What is Heat Exhaustion?

Signs & Symptoms

• Heat rash (prickly heat) - occurs when the sweat ducts to the skin become blocked or swell, causing discomfort and itching.
• Heat cramps - occur in muscles after exercise because sweating causes the body to lose water, salt, and minerals (electrolytes).
• Heat edema (swelling) - can occur in the legs and / or hands when you sit or stand for a long time in a hot environment.
• Heat tetany (hyperventilation and heat stress) - usually caused by short periods of stress in a hot environment.
• Heat syncope (fainting) - occurs from low blood pressure when heat causes the blood vessels to expand (dilate) and body fluids move into the legs because of gravity.
• Heat exhaustion (heat prostration) - generally develops when a person is working or exercising in hot weather and does not drink enough liquids to replace those lost liquids.
• Heatstroke (sunstroke) - occurs when the body fails to regulate its own temperature and body temperature continues to rise, often to 40.6°C (105°F) or higher.

First-Aid for Heat Exhaustion

It's best to take measures to prevent heat exhaustion. Drink plenty of non-carbonated, non-caffeinated fluids and limit exposure to heat. Limit or avoid strenuous activity during hot or humid weather, particularly during the hottest part of the day between 11 a.m. and 3 p.m.

If signs of heat exhaustion appear, have the person stop their activity immediately, cool them down, and give them cold, non-caffeinated fluids to drink.

Preventing Heat Exhaustion

• Drink plenty of fluids, enough so that your urine is light yellow or clear like water.
• Drink plenty of water before, during, and after you are active. This is very important during physical activity in hot weather.
• During hot weather, wear light-coloured clothing that fits loosely and a hat with a brim to reflect the sun.
• Limit or avoid strenuous activity during hot or humid weather, especially during the hottest part of the day (11 a.m. to 3 p.m.). Heat exhaustion and heatstroke usually develop when you are working or exercising in hot weather. Humidity makes hot weather even more dangerous.
• Try to stay cool during hot weather. Stay indoors - visit public spaces that have air conditioning.

Adapted from:
Heat Exhaustion: Care Instructions. Government of Alberta.