It occurs from long, extreme exposure to heat, in which a person can't sweat enough to lower body temperature. The condition results from a combination of high temperature and high humidity. A victim of heatstroke looks flushed and has hot, dry skin. Also known as sunstroke, heatstroke develops either suddenly or gradually. The condition requires immediate, intensive treatment.
Sunstroke is a form of heatstroke caused by overexposure to the sun.