Can Heat Be Dangerous? Definitely. It Can Kill

Hot, muggy summer days are great for spending time in a pool but not so great for other athletic or physical activities. As the temperature and humidity rise, you’ll want to pay attention to the potential for heat-related illnesses.

When the body is unable to cool itself by sweating, heat illness can occur.

Factors that can lead to heat illness are:

  • High temperature
  • High humidity
  • Direct sun
  • Limited air movement
  • Physical exertion
  • Poor physical conditioning
  • Certain medications
  • Inadequate tolerance for hot environments.


People that are most at risk for heat illness include:

  • Infants and young children
  • Adults over age 65
  • Those with mental illness
  • Those with physical illness. (i.e. high blood pressure or heart disease)


Heat illness is gauged by three levels of severity.


Heat cramps

Heat cramps are painful, involuntary muscle spasms that usually occur during heavy exercise in hot environments. You may be prone to this type of muscle cramp if you don’t get enough fluids or you have an imbalance between water and electrolytes.

Signs and symptoms:

  • Profuse sweating
  • Muscle cramps — most often occurring in calves, arms, abdominal muscles or back


  • Replace fluids; drink water, clear juice or sports drink
  • Stretch and gently massage affected muscle group
  • Apply ice
  • Stop or reduce activities for the rest of the day; otherwise there’s a good chance cramps could return


  • Eat a diet rich in potassium and calcium
  • Replace your fluids after workouts. Include a solution of electrolytes (potassium, sodium and calcium); complex carbohydrates may also be helpful
  • Drink before you’re thirsty; schedule water breaks at regular intervals throughout the exercise or work session to help maintain your hydration levels


Heat Exhaustion

Heat exhaustion results from dehydration. Signs and symptoms often begin suddenly and resemble the signs and symptoms of shock.

Signs and symptoms:

  • Flushed skin, profuse sweating
  • Weakness and moist skin
  • Mildly elevated body temperature
  • Dizziness, headache
  • Lightheadedness or fainting
  • Upset stomach, vomiting
  • Mood changes that may include irritability or confusion
  • Dark colored urine
  • Rapid pulse and breathing rate


  • Remove the person from the sun/hot environment; place in cool or air conditioned place
  • Replace fluids
  • Remove excess clothing
  • Place cool compress directly on body
  • Lay the person down, elevate legs and feet slightly
  • Monitor person closely; heat exhaustion can quickly become heatstroke!


  • Replace fluids consistently before, during and after physical activities
  • Eat a balanced diet
  • Wear light-colored, loose-fitting, moisture-wicking clothes
  • Avoid drinks that contain caffeine, large amounts of sugar, or alcohol as they cause additional fluid loss


Heat Stroke

Heat stroke is the most severe heat-related illness. Heat stroke can be fatal. It results in the body’s inability to regulate body temperature by sweating.

The main sign of heat stroke is a noticeable, elevated body temperature (i.e. generally greater than 104˚F) with changes in mental status ranging from confusion to coma.

Heat stroke is a medical emergency. Call 911.

Signs and symptoms:

  • Headache, dizziness
  • Unconsciousness
  • Red, hot, dry skin with no sweating
  • Mental confusion
  • Rapid pulse rate
  • Loss of consciousness
  • Seizure/convulsions
  • Very high body temperature


  • Move person to cool, well ventilated location
  • Immerse the person’s full body in cold water if available
  • Remove as much clothing as possible
  • Monitor vital signs
  • Call 911 to activate Emergency Medical Services (EMS)

The goal of treatment for these heat-related illnesses is to reduce body temperatures and replace fluids. It’s important to monitor body temperature, heart rate and respiration rate. If any changes occur, or there is any doubt to the severity of the heat illness, call 911 to contact Emergency Medical Services.

Prevention is the best defense against heat illness. On hot and humid days, workouts and strenuous outdoor activities should be scheduled for the early morning or evening hours, when the temperature is not as high.

Wearing light-colored, loose fitting clothing, a hat, sunglasses and using sunscreen is advised.

During physical activity, we recommend that participants drink one cup of water every 15-20 minutes. Additionally, avoiding drinks that contain caffeine, high sugar content and/or alcohol is a key to proper hydration.

Finally, familiarity with the Heat Index is an important step for avoiding potentially dangerous exposures to hot environments. The Heat Index is the temperature the body feels when heat and humidity are combined.

As a general guide, use the following temperature and humidity levels to identify potential heat problems:

  • 80-90˚F, with 70-90% humidity — Fatigue is possible when combined with prolonged exposure and physical activity.
  • 90-105˚F, with 50-90% humidity — Heat cramps, heat exhaustion and heat stroke is possible.
  • 105-130˚F, with 40% humidity — Heat cramps, heat exhaustion and increased likelihood of heat stroke.
  • 130˚F or greater, with 40% humidity — Heat stroke likely with continued exposure.

Heat illness can be extremely serious, even leading to death.

If you have additional questions about heat-related illnesses, other sports medicine topics or to schedule a Free Injury Evaluation, call the Aurora Sports Medicine Hotline™ at 414-219-7776 or 800-219-7776.

Meet the Author

Marissa Strehlow, MS, LAT, is an athletic trainer at Aurora Sports Health in Mequon and is the athletic trainer for Nicolet High School.

Read more posts from this author

The information presented in this site is intended for general information and educational purposes. It is not intended to replace the advice of your own physician. Contact your physician if you believe you have a health problem.

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