Dehydration and Diarrhea Dehydration is a loss of body fluids, which are made up of water and salts. When sick children vomit or have diarrhea, they can lose large amounts of water from their bodies and can become dehydrated very quickly. Diarrhea is a very common problem in childhood. Usually, it is mild and brief. Sometimes, it can be severe, especially in infants.
Rehydration Project Diarrhoea causes dehydration, which kills approximately 2.2 million children every year. Children are more likely than adults to die from diarrhoea because they become dehydrated more quickly.