Heatstroke’s aftershock: why cooling may not end the danger

Europe’s deadly heatwave is driving many heatstroke cases, where core body temperature above 40°C can cause brain dysfunction and multi-organ damage. Yet deaths can occur hours or days after cooling because the body’s immune system goes into a runaway, sepsis-like inflammatory state driven by neutrophils that damages blood vessels and triggers blood clots, overwhelming organs even once temperature is normalized. The current approach—rapid cooling—saves lives but doesn’t halt this immune cascade, so researchers are exploring strategies to calm neutrophil activity, prevent microthrombosis, and protect the gut barrier. Risk factors include age extremes, heart disease, diabetes, obesity, dehydration, alcohol, and certain medications. Faster cooling plus immune-targeted therapies could improve outcomes in heatstroke patients.