Dehydration is the deficiency of fluid in your body which occurs when the body loses more water than it takes in. Feeling thirsty is the most obvious sign that you’re dehydrated and that your body doesn’t have enough fluid to function properly. Loss of fluid can be caused by too much sweating due to heat or overexertion vomiting diarrhea or urinating frequently. Certain health conditions including diabetes may also make you more prone to dehydration. Most people are prone to acute dehydration which can be resolved by resting and drinking water. But sometimes dehydration recurs for longer periods regardless of