Heat exhaustion and heatstroke are two heat-related health conditions. Both can be very serious.
Heat exhaustion
Heat exhaustion is when the temperature inside the body, known as the core temperature, rises to 37-40°C (98.6-104°F).
At that temperature, the levels of water and salt in the body begin to drop. This causes symptoms such as nausea, feeling faint and heavy sweating.
If left untreated, heat exhaustion can sometimes lead to heatstroke.
Heatstroke
Heatstroke happens when a person’s core temperature rises above 40°C (104°F). Cells inside the body begin to break down and important parts of the body stop working.
Symptoms of heatstroke can include mental confusion, hyperventilation (rapid shallow breathing) and loss of consciousness.
Heatstroke is a medical emergency. If left untreated, it can cause multiple organ failure, brain damage and death.
Types of heatstroke
There are two main types of heatstroke:
- classic heatstroke, and
- exertional heatstroke.
Classic heatstroke
Classic heatstroke usually affects the elderly, babies and people with chronic health conditions. It develops during unusually hot weather, such as a heatwave.
Exertional heatstroke
Exertional heatstroke usually affects young, active people doing strenuous physical activity for a long time in the heat. For example, cases of exertional heatstroke have occurred in:
- athletes,
- people serving in the military, and
- fire-fighters.
How common are heat exhaustion and heatstroke?
It is hard to tell exactly how common heat exhaustion is, as many people who get it do not go to their GP for treatment.
Heatstroke is rare in England, but during a heatwave the death rate among the elderly is much higher than usual.
Outlook
If a person with heat exhaustion is taken quickly to a cool place and given plenty of water to drink, they should begin to feel better within half an hour and experience no long-term complications. Without treatment, they could develop heatstroke.
Heatstroke is very serious and should be treated immediately. Treatment involves quickly cooling down the body to lower the core temperature.
If treated swiftly, 90% of people with heatstroke survive. If not, the survival rate is as low as 20% among vulnerable people such as the elderly.
