Take a Hike in Southern California

from the Mayo Clinic

Heat exhaus­tion is a con­di­tion whose symp­toms may include heavy sweat­ing and a rapid pulse, a result of your body over­heat­ing. It’s one of three heat-related syn­dromes, with heat cramps being the mildest and heat­stroke being the most severe.

Causes of heat exhaus­tion include expo­sure to high tem­per­a­tures, par­tic­u­larly when com­bined with high humid­ity, and stren­u­ous phys­i­cal activ­ity. With­out prompt treat­ment, heat exhaus­tion can progress to heat­stroke, a life-threatening con­di­tion. For­tu­nately, heat exhaus­tion is preventable.

Symp­toms
Signs and symp­toms of heat exhaus­tion may come on sud­denly and resem­ble those of being in shock. Your skin may feel hot and moist and appear flushed. Other pos­si­ble heat exhaus­tion symp­toms include:

• Heavy sweat­ing
• Faint­ness
• Weak, rapid pulse
• Low blood pressure
• Nau­sea
• Low-grade fever
• Headache
• Dark urine

Causes
Your body’s heat com­bined with envi­ron­men­tal heat results in what’s called your core tem­per­a­ture — your body’s inter­nal tem­per­a­ture. Your body needs to reg­u­late the heat gain (and in cold weather, heat loss) from the envi­ron­ment to main­tain a core tem­per­a­ture that’s nor­mal, approx­i­mately 98.6 F (37 C).

• Impaired cool­ing mech­a­nism – In hot weather, your body cools itself mainly by sweat­ing. The evap­o­ra­tion of your sweat reg­u­lates your body tem­per­a­ture. How­ever, when you exer­cise stren­u­ously or oth­er­wise overex­ert in hot, humid weather, your body is less able to cool itself efficiently.

As a result, your body may develop heat cramps, the mildest form of heat-related ill­ness. Signs and symp­toms of heat cramps usu­ally include heavy sweat­ing, fatigue, thirst and mus­cle cramps. Prompt treat­ment usu­ally pre­vents heat cramps from pro­gress­ing to heat exhaustion.

You usu­ally can treat heat cramps by drink­ing flu­ids con­tain­ing elec­trolytes (such as Gatorade or other sports drinks), get­ting into cooler tem­per­a­tures, such as an air-conditioned or shaded place, and resting.

Other causes
Besides hot weather and stren­u­ous activ­ity, other causes of heat exhaus­tion include:

• Dehy­dra­tion, which impedes your body’s abil­ity to sweat and main­tain a nor­mal temperature
• Alco­hol use, which can affect your body’s abil­ity to reg­u­late your temperature
• Over­dress­ing, par­tic­u­larly in clothes that don’t allow sweat to evap­o­rate easily

When to seek med­ical advice
If you think you’re expe­ri­enc­ing heat exhaus­tion, then first try to cool off by:

• Mov­ing to a cooler place
• Drink­ing cool water or sports drinks
• Rest­ing with your legs ele­vated above heart level
• Con­tact your doc­tor if your signs or symp­toms worsen or if they don’t improve within 30 min­utes. Seek imme­di­ate med­ical atten­tion if your body tem­per­a­ture reaches 104 F (40 C) or higher.

Com­pli­ca­tions
Untreated, heat exhaus­tion can progress to heat­stroke, a life-threatening con­di­tion that occurs when your body tem­per­a­ture reaches 104 F (40 C) or higher. Heat­stroke requires imme­di­ate med­ical atten­tion to pre­vent per­ma­nent dam­age to your brain and other vital organs or death.

Treat­ments and drugs
In most cases, you can treat heat exhaus­tion your­self by doing the following:

• Rest in a cool place. Get­ting into an air-conditioned build­ing is best, but at the least, find a shady spot. Rest on your back with your legs ele­vated higher than your heart level.
• Drink cool flu­ids. Stick to water or sports drinks. Don’t drink any bev­er­ages that have alco­hol or caf­feine, either of which can con­tribute to fluid loss.
• Apply cool water to your skin. If pos­si­ble, take a cool shower or soak in a cool bath. Don’t use alco­hol on your skin.
• Loosen cloth­ing. Remove any unnec­es­sary cloth­ing and make sure your clothes aren’t binding.
• If you don’t begin to feel bet­ter within a half-hour using these treat­ment mea­sures, seek prompt med­ical atten­tion. You may be given intra­venous (IV) flu­ids to help you rehy­drate. Immer­sion in cold water, mist­ing your skin, and plac­ing you in front of fans or using cold or ice packs and cool­ing blan­kets are some of the tech­niques that may be used to bring down your body temperature.

Pre­ven­tion
You can take a num­ber of pre­cau­tions to pre­vent heat exhaus­tion and other heat-related ill­nesses. When tem­per­a­tures climb, remem­ber to:

• Wear loos­e­fit­ting, light­weight, light-colored cloth­ing. Excess, dark or tight cloth­ing holds in heat and doesn’t let your body cool prop­erly because it inhibits sweat evaporation.
• Avoid sun­burn. If you’re going to be out­doors, wear a light­weight, wide-brimmed hat or use an umbrella to pro­tect your­self from the sun, and apply sun­screen to any exposed skin. Hav­ing a sun­burn reduces your body’s abil­ity to rid itself of heat.
• Seek a cooler place. Being in an air-conditioned build­ing, even for just a few hours, is one of the best ways to pre­vent heat exhaus­tion. If your home doesn’t have an air con­di­tioner, con­sider spend­ing time at a library or shop­ping mall. At the least, find a well-shaded spot. Fans alone aren’t ade­quate to counter high heat and humidity.
• Drink plenty of flu­ids. Stay­ing hydrated will help your body sweat and main­tain a nor­mal body temperature.
• Take extra pre­cau­tions with cer­tain med­ica­tions. Ask your doc­tor or phar­ma­cist whether the med­ica­tions you take make you more sus­cep­ti­ble to heat exhaus­tion and, if so, what you can do to keep your body from overheating.
• Avoid hot spots. When parked in the sun, your car can reach a tem­per­a­ture of more than 160 F (71 C). Let the car cool off before you drive it. Never leave chil­dren or any­one else in a parked car in hot weather for any period of time.
• It’s best not to exer­cise or engage in any stren­u­ous activ­ity in hot weather, but if you must, fol­low the same pre­cau­tions and rest fre­quently in a cool spot. Tak­ing breaks and replen­ish­ing your flu­ids dur­ing that time will help your body reg­u­late your temperature.

If you’re oth­er­wise healthy, your body can adapt to heat after sev­eral weeks, and its abil­ity to reg­u­late its tem­per­a­ture becomes more effi­cient. You’ll still need to take pre­cau­tions, but work­ing or exer­cis­ing in heat should become more tolerable.

If you are on the trail, I would add:

• Don’t move him or her until they are cooled down.
• Never leave the per­son alone in this condition.
• If the con­di­tion per­sists, get word to emer­gency services.

If any of you out there have ever expe­ri­enced heat exhaus­tion on a hike in South­ern Cal­i­for­nia or was with some­one who has, please let us know how it went and whether you have some addi­tional tips you can share with us.

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