Introduction

Heat exhaustion occurs when your body gets too hot. The hypothalamus, the part of the brain that controls thirst and hunger, also controls the body's core temperature. Normally, the body cools itself by sweating. But if you are exposed to high temperatures for a long time (working outdoors in the summer, for example) and don't replace the fluids you lose, the body systems that regulate temperature become overwhelmed. As a result, your body produces more heat than it can release. Heat exhaustion requires immediate attention because it can progress to heat stroke, a life threatening illness.

Signs and Symptoms

People with heat exhaustion may experience the following signs and symptoms:

• Heavy sweating
• Fatigue
• Headache
• Pale, clammy skin
• Thirst
• Rapid heartbeat
• Dizziness, fainting
• Nausea, vomiting
• Muscle and abdominal cramps
• Mild temperature elevations

If body temperature goes above 104 degrees F, or if coma or seizure occurs, the patient may have heat stroke. Heat stroke can quickly lead to heart attack and death if not treated.

What Causes It?

Heat exhaustion occurs most often when you are exposed to high temperatures and become dehydrated, usually from not drinking enough fluids. It also can happen when large volumes of sweat are replaced with fluids that don't contain enough salt.

Who's Most At Risk?

The following factors increase the risk of developing heat exhaustion:

• Being dehydrated
• Age (the elderly and children under 5 years of age)
• Illness or chronic disability
• Obesity
• Pregnancy
• Cardiovascular disease
• Hypertension
• Respiratory disease
• Drinking alcohol
• Physical exertion in hot or humid environments (athletes, military personnel, and outdoor laborers are particularly at risk)
• Taking medications that interfere with the body's ability to cool itself, including antipsychotics, tranquilizers, antihistamines, tricyclic antidepressants, beta-blockers, and some over the counter sleeping pills

What to Expect at Your Provider's Office

If you have symptoms of heat exhaustion, you should see a doctor immediately. The doctor will perform a physical examination, check your blood pressure, pulse, and temperature, and assess how dehydrated you are. The doctor may also request lab tests of blood and urine samples.

Treatment Options

Prevention

If you are working or exercising in the heat, don't wait until you get thirsty to drink fluids. Instead, drink plenty of fluids before, during, and after the activity. Take the following precautions to prevent heat exhaustion:

• Stay in cool or air conditioned spaces when possible on hot days.
• Drink more fluids than usual. Drinking enough fluids during exercise, for example, helps improve heart function, maintain kidney function, and lower the body's core temperature. Dehydration can stress the heart and reduce the kidneys' ability to maintain the correct balance of electrolytes (charged elements -- such as potassium, sodium, phosphorous, and chloride -- which are essential for the normal function of every cell in the body).
• Check on those vulnerable to heat exhaustion (the elderly, for example).
• Avoid alcohol. Drink water or sports drinks sweetened with natural juices.
• Exercise or work outdoors during cooler times of day.
• Drink 2 cups of water 30 minutes before exercising and drink 1 cup of water every 20 minutes.
• Take cool baths.
• Wear loose, lightweight clothing.
• Long-term prevention of heat exhaustion includes regular, doctor approved exercise. Those who exercise regularly over time, allowing their bodies to adjust to hot conditions, may better tolerate exercise on hot days.

Treatment Plan

The primary treatment for heat exhaustion is to rest in a cool environment (a shady spot or, better, an air conditioned room) and to drink cool (not icy) fluids. Water is usually enough to reverse dehydration, or you can drink a sports drink that contains electrolytes. You can also cool down by spraying yourself with water and fanning.

Drug Therapies

Your health care provider may recommend an oral or intravenous saline electrolyte solution.

Complementary and Alternative Therapies

Nutrition and Supplements

Health care providers may recommend drinking fluids that contain electrolytes (see Prevention section). Endurance athletes may want to take mineral supplements, including:

• Calcium
• Magnesium
• Potassium

Foods high in these nutrients include dark leafy greens, nuts, seeds, whole grains, sea vegetables, blackstrap molasses, and bananas.

Herbs

The most important treatment for heat exhaustion is replacing lost fluids by drinking water or a sports drink. Some herbs may help, but if you have symptoms of heat exhaustion you should talk to your health care provider before taking anything. Although no studies have examined using herbs to treat heat exhaustion specifically, the following herbs may reduce fever or lower body temperature:

• Chinese skullcap (Scutellaria baicalensis) -- used in traditional Chinese medicine to reduce temperature by dilating blood vessels near the surface of the skin, which helps the body get rid of heat. Do not use Chinese skullcap if you are pregnant or nursing.
• Elder flower (Sambucusnigra) -- used to treat fever, sometimes combined with peppermint leaf (Mentha x piperita). Do not use Elder flower if you are pregnant or nursing.
• Willow bark (Salix spp.) -- used to treat fever. Do not take willow bark if you are allergic to aspirin, and do not give it to children under 16 because of the risk of developing Reye syndrome, a serious illness. Do not use Willow bark if you are pregnant or nursing. Use caution if you have an illness that is sometimes aggravated by aspirin, as it may also be aggravated by willow bark. Such conditions include asthma, stomach ulcers, diabetes, gout, hemophilia, hypoprothrombinemia, kidney and liver disease. Like aspirin, Willow bark can have a blood thinning effect and should not be taken with other blood thinning medications and should be discontinued well in advance of any surgery.
• Yarrow (Achillea millefolium) -- used to treat fever. Do not take Yarrow if you are pregnant or nursing. Yarrow can have blood thinning effects and should not be taken with other blood thinning medications, such as coumadin (warfarin), and should be discontinued at least 2 weeks prior to any surgery. Yarrow can interact with lithium and other sedative medications.
• Cayenne pepper (Capsicum spp.) -- contains capsaicin, which may lower body temperature by stimulating sweat glands. Talk to your doctor if you are taking blood thinning medications, as cayenne pepper can have blood thinning effects.

Homeopathy

Although few studies have examined the effectiveness of specific homeopathic therapies, professional homeopaths may consider the following remedies for the treatment of fevers based on their knowledge and experience. Before prescribing a remedy, homeopaths take into account a person's constitutional type -- your physical, emotional, and psychological makeup. An experienced homeopath assesses all of these factors when determining the most appropriate treatment for each individual.

• Belladonna -- often used for fever, particularly if flushed with bright red skin and dulled mental activity. This treatment is appropriate for people who are not thirsty even though their mouths and skin are dry.
• Glonoinum -- used for fever if the person is flushed and sweaty. It's appropriate for people who complain of a hot face but cold extremities, as well as irritability, headache, and confusion. Homeopaths often recommend this treatment for ailments brought on by overexposure to the sun.

Prognosis/Possible Complications

If you avoid heat stroke, recovering from heat exhaustion usually takes 24 - 48 hours. Depending on the severity of heat exhaustion, you may be hospitalized so doctors can monitor your fluid and electrolyte levels to avoid complications.

Following Up

Your health care provider will want to check the fluid levels in your body to see if electrolyte replacement should be continued.