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How Long Does Heat Exhaustion Last?

written by: Finn Orfano • edited by: KJ Fitness,Ink • updated: 4/30/2009

How long does heat exhaustion last? Because of the toll it takes on your body’s delicate cooling systems, heat exhaustion can lay you up for a while.

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    What is heat exhaustion?

    Heat exhaustion is a mild heat-related illness that occurs when the body overheats due to dehydration and an inability to cool off in hot weather.

    When the temperature and humidity rise, the risk for heat exhaustion is great. Certain factors may make a person even more at risk for developing the illness:

    • High blood pressure
    • Illness
    • Obesity
    • Age (both young children and older adults are at higher risk)
    • Being dehydrated
    • Pregnancy
    • Drinking alcoholic beverages
    • Taking certain prescription medications that interfere with the body’s ability to cool itself (Examples include sleeping pills, antihistamines, and antidepressants.)

    Left untreated, heat exhaustion can develop into heat stroke—which can be fatal.

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    The Physiology of Heat Exhaustion

    Heat exhaustion is so dangerous because it throws off the body’s normal cooling systems. Normally, the body regulates its temperature through two mechanisms: sweating and vasodilation.

    Under normal conditions, sweating cools us by releasing moisture through the skin’s surface. As air carries the sweat away, we feel cooler.

    During vasodilation, veins and capillaries expand, and blood flow to the outer layers of the skin increases. Body heat carried in the blood radiates out from these outer layers, releasing into the environment.

    But during heat exhaustion, extreme weather conditions put so much stress on the body that these cooling mechanisms cannot function properly. When it’s too humid outside, the body isn’t able to release sweat as efficiently and cooling slows. Prolonged sweating then decreases the body’s ability to radiate heat through vasodilation.

    The result is that the hypothalamus—the part of the brain that controls core temperature—becomes overwhelmed. The body produces more heat than it can release, and that’s when a person starts experiencing symptoms of heat exhaustion.

    Heat exhaustion symptoms include:

    • Profuse sweating
    • Nausea or vomiting
    • Headache
    • Paleness
    • Muscle cramps
    • Fatigue
    • Weakness
    • Dizziness
    • Fainting

    Mild cases of heat exhaustion can be treated at home, but severe cases require immediate medical attention.

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    How long does heat exhaustion last?

    So how long does heat exhaustion last? Because of the toll heat exhaustion takes on the body’s delicate cooling systems, it can take between 24 and 48 hours for a victim to recover from the stress.

    Depending on the severity of the heat exhaustion, it may take longer to recover—especially if the case requires hospitalization to replace lost body fluids.