Composition of ORS (Oral Rehydration Solution)

WHO/UNICEF Recommended Reduced-Osmolarity ORS (current standard since 2004)

Grams per litre (what goes into the packet):

Millimoles per litre (electrolyte concentrations):

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Key points

• Trisodium citrate replaced sodium bicarbonate in the older formula because it is more stable and results in less stool output, particularly in high-output diarrhea like cholera. Citrate (10 mmol/L) provides an equivalent of 30 mmol/L of HCO3-.
• The reduced osmolarity (245 mOsm/L) replaced the older formulation (311 mOsm/L). The lower glucose and NaCl concentrations reduced stool output by ~20%, vomiting by ~30%, and the need for IV therapy by ~33% in children with non-cholera diarrhea.
• India was the first country to launch this new formulation (June 2004); UNICEF has procured only this formulation since January 2004.
• The Na:Glucose ratio is 1:1, which optimizes sodium-glucose cotransport in the gut (the mechanism driving fluid absorption).

Homemade emergency alternative (if packets unavailable)

• 3.5 g (~½ teaspoon) NaCl
• 50 g precooked rice cereal or 6 teaspoons table sugar (sucrose)
• Supplement potassium separately via orange juice or coconut water

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