Oral rehydration therapy

What the evidence says

WHO counts diarrheal disease as the third leading cause of death in children aged 1 to 59 months, and puts the toll at about 443,832 children under five each year. Oral rehydration therapy (ORT) replaces lost fluids by mouth, with oral rehydration salts (ORS), which cost a few cents per treatment, or with recommended home fluids.

As a treatment, ORT is about as good as a drip for most children. A Cochrane review of 17 trials with 1,811 children found no clinically important differences between oral and intravenous rehydration. Oral treatment failed for about 5 percent of children, who then needed a drip, against about 1 percent with intravenous rehydration, and children treated orally left the hospital about a day sooner. A second Cochrane review found that a reduced-osmolarity solution, less concentrated than the older WHO formula, led to fewer unplanned drips, less stool and less vomiting.

The effect on deaths is estimated rather than measured, because no one can ethically withhold treatment in a trial. Munos and colleagues (2010) estimated that ORS may prevent 93 percent of diarrhea deaths, by projecting a 69 percent reduction seen in three quasi-experimental studies out to full coverage. A 2020 mapping study noted that estimates like this rest on limited evidence, and it tested a much smaller effect in a sensitivity analysis. The strong grade applies to ORT’s core outcome, treating dehydration. The number of lives it saves is less certain.

Two facts temper the picture. WHO says other causes, such as bacterial infections, likely account for a growing share of diarrhea deaths, which rehydration alone does not treat. And use still lags: in low- and middle-income countries, the share of children with diarrhea who got ORS rose only from 34 percent in 2000 to 44 percent in 2016.

Where it sits on the depth scale

Charitology places ORT at relief (depth 0), not prevention. It treats a child who is already sick, one episode at a time. The diarrhea still happens. WHO lists the measures that prevent it: safe drinking water, improved sanitation, handwashing with soap, exclusive breastfeeding, good hygiene and rotavirus vaccination. Relief at this price and scale is not a lesser category. Because it works at home, ORT can reach children far from any hospital.

Open questions

• Why does a treatment this cheap reach fewer than half the children who need it? See the history of how ORT spread and the Story Bias.
• As the causes of diarrhea deaths shift, how much of ORT’s historical effect still applies?
• Charitology has not found a reliable published per-dollar estimate of lives saved by ORT alone, so this entry has no Impact Calculator figure.