What Happens during Heat Stroke and How to Prevent It


Young kids are at increased risk of heat stroke. Credit: IStock

Temperatures in July and August 2016 were the hottest ever recorded on the planet and much of the U.S. is still struggling with a heat wave. Hundreds of heat-related deaths occur in the U.S. each year, and these rates are on the rise. Awareness of when the body is losing the ability to deal with heat and seeking treatment for heat illness and dehydration are key to reducing heat stroke-related deaths. So it’s extremely important to understand the causes and symptoms of heat illnesses, such as heat stroke, and who’s at risk.

Under normal physiologic conditions, the human body can counteract overheating by sweating and other means. Heat illness occurs when the body is overwhelmed by the heat and can no longer maintain its temperature. Heat stroke is the most dangerous type of heat illness, though heat fatigue, heat cramps and heat exhaustion can also occur. These conditions can have a variety of effects on the body, blood flow and a person’s mental capacity. For example, heat stress with mild to moderate dehydration can result in loss of blood flow to the brain and the inability to stay upright.

Who’s at Risk of Heat Stroke and How to Prevent It

Heat stroke can develop in people of any age or health status, but the sedentary elderly, very young people and individuals with chronic disease such as heart disease have a significantly higher risk of having one. People who take certain medications, drink alcohol, are very overweight or who have poor blood circulation (such as those with diabetes and heart disease) or reduced sweat production due to aging are also at an increased risk. Prolonged, intense exercise in a hot environment without proper hydration can cause a heat stroke during heat waves, even among young and healthy people.

The most effective ways to prevent heat stroke is to ensure that high-risk populations:

  • have access to air conditioning or a cool environment with air flow;
  • dress comfortably in layers that can be removed as the temperature rises;
  • stay hydrated by consuming water, fruits and vegetables (such as watermelon, tomatoes, lettuce, pineapple, cranberries and oranges), herbal tea, etc; and
  • understand the signs and symptoms of heat stroke.

People may be developing heat illness if they appear confused or faint, are not sweating or have flushed skin after being exposed to the heat. Any individual experiencing these symptoms should be removed from the heat, offered fluids and examined for the possibility of heat illness or heat stroke.


Robert Carter, III, PhD, MPH, FACSM, is an adjunct professor of emergency medicine at the University of Texas Health Science Center at San Antonio and the product manager for medical simulation at the Program Executive Office for Simulation, Training and Instrumentation in Orlando.

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