Dehydration occurs when the body uses or loses more fluid than it takes in. Then the body doesn't have enough water and other fluids to do its usual work. Not replacing lost fluids leads to dehydration. Anyone can become dehydrated. But the condition is more serious for infants, children and older adults. The most common cause of dehydration in young children is diarrhea and vomiting. Older ...
Dehydration may be subtle, causing a lingering headache and tiredness or other symptoms. Learn how to rehydrate if you are dehydrated.