Heat Illness, Signs & Treatment
Found on the Internet, Reviewed and Updated by David Mosley

Heat illnesses are the result of elevated body temperatures due to an inability to dissipate the body's heat and/or a decreased fluid level. Always remember that mild heat illnesses have the potential of becoming severe life threatening emergencies if not treated properly. 

Heat Cramps:  Heat cramps are a form of muscle cramp brought on by exertion and insufficient salt. 

Heat Cramps Treatment:  Replace fluid and stretch the muscle Kneading and pounding the muscle is less effective than stretching and probably contributes to residual soreness. 

Heat Syncope:  Heat Syncope (fainting) is a mild form of heat illness, which results from physical exertion in a hot environment. In an effort to increase heat loss, the skin blood vessels dilate to such an extent that blood flow to the brain is reduced, resulting in symptoms of faintness, dizziness, headache, increased pulse rate, restlessness, nausea, vomiting, and possibly even a brief loss of consciousness. Inadequate fluid replacement, which leads to dehydration, contributes significantly to this problem.  

Heat Syncope Treatment:  Heat Syncope should be treated as fainting. The person should lie or sit down, preferably in the shade or in a cool environment. Elevate the feet and give fluids – doctors usually recommend you to drink equal amounts of Gatorade type drinks and water. Either alternate Gatorade and water, or dilute the Gatorade 50/50 with water. The patient should not engage in vigorous activity for at least the rest of that day. Only after he/she has completely restored his/her body fluids and has a normal urinary output should any exercise in a hot environment be resumed (and then cautiously). 

Heat Exhaustion:  This occurs when fluid losses from sweating and respiration are greater than internal fluid reserves (volume depletion). Heat Exhaustion is really a form of volume shock. The lack of fluid causes the body to constrict blood vessels especially in the periphery (arms and legs). To understand Heat Exhaustion think of a car with a radiator leak pulling a trailer up a mountain pass. There is not enough fluid in the system to cool off the engine so the car overheats. Adding fluid solves the problem.  

The signs and symptoms of Heat Exhaustion are:

  • Sweating

  • Skin - Pale, clammy (from peripheral vasoconstriction)

  • Pulse – Increased

  • Respirations – Increased

  • Temperature - normal or slightly elevated

  • Urine Output – Decreased

  • Patient feels weak, dizzy, thirsty, "sick," anxious

  • Nausea and vomiting (from decreased circulation in the stomach)

Heat Exhaustion Treatment:  Victims of Heat Exhaustion must be properly re-hydrated and must be very careful about resuming physical activity (it is best to see a physician before doing so). Treatment is as described above for Heat Syncope, but the person should be more conservative about resuming physical activity to give the body a chance to recover. Have the person rest (lying down) in the shade and follow the treatment as described above.  Drink slowly, drinking too much, too fast very often causes nausea and vomiting. 

Evacuation usually is not necessary. Heat Exhaustion can become Heat Stroke if not properly treated (see Heat Stroke below). A victim of Heat Exhaustion should have be closely monitored to make sure that their temperature does not go above 103° F (39° C) If it does so, treat the person for Heat Stroke as described below.  

Heat Stroke - Hyperthermia:  Heat Stroke is one of the few life threatening medical emergencies. A victim can die within minutes if not properly treated. Heat Stroke is caused by an increase in the body's core temperature. Core temperatures over 105° (41° C) can lead to death. The rate of onset of Heat Stroke depends on the individual's fluid status. To understand Heat Stroke think of that same car pulling a trailer up a mountain pass on a hot day. This time the radiator has plenty of fluid, but the heat challenge of the engine combined with the external temperature is too much. The engine can't great rid of the heat fast enough and the engine overheats. There are two types of Heat Stroke-fluid depleted (slow onset) and fluid intact (fast onset).

  • Fluid depleted - The person has Heat Exhaustion due to fluid loss from sweating and/or inadequate fluid replacement, but continues to function in a heat challenge situation. Ultimately, the lack of fluid has minimized the body's active heat loss capabilities to such an extent that the internal core temperature begins to rise. Example: a cyclist on a hot day with limited water.

  • Fluid intact (fast onset) - The person is under an extreme heat challenge. The heat challenge overwhelms the body's active heat loss mechanisms even though the fluid level is sufficient. Example: a cyclist pushing hard on a 104° F day (40° C).

Signs & Symptoms of Heat Stroke:

  • The key to identifying Heat Stroke is hot skin. Some victims may have hot, dry skin; others may have hot, wet skin because they have just moved from Heat Exhaustion to Heat Stroke.

  • Peripheral vasoconstriction (skin gets pale)

  • Pulse Rate – increased

  • Respiratory Rate – increased

  • Urine Output – decreased

  • Temperature - increased (may be over 105° F/41° C)

  • Skin - may be wet or dry, flushed

  • AVPU - Severe changes in mental status and motor/sensory changes, then the person may become comatose, possibility of seizures.

  • Pupils - may be dilated and unresponsive to light

 Heat Stroke Treatment:

  • Efforts to reduce body temperature must begin immediately! Move the patient (gently) to a cooler spot or shade the victim. Remove clothing. Pour water on the extremities and fan the person to increase air circulation and evaporation. Or cover the extremities with cool wet cloths and fan the patient. Immersion in cool (not cold) water is also useful. During cooling the extremities should be massaged vigorously to help propel the cooled blood back into the core.

  • After the temperature has been reduce to 102° F (39° C), active cooling should be reduced to avoid hypothermia (shivering produces more heat). The patient must be monitored closely to make sure that temperature does not begin to go up again.

  • Volume replacement - the victim will probably need fluid regardless of the type of onset.

  • Basic life support, CPR if needed.

Heat Stroke is life threatening. If the person exhibits signs of heat stroke, particularly if the skin is hot to the touch, the situation is critical. Immediate cooling is required and they should be transported to a hospital as soon as possible. 

Heat stroke can also mess up your body's thermoregulation. So you have to watch that you don't overcool and throw them into hypothermia. (It can take several days for your thermoregulation to return to normal. Some never do though.) 

If you have cold packs apply them to the neck, arm pits, and groin. 

If the patient is unresponsive or has an altered mental state or is vomiting do not give them anything to drink. This may induce more vomiting and increase the risk of aspiration. Position them in what is called the "Recovery Position". On their side, knees slightly bent, with their head supported in a neutral position. If the patient also has a suspected spinal injury, do not use this position. 

If the patient is responsive, has moist, pale skin, is not hot to the touch and is not nauseated you may encourage fluids. Put them in the "Trendelenburg" position. Body supine with feet elevated about a foot above the head. 

In either situation you have to monitor the patient’s airway and respiration. 

**One more thing, don't wait to feel thirsty to take a drink. The best way to stay hydrated is to carry a bottle of water with you and sip on it frequently. If you are out in the heat take a break about every 1/2 hour to cool off and take a drink. In our humid climate, it is harder to dissipate the heat. The body sweats, but it doesn't evaporate fast enough to get the needed cooling effect.  Also, stay away from alcohol, it will dehydrate you more.