Final answer:
Thirst is a sign that dehydration has begun, a condition where water loss exceeds intake, leading to a variety of symptoms and potentially severe health complications. It is crucial to consume adequate fluids to prevent its onset and to recognize the early signs to avoid serious health risks.
Step-by-step explanation:
If a person feels thirsty, dehydration has already started. Dehydration indicates a condition where the loss of water exceeds the body's intake, resulting in a negative water balance. This can happen for various reasons, such as excessive water loss due to vomiting, prolonged diarrhea, sweating, or insufficient fluid intake. When about 2 percent of total body water is lost, signs and symptoms can become noticeable. It's important to recognize the symptoms of dehydration, which include thirst, dizziness, fainting, headaches, low blood-pressure, and fatigue. In severe cases, dehydration can lead to more serious complications such as loss of consciousness, coma, or even death.
There are different types of dehydration, with primary dehydration often occurring more quickly in environments with high temperatures, during fever, or in situations like desert travel. Furthermore, certain groups such as infants, endurance athletes, and older adults may be at a higher risk of dehydration due to body mass or reduced sensitivity of the thirst mechanism. Chronic dehydration has been linked to an increased risk of kidney stones, exercise-induced asthma, heart disease, and complications in people with diabetes.