When children die from diarrhea, the cause is often dehydration (losing too much water from the body). Because diarrhea is watery, it takes away a lot of the water. It also takes away electrolytes—important salts that the body needs to survive. Dehydration is extra dangerous for small children because they have less water in their bodies to begin with. This means they cannot lose as much water as adults before they start to have serious health problems.