Heatstroke can cause long-term organ damage and obesity in mice, raising concerns about similar effects in humans. Researchers found that metabolic issues persisted for months, especially in males and those on high-fat diets.
Each year, over 100,000 people in the U.S. receive treatment for heat-related illnesses, a figure that has been increasing as global temperatures rise. The most severe form, heatstroke, can cause loss of consciousness, organ damage, and, in rare cases, death.
While many heatstroke patients appear to recover quickly, a new study from University of Florida researchers suggests otherwise. Their findings show that a single episode of heatstroke can cause long-term, multi-organ damage and lead to obesity in mice for months—equivalent to several years in a human lifespan.
“The animals appeared to recover over a few days, but their hearts metabolically crashed two weeks later, which is when physicians often stop following human patients,” said Thomas Clanton, Ph.D., a professor of applied physiology in kinesiology at UF who led the new study.
What’s more, mice fed a high-fat Western diet after recovering from heatstroke, which further stresses the body, packed on even more weight. Both male and female mice showed this chronic deterioration after heatstroke, but male mice suffered the worst effects.
The Importance of Prevention
The findings show how important it is to prevent and limit heat injury before it occurs, the authors say, by hydrating and cooling down when symptoms like fatigue set in. There is no established treatment for chronic heatstroke injury. But future research could help identify ways to limit the long-term damage in people.
With funding from the U.S. Army Medical Research and Development Command, Clanton’s lab developed their mouse model of heatstroke to help the military protect recruits and soldiers from the effects of heat injury. The Army’s improved procedures in recent years have greatly reduced the number of soldiers facing severe heatstroke.
But Clanton’s team noticed that some animals — and humans, too — seemed to experience lasting effects even after recovering from the initial injury, much like the chronic effects of concussions or viral infections that can last for years or even decades.
Heatstroke’s Impact on Heart and Metabolism
By following mice for three months after a single exposure to heatstroke, the researchers discovered that the heat injury weakened the animals’ hearts, made the animals eat more food and put on weight, and disrupted their metabolism of carbohydrates.
While the effects in mice may not translate directly to humans, Clanton and his colleagues are planning to follow people who have suffered heatstroke to further understand the factors that cause the long-term problems.
Their goal is to someday identify treatments that could help people recover more quickly, which could become even more important as the climate continues to heat up.
“We think there’ll be more of this chronic heat injury as we face a warming environment,” Clanton said.
Reference: “Mice develop obesity and lose myocardial metabolic flexibility months after exertional heat stroke” by Jamal M. Alzahrani, Ashley J. Smuder, Bryce J. Gambino, Cristina Delgado, Michael T. Rua, Ryan N. Montalvo, Finleigh P. Fitton, Deborah A. Morse and Thomas L. Clanton, 16 January 2025, Communications Biology.
DOI: 10.1038/s42003-025-07484-3
