Symptoms:
Thirst is generally the first symptom of heat exhaustion, followed by general malaise, weakness, tiredness, a loss of appetite, headache, pallor, dizziness, and a general flulike feeling that may include nausea and even vomiting. Sometimes the heart races and concentration becomes more difficult.

Heat exhaustion is less severe than heat stroke, and may occur over several days out in the sun. Dehydration may eventually lead to blood volume loss, poor heat regulation, and shock.

Cause:
Heat exhaustion is generally caused by water depletion (dehydration), and more rarely by a lack of salt in the diet (salt depletion). When we sweat, we lose both water and salt (as well as potassium and sodium).

Treatment:
• First, get out of the sun, so the body temperature will not continue to rise and the body will not lose more water and salt. If you remain in the sun, even though resting and drinking fluids, your temperature will continue to rise! Do not return to the sun for many hours!

• In the early stages, drink large amounts of mineral-rich vegetable and fruit juices to replace water and electrolyte loss in perspiration. Water, by itself, does not replace electrolytes. Potassium-rich vegetable broths are helpful.

Prevention:
Plan ahead, so you will not come down with heat stroke later:

• Drink water. Drink diluted electrolyte drinks. Avoid salt tablets. They do the opposite of what they are supposed to do. The increased salt in the stomach keeps fluids there longer.

• Do not use caffeine, alcohol, or tobacco. The first two accelerate dehydration, and the smoking constricts blood vessels.

• Over several days' time, adapt yourself slowly to the sun. Do not overexert when out in it. Avoid working in the mid-day. Wear a hat, and keep on a light-colored shirt.

• Pour water over your head and shirt, especially if the air is not humid. Keep drinking lots of water.