Sunstroke

Also results from overexposure to direct sun, usually afflicting those who are unaccustomed to host temperatures. Sunstroke (and other heatstroke's) are life endangering f not treated promptly, as the body's heat regulating mechanisms break down and allow the body to literally overheat.
Fast treatment consists of wrapping the patient, naked, in a cold, wet sheet. Douse the sheet continuously with extra water, or repeatedly sponge the victim with cold water. Force-feed the victim quiescently frozen confections. Continue until ht patients' internal temperature registers 101 degrees on a recta thermometer.