Heat exhaustion and heat stroke are two heat-related conditions that, if left untreated, can have serious consequences.
Heat exhaustion
Heat exhaustion occurs when the core body temperature rises to between 37 and 40 degrees Celsius. At this point water and salt levels in the body begin to drop, causing symptoms such as nausea, sweating and feeling faint. If left untreated, it can progress to heat stroke.
Heat stroke
Heat stroke occurs when the core temperature rises above 40 degrees Celsius. Cells inside the body begin to break down, and important functions can stop working properly. Symptoms include mental confusion, hyperventilation and loss of consciousness. Heat stroke is a medical emergency. Without treatment it can cause multiple organ failure, brain damage and death.
Heat stroke is usually split into two categories:
- Classic heat stroke affects babies, the elderly and those with chronic health conditions, developing during unusually hot weather such as a heatwave.
- Exertional heat stroke affects young, active people during strenuous physical activity in the heat (athletes, military personnel, firefighters).
What to do
If someone with heat exhaustion is quickly taken to a cool place and given plenty of water to drink, the body should cool down and they should feel better within half an hour. If heat stroke develops, urgent medical treatment is required to bring the core temperature down. If treated quickly, around 90% of people with heat stroke survive.