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Disease Information Sheets

Heat Illness

Exposure to hot environments, or intense exercise in moderate environments or with inappropriate clothing, can cause several different illnesses that range from uncomfortable to life-threatening in severity. As a group, these illnesses are called heat-related illnesses or heat illness.


What illnesses are heat related?

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Are travellers and/or expat workers at risk?

Yes. All travellers and expat workers are at risk. People at even higher risk include anyone who is obese, unfit, unacclimatised, elderly, unwell, dehydrated from vomiting or diarrhoea, has underlying medical conditions such as heart disease or over-active thyroid, and those taking certain medications such as beta-blockers or diuretics.


How is it prevented?


The body adapts to heat exposure over a period of one to two weeks. The process is aided by 60 to 90 minutes of exercise per day in the heat. During acclimatisation the body adapts to produce more sweat at a lower temperature, which aids heat loss.



An acclimatised person can lose more than one litre of sweat per hour during exercise. Sweat contains both water and salts, so a balanced salt solution must be consumed in order to replenish those losses. Drink at least 500 ml of fluids at each break, plus 300-500 ml per hour. Signs of dehydration include thirst, production of small volumes of concentrated urine (or no urine produced), and in severe cases skin tenting (a pinch of skin does not spring back into place when released).



Wear loose-fitting, light coloured clothing. Consider periodically dipping it in water.



Rest is important, especially during acclimatisation, and particularly during the hottest part of the day.



A good level of physical fitness will improve the quality and rate of acclimatisation. Body fat is a good insulator - a leaner person loses heat more easily than a fatter person.

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