. 2

Antibiotics

Antibiotics are not routinely indicated 1, 2 unless:

• Dysentery (bloody diarrhea) is present 2
• High fever occurs 2
• Watery diarrhea persists >5 days 2
• Stool cultures indicate a treatable pathogen 2

Adjunctive Therapies

Probiotics may be offered to reduce symptom severity and duration 1, 2, though specific organism selection should be guided by literature and manufacturer guidance. 1

Zinc supplementation (for children 6 months to 5 years) reduces diarrhea duration in areas with high zinc deficiency prevalence or in malnourished children 1, 2

Warning Signs Requiring Immediate Medical Attention

Return immediately or seek emergency care if the infant develops: 1, 2, 5

• Lethargy or irritability 2
• Decreased urine output 1, 2
• Intractable vomiting preventing oral rehydration 2
• Signs of severe dehydration (sunken eyes, very poor skin turgor, altered mental status) 5
• High stool output (>10 mL/kg/hour) 2
• Bloody diarrhea 2

Common Pitfalls to Avoid

• Do not allow thirsty infants to drink large volumes rapidly—this worsens vomiting 2
• Do not use inappropriate beverages (cola drinks, apple juice, Gatorade, commercial soft drinks) for rehydration—these contain inadequate sodium and excessive osmolarity that may worsen diarrhea 1, 3
• Do not delay full-strength feeding after rehydration—early feeding shortens diarrhea duration 1, 3
• Do not use antidiarrheal medications in infants—they do not prevent dehydration and carry life-threatening risks 6, 3