Heat exhaustion: This condition often occurs when people exercise (work or play) in a hot, humid place and body fluids are lost through sweating, causing the body to overheat. The person’s temperature may be elevated, but not above 104°F.

Heat stroke: This medical condition is life-threatening. The person’s cooling system, which is controlled by the brain, stops working and the internal body temperature rises to the point where brain damage or damage to other internal organs may result (temperature may reach 105+°F).

Heat Exhaustion and Heat Stroke Causes

Heat exhaustion is typically caused when people who are not well adjusted to heat exercise in a hot, humid environment.

·       At high temperatures, the body cools itself largely through evaporation of sweat.

·       When it is very humid, this mechanism does not work properly.

·       The body loses a combination of fluids and salts (electrolytes).

·       When this is accompanied by an inadequate replacement of fluids, disturbances in the circulation may result that are similar to a mild form of shock.

·      Heat stroke may often develop rapidly.

·       Medical conditions or medications that impair the body’s ability to sweat may predispose people to this problem.

Heat stroke happens in the following two ways:

·       The classic form occurs in people whose cooling mechanisms are impaired.

·       The exertional form occurs in previously healthy people who are undergoing strenuous activity in a hot environment.

·       Infants and the elderly are more likely to have this problem,as are those who are taking antihistamines and certain types of medication for high blood pressure or depression.

Heat Exhaustion and Heat Stroke Symptoms

Heat exhaustion symptoms

·       Often pale with cool, moist skin

·       Sweating profusely

·       Muscle cramps or pains

·       Feels faint or dizzy

·       Vertigo

·       May complain of headache, weakness, thirst, and nausea

·       Core (rectal) temperature elevated-usually more than 100°F-and the pulse rate increased  Note: Ride leaders don’t carry or use rectal thermometers……everJ

Heat stroke symptoms

·       Unconscious or has a markedly abnormal mental status (dizziness, confusion, hallucinations, or coma)

·       Flushed, hot, and dry skin (although it may be moist initially from previous sweating or from attempts to cool the person with water)

·       May have slightly elevated blood pressure at first that falls later

·       May be hyperventilating

·       Rectal (core) temperature of 105°F or more

When to Seek Medical Care

As with all other medical problems, a doctor should be called if you are not sure what is wrong, if you do not know what to do for the problem, or if the person is not responding to what you are doing for them.  Call a doctor for heat exhaustion if the person is unable to keep fluids down or if their mental status begins to deteriorate. Symptoms of shortness of breath, chest pain, or abdominal pain may indicate that the heat exhaustion is accompanied by more serious medical problems.

Suspected heat stroke is a true, life-threatening medical emergency. Call for an ambulance and request information as to what to do until the ambulance arrives.

·       A person with suspected heat stroke should always go to the hospital (or call for an ambulance) at once.

·       For heat exhaustion, a person should go to the hospital if any of the following are present:

·       Loss of consciousness, confusion, or delirium

·       Chest or abdominal pain

·       inability to drink fluids

·       Continuous vomiting

·       Temperature more than 104°F

·       Temperature that is rising despite attempts to cool the person

·       Any person with other serious ongoing medical problems

Exams and Tests

For a heat exposure emergency, the treating doctor needs some important information:

·       Past medical history

·       Medicines the patient is currently taking (prescription and over-the-counter)

·       Symptoms the patient is experiencing

·       Blood tests to check for organ damage may be indicated, however, no specific radiologic (imaging) tests are necessary.

·       Heat Exhaustion and Heat Stroke Treatment

Self-Care at Home

Home care is appropriate for mild forms of heat exhaustion. Heat stroke is a medical emergency, and an ambulance should be called immediately.

·       For mild cases of heat exhaustion

·       Rest in a cool, shaded area.

·       Give cool fluids such as water or sports drinks (that will replace the salt that has been lost). Salty snacks are appropriate as tolerated.

·       Loosen or remove clothing.

·       Apply cool water to skin.

·       Do not use an alcohol rub.

·       Do not give any beverages containing alcohol or caffeine.

Heat stroke (do not attempt to treat a case of heat stroke at home, but you can help while waiting for medical assistance to arrive.) 

·       Call 911 immediately

·       Move the person to a cooler environment, or place him or her in a cool bath of water (as long as he or she is conscious and can be attended continuously).

·       Alternatively, moisten the skin with lukewarm water and use a fan to blow cool air across the skin.

·       Give cool beverages by mouth only if the person has a normal mental state and can tolerate it.

·       Medical Treatment

·       The treatment is directed at cooling the patient in a controlled fashion while making sure that the patient stays hydrated and that their blood flow is normal.

Treatment of heat exhaustion

·       Because heat exhaustion generally develops gradually, a person will often be dehydrated. Usually they may be given something to drink, and a cool sport beverage (with 6% or less glucose) should be used. IV fluid may be used if the person does not tolerate oral replacement (if he or she cannot keep anything down).

·       The patient should stay in a cool environment and avoid strenuous activity for several days.

Treatment of heat stroke

·       Treatment is aimed at reducing the patient’s core temperature to normal as quickly as possible.

·       The doctor may use immersion, evaporative, or invasive cooling techniques.

·       In the evaporative technique, cold or ice packs may be placed in the armpits or groin. The skin is kept moist with cool fluid, and fans are directed to blow across the body.

·       An IV will be started and fluids are given rapidly.

·       The patient’s urine output will be monitored.

·       Treatment will continue until the patient’s body core temperature is 101.3-102.2°F (38.5-39°C) and then stopped to keep from making the patient too cold.

·       The patient most likely be admitted to the hospital for further blood tests and observation.

·       Follow-up

·       Before leaving the doctor’s office or hospital, be sure the patient understands the instructions that are given by the physician, in particular the information regarding work and activity restrictions. Make sure the patient has a cool environment and plenty of suitable beverages (without alcohol or caffeine).


·       Avoid heat exhaustion by not engaging in strenuous activity in hot, humid environments. People who are not used to the heat should be particularly careful. Intersperse periods of rest in a cool environment with plenty of available fluids to drink. Avoid strenuous activities during the hottest part of the day.

·       Heat stroke often occurs in people who are unable to modify their environments: infants, the elderly, and bed-ridden people. People who are taking many types of blood pressure, allergy, or depression medication may also be particularly at risk and should avoid hot environments.

·       People in supervisory positions such as coaches, trainers, and lifeguards should be trained to specifically recognize signs of heat illness and what preventive measures to take.


The prognosis is related to the severity of the heat exposure and the patient’s general medical condition. The very young and the very old have the worst outcomes. In general, the prognosis with heat exhaustion is excellent, with full recovery expected. However, with heat stroke, permanent nerve, heart, liver, or kidney problems, or even death, can occur.


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