"When summer temperatures start to rise, it's important to know how to prevent heat stroke. Look out for those who are vulnerable to heat stress or heat stroke, such as the elderly, the very young and the sick, because it's more difficult for them to maintain a normal body temperature. Avoid sun exposure on hot days, drink plenty of fluids, limit physical activity and stay in cool, well-ventilated areas."
Dr Christine Bennett, Chair, Medical Advisory Panel, Bupa Australia.
Heat stress occurs when your body is unable to cool itself enough to maintain a healthy temperature. Normally, the body cools itself by sweating, but sometimes sweating isn't enough and the body temperature keeps rising.
Over-exertion in hot weather, too long in the sun or bushfire exposure, and exercising or working in hot, poorly ventilated or confined areas can increase your risk of heat stress. Heat can also make an existing medical condition worse, for example heart disease.
Severe cases of heat stress can lead to heat stroke, which is a life-threatening medical emergency.
Generally, symptoms of heat stress include nausea, headaches and cramps, and a body temperature between 37 and 39°C.
Heat stroke is a more serious condition caused by a failure in your body's natural temperature regulation. Heat stroke has similar symptoms to heat stress but is more severe and the person may seem confused or aggressive, have a fit or lose consciousness. There may also be rapid pulse, headache, dizziness and dry, red skin. Body temperature will be over 40°C.
Heat stroke can cause the blood to thicken and organs to be damaged, which can rapidly lead to organ failure and death. It is a medical emergency.
Anyone can suffer from heat-related illness, but those most at risk are:
Elderly people are more prone to heat stress because their body may not adjust well to sudden temperature change. They are also more likely to have a chronic medical condition and be taking medication that may interfere with the body's ability to regulate temperature.
Heat waves kill more people than any other natural hazard experienced in Australia. In 2009, a two-week heat wave in South Australia and Victoria caused at least 150 deaths and may have contributed to more than 370 deaths. Between the years 1803 and 1992, at least 4287 people died in Australia as a direct result of heat waves. This is almost twice the number of fatalities attributed to either tropical cyclones or floods over much the same time frame.
There are many factors which can cause heat stress and heat-related illness, including:
Symptoms vary according to the type of heat-related illness. Babies and young children may show signs of restlessness or irritability and have fewer wet nappies. Older people may become lightheaded, confused, weak or faint.
Common symptoms include:
Heat stress is a serious condition that can develop into heat stroke. It occurs when excessive sweating in a hot environment reduces the blood volume. Warning signs may include:
Heat stroke is a medical emergency and requires urgent attention.
Heat stroke occurs when the core body temperature rises above 40.5°C and the body's internal systems start to shut down. Many organs in the body suffer tissue damage and the body temperature must be reduced quickly. Most people will have profound central nervous system changes such as hallucinations, coma and seizures.
As well as effects on the nervous system, there can be liver, kidney, muscle and heart damage. The symptoms may be similar to heat exhaustion but worse. The skin may feel dry and hot. There will be no signs of sweating. The person may stagger, appear confused, have a fit, or collapse and remain unconscious.
Treatment options vary according to the type of heat-related illness. Apply first aid and seek medical assistance immediately if you, or someone you are with, shows any sign of heat exhaustion or heat stroke. The first step for any heat-related illness is to move the person to a cooler, less humid environment. Other first aid measures are listed below.
Heat stroke is a medical emergency and requires urgent attention:
Prevention is the best way to manage heat-related illness. Some tips to prevent heat stress include:
Contact your doctor if you, or someone you know, appears to be suffering from a heat-related illness.
In an emergency, call triple zero (000) for an ambulance.
Sports Medicine Australia: Heat guidelines
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Last published: 30 July 2011
This information has been developed and reviewed for Bupa by health professionals. To the best of their knowledge it is current and based on reputable sources of medical research. It should be used as a guide only and should not be relied upon as a substitute for professional medical or other health professional advice.
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