Management of Acute Diarrhea in Infants

Hydration Assessment and Rehydration Strategy

The American Academy of Pediatrics recommends immediately assessing hydration status and beginning oral rehydration solution (ORS) while continuing breast milk or formula feeding without interruption in infants with acute diarrhea 1
For mild dehydration (3-5% fluid deficit), administer 50 mL/kg of ORS over 2-4 hours, and replace ongoing losses with 10 mL/kg ORS for each watery stool and 2 mL/kg for each vomiting episode 1, 2
For moderate dehydration (6-9% fluid deficit), administer 100 mL/kg of ORS over 2-4 hours, and use the same replacement strategy for ongoing losses as above 1
For severe dehydration (≥10% fluid deficit, shock), this is a medical emergency requiring immediate IV rehydration, and administer 20 mL/kg boluses of Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize 2, 4

The American Academy of Pediatrics recommends continuing breast milk or formula feeding immediately, even during rehydration, in infants with acute diarrhea 1, 3
For breast-fed infants, continue nursing on demand throughout the illness, as breast-feeding during diarrhea reduces stool output and severity 1, 3, 5, 6
For formula-fed infants, administer full-strength, lactose-free or lactose-reduced formula immediately upon rehydration, and consider lactose-free protein hydrolysate formula for 2-4 weeks in severe cases 1, 3

Neither antibiotics nor antidiarrheal agents are indicated for routine acute diarrhea in infants, according to the Centers for Disease Control and Prevention 1, 2, 3
Antibiotics should only be used when dysentery (bloody diarrhea) or high fever is present, watery diarrhea persists for >5 days, or stool cultures or clinical setting indicate a specific treatable pathogen (e.g., Shigella) 1, 2, 3

Never use homemade solutions, plain water, cola drinks, undiluted apple juice, or other high-sugar beverages for rehydration, as they are either hyperosmolar (worsening diarrhea) or contain inadequate sodium for rehydration, according to the World Health Organization 5
Only use commercially prepared ORS with appropriate sodium content (60-90 mEq/L) for rehydration 1, 2

Parents should return immediately if the infant develops irritability or lethargy, decreased urine output, intractable vomiting, persistent or worsening diarrhea, or signs of severe dehydration, as recommended by the American Academy of Pediatrics 2, 3