A 2-year-old with vomiting, diarrhea, and poor oral intake. What is the recommended rehydration strategy?

• A. IV fluids are always preferred for dehydration.
• B. Oral rehydration solution (ORS) with 50 mL/kg over 4 hours for mild-moderate dehydration; IV fluids for severe dehydration.
• C. Only water and electrolyte-free beverages.
• D. No treatment is needed.

Answer: (B)

When a young child has dehydration from diarrhea and vomiting, rehydration with oral electrolyte solution is preferred if the dehydration is not severe. The reason is that oral rehydration uses the sodium-glucose transporter in the small intestine to maximize water absorption, which is effective, safe, and avoids the need for IV access in many cases.

The recommended plan for mild to moderate dehydration is to give about 50 mL of oral rehydration solution per kilogram of body weight over about 4 hours, while continuing to offer fluids and age-appropriate foods in between. For example, a 12‑kg toddler would receive roughly 600 mL over 4 hours. If vomiting makes it hard to take larger volumes at once, provide small, frequent sips and resume regular feeds as tolerated. If the child cannot keep ORS down or if there are signs of severe dehydration (such as very fast heart rate, lethargy, poor skin turgor, or reduced eye fullness), switch to IV isotonic fluids and reassess promptly.

Choosing to rely on plain water or electrolyte-free beverages won’t replace losses adequately and can risk hyponatremia or persistent dehydration. IV fluids are appropriate only when dehydration is severe or oral intake cannot be maintained.