ORS Aim of oral rehydration therapy is to prevent dehydration and reduce moality. Oral fluid therapy is based on the observation that glucose given orally enhances the intestinal absorption of salt and water and is capable of correcting electrolyte and water deficit. At first the composition of oral rehydration salt recommended by WHO was sodium bicarbonate based. Inclusion of trisodium citrate in place of sodium bicarbonate made the product more stable and it resulted in less stool output especially in high output diarrhoea, probably because of direct effect of trisodium citrate in increasing intestinal absorption of sodium and water. More recently an improved ORS formulation has been developed which is safe and effective as the original in preventing and treating diarrhoeal dehydration. It is focussed on reducing the osmolarity of ORS solution to avoid adverse effects of hypeonicity on net fluid absorption by reducing the concentration of glucose and sodium chloride in the solution. A freshly prepared ORS should be used before 24hrs. Decreasing the sodium concentration of ORS solution to 75 mOsm/l improved the efficacy of ORS regimen for children with acute non cholera diarrhoea. Reduced osmolarity ORS:-(g/L) Sodium chloride- 2.6 Glucose,anhydrous- 13.5 Potassium chloride- 1.5 Trisodium citrate,dihydrate-2.9 Total =20.5 g/L Reduced osmolarity ORS:-(mmol/L) Sodium-75 Chloride-65 Glucose,anhydrous-75 Potassium-20 Citrate-10 Total = 245 mmol/L Guidelines for oral rehydration therapy in first four hours(as per weight) 1. Under 5 kg:200-400 ml 2. 5-7.9 kg: 400-600 ml 3. 8-10.9 kg : 600-800 ml 4. 11-15.9 kg: 800-1200 ml 5. 16-29.9 kg: 1200-2200 ml 6. 30/ above: 2200-4000 ml {Reference: park&;s textbook of preventive and social medicine, 23rd edition, pg no.224}