• Posted August 27, 2026

Heat Waves Linked To Dozens Of Health Problems, Emergencies

Health problems caused by heat waves extend far beyond simple dehydration or heatstroke, a new study says.

As many as 33 diagnoses can be tied to extreme heat events, researchers reported recently in the journal Science Advances.

The medical problems include rashes, kidney failure, multiple sclerosis, mental disorders, insect bites, traffic accidents, injuries from violence and gunshot wounds, researchers found.

“Previous research has shown that when people are exposed to extreme heat, they often act more aggressively, so that may be playing a factor here,” said researcher Daniel Horton, an associate professor of Earth, environmental and planetary sciences at Northwestern University in Chicago. 

“When it’s hot out, your body is stressed, and your mind is stressed, so that may be distracting or aggravating, and it could lead to more accidents,” Horton said in a news release.

Climate change is expected to lead to more heat waves, researchers said in background notes.

To evaluate how heat waves might affect human health, researchers examined more than 1,800 diagnoses across nearly 1 million ER and urgent care visits in Chicago. The visits occurred between 2011 and 2023, from May to September. 

Results linked 33 specific diagnoses with exposure to extreme heat.

“It is a public health obligation to protect the individuals and communities most vulnerable to the harmful effects of climate change,” lead researcher Hyojung Jang said in a news release. She is a doctoral candidate in biostatistics at Northwestern University Feinberg School of Medicine in Chicago. 

“If we’re only tracking the more commonly known heat-related illnesses, we’ll underestimate the true heat-related health burden, which could result in vulnerable people and communities being overlooked,” Jang said.

Cities can prepare for heat waves and protect citizens by providing air-conditioned spaces, planting more trees, installing more shade at bus stops, and requiring landlords to provide adequate cooling in apartments, researchers said.

“Since we know there’s an association between extreme heat and a number of different health outcomes, reducing exposure is critical,” Horton said.

More information

The Harvard T.H. Chan School of Public Health has more on heat waves and health.

SOURCE: Northwestern University, news release, Aug. 26, 2026