Oral versus intravenous rehydration for treating dehydration due to gastroenteritis in children

This Cochrane review, the gold standard of evidence summaries, pooled 17 clinical trials comparing oral rehydration solutions with IV fluids in children dehydrated by gastroenteritis.

IV therapy failed slightly less often, roughly 4 fewer failures per 100 children, but for the vast majority, drinking rehydration solution worked just as well and got them out of the hospital sooner.

There were no meaningful differences in weight gain, sodium balance, or how long the illness lasted. Each route had its own side effects: IV lines caused more vein inflammation, oral rehydration more temporary bowel sluggishness.

The honest bottom line: IV fluids rehydrate reliably and quickly, and they matter most when drinking is not possible or has not worked.