Your chances of becoming a heat casualty as a survivor are great, due to injury, stress and lack of critical items of equipment. Following are the major types of heat casualties and their treatment when little water and no medical help are available.
The loss of salt due to excessive sweating causes heat cramps. Symptoms are moderate to severe muscle cramps in legs, arms or abdomen. These symptoms may start as a mild muscular discomfort. You should now stop all activity, get in the shade and drink water. If you fail to recognize the early symptoms and continue your physical activity, you will have severe muscle cramps and pain. Treat as for heat exhaustion, below.
A large loss of body water and salt causes heat exhaustion. Symptoms are headache, mental confusion, irritability, excessive sweating, weakness, dizziness, cramps and pale, moist, cold (clammy) skin. Immediately get the patient under shade. Make him lie on a stretcher or similar item about 45 centimeters off the ground. Loosen his clothing. Sprinkle him with water and fan him. Have him drink small amounts of water every three minutes. Ensure he stays quiet and rests.
A severe heat injury caused by extreme loss of water and salt and the body’s inability to cool itself. The patient may die if not cooled immediately. Symptoms are the lack of sweat, hot and dry skin, headache, dizziness, fast pulse, nausea and vomiting, and mental confusion leading to unconsciousness. Immediately get the person to shade. Lay him on a stretcher or similar item about 45 centimeters off the ground. Loosen his clothing. Pour water on him (it does not matter if the water is polluted or brackish) and fan him. Massage his arms, legs and body. If he regains consciousness, let him drink small amounts of water every three minutes.
Information courtesy of the U.S. Army Survival Manual