Sunstroke is a condition caused by your body overheating, usually as a result of prolonged exposure to or physical exertion in high temperatures. This most serious form of heat injury, sunstroke, can occur if your body temperature rises to 104 F (40 C) or higher. The condition is most common in the summer months.

Heat exhaustion is one part of the spectrum of heat-related illnesses that begin with heat cramps, progresses to heat exhaustion, and finally to heat stroke.

Heat exhaustion can progress to sunstroke when the body's temperature regulation fails. The person develops a change in mental status, becomes confused, lethargic, and may have a seizure, the skin stops sweating, This is a life-threatening condition and emergency medical attention is needed immediately.