Hyperthermia is the general name given to a variety of heat-related illnesses.


Warm weather and outdoor activity go hand in hand. However, it is important for older people to take action to avoid the severe health problems often caused by hot weather.


Regardless of extreme weather conditions, the healthy human body keeps a steady temperature of 98.6 degrees Fahrenheit.

In hot weather or during vigorous activity, the body perspires. As this perspiration evaporates from the skin, the body is cooled.

If challenged by long periods of intense heat, the body may lose its ability to respond efficiently. When this occurs, a person may experience hyperthermia. In other words, hyperthermia occurs when body metabolic heat production or environmental heat load exceeds normal heat loss capacity or when there is impaired heat loss.

Health Factors That Increase Risk

The temperature does not have to hit 100 degrees for a person to be at risk. Both one's general health and/or lifestyle may increase a person's chance of suffering a heat-related illness.

Health factors which may increase risk include:

  • poor circulation

  • inefficient sweat glands, and changes in the skin caused by the normal aging process

  • heart, lung and kidney diseases, as well as any illness that causes general weakness or fever high blood pressure or other conditions that require changes in diet

For example, people on salt-restricted diets may increase their risk of being unable to perspire, caused by medications including diuretics, sedatives and tranquilizers, and certain heart and blood pressure drugs.

Other factors include being substantially overweight or underweight, and drinking alcoholic beverages.

Lifestyle factors that can increase risk are:

  • unbearably hot living quarters

  • lack of transportation - which prevents people from seeking respite from the heat in shopping malls, movie houses, and libraries

  • overdressing - because they may not feel the heat, older people may not dress appropriately in hot weather

  • visiting overcrowded places - trips should be scheduled during non-rush hour times

  • not understanding weather conditions - older persons at risk should stay indoors on especially hot days.


The two most common forms of hyperthermia are heat exhaustion and heat stroke. Of the two, heat stroke is especially dangerous and requires immediate medical attention.

Heat stress occurs when a strain is placed on the body as a result of hot weather.

Heat fatigue is a feeling of weakness brought on by high outdoor temperature. Symptoms include cool, moist skin and a weakened pulse. The person many feel faint.

Heat syncope is a sudden dizziness experienced after exercising in the heat. The skin appears pale and sweaty but is generally moist and cool. The pulse is weakened and the heart rate is usually rapid. Body temperature is normal.

Heat cramps are painful muscle spasms in the abdomen, arms or legs following strenuous activity. Heat cramps are caused by a lack of salt in the body.

Heat exhaustion is a warning that the body is getting too hot. The person may be thirsty, giddy, weak, uncoordinated, nauseated and sweating profusely. The body temperature is normal and the pulse is normal or raised. The skin is cold and clammy.

Heat stroke can be life-threatening and victims can die. A person with heat stroke usually has a body temperature above 104 degrees Fahrenheit. Other symptoms include confusion, combativeness, bizarre behavior, faintness, staggering, strong and rapid pulse, and possible delirium or coma. High body temperature is capable of producing irreversible brain damage.


Diagnosis is based on the medical history (including symptoms) and physical exam.


If the victim is exhibiting signs of heat stroke, emergency assistance should be sought immediately. Without medical attention, heat stroke can be deadly.

Heat exhaustion may be treated in several ways:

  • get the victim out of the sun into a cool place, preferably one that is air conditioned

  • offer fluids but avoid alcohol and caffeine - water and fruit juices are best

  • encourage the individual to shower and bathe, or sponge off with cool water

  • urge the person to lie down and rest, preferably in a cool place


Prevention hyperthermia is relatively straightforward: Use common sense in avoiding excessive activity in situations in which heat is present. Adequate intake of fluids before, during and after exercise in any situation also is essential.