Heat Exhaustion and Heat Stroke

Being exposed to high temperatures for long periods of time or engaging in vigorous activities in high temperatures can lead to heat exhaustion or heat stroke, especially if you are dehydrated or are taking certain medications such as antihistamines, blood pressure medication, or antidepressants.

Usually sweat evaporates from the skin to help cool the body. It is harder for sweat to evaporate if:

  • The humidity is high

  • You are wearing tight or layered clothing that covers most of your skin

  • You are dehydrated, which will cause you to produce less sweat

Heat Exhaustion

Heat exhaustion is a less serious condition than heat stroke. Symptoms can include:

  • Normal or only slightly elevated body temperature

  • Cool, moist (clammy), pale skin

  • Sweating (sometimes heavily)

  • Headache

  • Nausea/vomiting

  • Dizziness/weakness/fatigue

  • Rapid pulse

  • Decreased blood pressure

  • Dark urine

  • Muscle cramps

  • Rapid/shallow breathing

To respond to heat exhaustion:

  • Move into the shade or an air conditioned space.

  • Loosen clothing or remove as much clothing as possible.

  • Drink cool water or non-alcoholic, non-caffeinated beverages like sports drinks to help restore electrolyte balance.

  • Take a cool shower or sponge bath.

  • Spray cool water on yourself and sit in front of a fan or have others fan you.

  • Massage or stretch cramping muscles.

  • Monitor your temperature for changes in your condition that suggest heat stroke (see below).

  • Seek emergency treatment or call 911 if attempts to decrease body temperature fail or if you experience chest pain, abdominal pain, persistent vomiting so that you can't keep down fluids, or if you develop any of the symptoms of heat stroke (see below).

Heat Stroke

Heat stroke is an emergency situation in which the body loses its ability to cool itself. The internal body temperature rises to extremes, sometimes as high as 106 degrees F. Heat stroke can result in death if not treated promptly. Symptoms include:

  • Very high body temperature, usually over 104 degrees F

  • No sweating

  • Hot, dry, red skin

  • Rapid pulse

  • Difficulty breathing

If body temperatures aren't reduced, symptoms can progress to:

  • Confusion, irritability, disorientation, or hallucinations

  • Seizures

  • Loss of consciousness and coma

  • Death

To respond to heat stroke, CALL 911 or go to the closest emergency room. While waiting for EMS:

  • Move the person into the shade or into air conditioning.

  • Elevate their feet higher than their head to reduce the chance of shock.

  • Remove clothing and attempt to cool them down by wrapping them in a cool, wet sheet or spraying them with cool water and fanning them.

  • Put ice packs or cold compresses under their arms, on their groin area, and behind their neck.

  • Give them cool drinks only if tthey are not disoriented and not vomiting.

  • Stay with them until EMS arrives.

Preventing Heat Exhaustion and Heat Stroke

Stay hydrated by drinking lots of non-alcoholic, non-caffeinated beverages, even if you're not thirsty. Water is good, but sports drinks are better if you are engaging in vigorous activity in high temperatures.

  • Drink enough to keep your urine very pale yellow. If it's a dark yellow, or if you are going for long periods of time without urinating, you're dehydrated. (Some medications and supplements can turn urine bright yellow or orange. If in doubt, ask a pharmacist or your healthcare provider about the medications and supplements you use.)

  • Don't stay outside in high temperatures for long periods of time. Take breaks indoors.

  • Don't engage in vigorous activity in the hottest part of the day - from 11am - 5pm.

  • Wear loose, lightweight clothing made of fabric that breathes and allows your sweat to evaporate.

  • If you start to feel very hot or have any of the symptoms of heat exhaustion, respond immediately as described above under "heat exhaustion."

Courtesy of University Health Services, The University of Texas at Austin.
Published by the University of Texas at Austin University Health Services.
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
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