Dehydration means your body does not have as much water and fluids as it should. Dehydration can be caused by losing too much fluid, not drinking enough water or fluids, or a combination of both. The most common cause of dehydration in infants and children is loss through vomiting and diarrhea from a virus.

Because of their smaller body weights and higher turnover rates for water and electrolytes, infants and children are more susceptible to dehydration than adults. The elderly and those with an illness are also at higher risk.

Dehydration is classified as mild, moderate, or severe based on the percentage of body weight lost. When severe, dehydration is a life-threatening emergency.

Your body may lose too much fluids from:

• Vomiting or diarrhea
• Excessive urine output, such as with uncontrolled diabetes or diuretic use
• Excessive sweating (for example, from exercise)
• Fever

• Nausea
• Loss of appetite due to illness
• Sore throat or mouth sores

Dehydration in sick children is often a combination of both -- refusing to eat or drink anything while also losing fluid from vomiting, diarrhea, or fever.