Preparation and Administration of Oral Rehydration Solutions

Standard WHO-ORS Composition and Preparation

The World Health Organization recommends preparing standard oral rehydration solution by mixing per liter of clean water: 3.5 g NaCl, 2.5 g NaHCO₃ or 2.9 g sodium citrate, 1.5 g KCl, and 20 g glucose, to produce approximately Na 90 mM, K 20 mM, Cl 80 mM, HCO₃ 30 mM, and glucose 111 mM 1, 2
For 2 liters, double all quantities above, to maintain the correct electrolyte composition and glucose concentration 1, 2

For mild dehydration (3-5% fluid deficit), administer 50 mL/kg over 2-4 hours, starting with small volumes and gradually increasing as tolerated, according to the Centers for Disease Control and Prevention guidelines 3
For moderate dehydration (6-9% fluid deficit), administer 100 mL/kg over 2-4 hours, to replace lost fluids and electrolytes 3
For ongoing losses, replace with 10 mL/kg for each watery stool and 2 mL/kg for each vomiting episode, to maintain fluid balance 3

The American Gastroenterological Association warns against using plain water, tea, or sugar water alone for rehydration, as hypotonic fluids worsen fluid losses in patients with high-output diarrhea or jejunostomy 4
Severe dehydration (≥10% fluid deficit) requires immediate IV rehydration with Ringer's lactate or normal saline at 20 mL/kg boluses until perfusion normalizes, as recommended by the Centers for Disease Control and Prevention 3

Use clean water, boiled and cooled, or from a safe source, and measure ingredients accurately to avoid incorrect mixing and hypertonic solutions 1, 2, 5
Mix thoroughly until all ingredients dissolve, and prepare fresh daily, discarding unused solution after 24 hours 1, 2
Store in a clean, covered container to maintain solution quality and safety 1, 2