Heatstroke tricks the body into launching the kind of all-out inflammatory attack it normally saves for life-threatening infections. Except there is no infection: the immune response is activated with no clear target, and it stays hyperactive long after the body has cooled. When your body overheats, it pulls blood away from the organs and pushes it toward the skin, trying to dump heat. The enzymes they release during heatstroke can trigger the formation of tiny clots in capillaries (tiny blood vessels) throughout the body. Older adults and babies struggle to regulate body temperature.