Dehydration is a medical condition in which the amount of water in the body is insufficient for normal bodily functions. Conditions and diseases that can lead to dehydration include diarrhea, vomiting, hyperthermia, cholera and yellow fever. Symptoms of dehydration include loss of appetite, dryness of skin, fatigue, increase in heart rate, low blood pressure, and dizziness. Treatment includes restoring the amount of water and electrolytes that have been lost.