The body's core temperature is controlled by the hypothalamus, the region of
the brain that also controls thirst, hunger, and sexual function. Under normal
conditions, the body dissipates excess heat, primarily through the skin and to a
lesser extent through the lungs. With heat exhaustion, body systems that
regulate temperature become overwhelmed and the body produces more heat than it
can dissipate. Approximately 380 deaths result from extreme temperatures each
year in the United States, with half of these deaths among people age 65 or
Signs and Symptoms
Heat exhaustion is accompanied by the following signs and
Fatigue and malaise
Fever (not exceeding 104°F)
Heavy sweating or no sweating at all
When body temperature exceeds 104°F, or if coma or seizure occurs, this
indicates that heat exhaustion has progressed to a condition called heat stroke.
Heat stroke is a much more serious condition, placing the individual at imminent
risk of cardiovascular collapse and death if not promptly reversed.
What Causes It?
Heat exhaustion results most frequently from exposure to high temperature,
accompanied by dehydration, usually from not drinking enough fluids. It also can
happen when large volumes of sweat are replaced with fluids that contain too
Who's Most At Risk?
The following factors increase the risk of developing heat
Age (the elderly and children under 5 years of age)
Illness or chronic disability
Physical exertion in hot environments (athletes, military personnel,
outdoor laborers are particularly at risk)
Being unaccustomed to a warm or humid environment
Medications that interfere with the body's heat-regulation system,
including antipsychotics, tranquilizers, antihistamines, tricyclic
antidepressants, and some over-the-counter sleeping
What to Expect at Your Provider's Office
If you are experiencing symptoms associated with heat exhaustion, you should
see your healthcare provider immediately. He or she will perform a physical
examination; check your blood pressure, pulse, and temperature; and assess your
level of dehydration. Lab tests of blood and urine samples may be needed.
Thirst is not a reliable indicator of impending dehydration; individuals
working and exercising in the heat, therefore, should drink plenty of fluids
before, during, and after the activity as well as adhere to the following
precautions to prevent heat exhaustion:
Stay in cool or air-conditioned environments when possible on hot
Increase fluid intake; drinking adequate fluids during exercise, for
example, prevents heat exhaustion and its complications including muscle damage
and kidney failure; dehydration can stress the heart and impair the kidneys'
ability to maintain the correct level of fluids and balance of electrolyte
(electrolytes are charged elements—like potassium,
sodium, phosporous and chloride—essential for the
normal function of every cell in the body); drinking fluids during exercise
helps to improve heart function, maintain kidney function, and lower the body's
Check on those vulnerable to heat exhaustion (the elderly, for
Avoid alcohol, caffeine and sugar which may all be dehydrating; drink
sports drinks that are sweetened with natural juices.
Exercise or work outdoors during cooler times of day.
Take cool baths.
Wear loose, lightweight clothing.
Athletes should consume 500 ml of fluids before an event and 200 to
300 ml at regular intervals.
According to the Centers for Disease Control and Prevention, long term
prevention of heat exhaustion includes regular, physician approved exercise;
novice athletes who are not well conditioned and suddenly participate in
prolonged, strenuous activities on a hot day may be at increased risk for heat
exhaustion and sudden kidney failure; those who participate in regular exercise
over time, allowing their bodies to adjust to hot conditions, may better
tolerate exercise on hot days.
The primary strategies for treating heat exhaustion are to rest in a cool
environment and to take in fluids. Water is adequate under most circumstances.
Healthcare providers may recommend saline electrolyte solutions, administered
orally for mild dehydration and intravenously in more severe
Oral or intravenous saline electrolyte solution may be used.
Complementary and Alternative
Most conventional healthcare providers recommend electrolytes in fluid
replacement products for people at risk of heat exhaustion (see
Prevention section for more details). Others also suggest that endurance
athletes take mineral supplements including:
Foods high in these nutrients include dark leafy greens, nuts, seeds, whole
grains, sea vegetables, blackstrap molasses, and bananas.
Although studies have not been conducted to look at the application for heat
exhaustion specifically, herbs traditionally used to reduce fever or lower body
Chinese skullcap (Scutellaria baicalensis)
- used in traditional Chinese medicine to reduce
temperature by dilating blood vessels near the surface of the skin which helps
Elder flower (Sambucus nigra) - used
to treat fever in Germany and Great Britain; used in combination with peppermint
leaf (Mentha x piperita) in the United States and Canada to treat
Subprostrata (Euchresta formosana) -
used in traditional Chinese medicine to reduce temperature by dilating blood
Willow bark (Salix spp.) -- used to treat fever in
Europe as well as by native Americans and eskimos
Yarrow (Achillea millefolium) - used
to treat fever in Great Britain and other parts of Europe as well as traditional
cultures in North America; also used as an Ayurvedic medicine
Also of note:
Cayenne pepper (Capsicum spp.) contains the ingredient
known as capsaicin that may lower body temperature by stimulating sweat glands;
many cultures, particularly those in hot climates, incorporate red pepper into
As with herbs, the use of homeopathic remedies has yet to be scientifically
investigated in the treatment of heat exhaustion. However, some common remedies
for overheating include:
Belladonna (Deadly nightshade) - often
used for fever, particularly if flushed with bright red skin and dulled
mentation; the person for whom this treatment is appropriate does not usually
feel thirsty even though his or her mouth and skin are dry
Glonoinum (Nitroglycerin) - used for
fever if the person is flushed and sweaty; the person for whom this is
appropriate may complain of a hot face but cold extremities, as well as
irritability, headache, and confusion.
An experienced homeopath would consider your individual case and may
recommend treatments to address both the underlying condition andany
Prognosis is good (24- to 48-hour recovery) if heat stroke is avoided. During
rehydration, clinicians will often check fluid and electrolyte levels to avoid
complications. Depending on the severity of heat exhaustion, this may require
Your healthcare provider will want to check the fluid levels in your body to
see if electrolyte replacement should be continued.
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Review Date: December 2000
Reviewed By: Participants in the review process include: Richard Glickman-Simon, MD,
Department of Family Medicine, New England Medical Center, Tufts University,
Boston, MA; Jacqueline A. Hart, MD, Department of Internal Medicine,
Newton-Wellesley Hospital, Harvard University and Senior Medical Editor
Integrative Medicine, Boston, MA.
The publisher does not accept any responsibility for the accuracy of
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