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Heat exhaustion and sunstroke

Travelling in hot climates can make you sick, especially if you are not accustomed to the heat. Heat exhaustion and heatstroke are two related health conditions that can be very serious if not treated quickly. People at highest risk are the elderly, babies and young children, and people with chronic illnesses — even young and healthy people can get sick from heat if they participate in strenuous physical activities during hot weather.


Take these steps to prevent heat-related illnesses, injuries, and deaths when travelling in hot climates:

  • Drink plenty of fluids. Not all in one go – drink little, but often.
  • Wear loose, lightweight, light-coloured clothing including covering the head and neck and sunscreen.
  • Try to schedule outdoor activities during cooler parts of the day.
  • Rest often, and try to stay in the shade when outdoors.

If you will be doing strenuous activities in the heat, try to get adjusted before you leave by exercising one hour per day in the heat.

Heat exhaustion
Heat exhaustion is where a person experiences fatigue as a result of a decrease in blood pressure and blood volume. It's caused by a loss of body fluids and salts after being exposed to heat for a prolonged period of time [83]. Someone with heat exhaustion may have nausea and vomiting, feel dizzy or faint, fatigued, be confused, sweat heavily with a rapid heartbeat and very hot skin that feels ‘flushed’. 

Certain groups are more at risk of developing heatstroke or suffering complications from dehydration, and should be taken to hospital.
These include [83]

  • children under two years of age  
  • very elderly people 
  • people with kidney, heart or circulation problems 
  • people with diabetes who use insulin

Heat stroke / Sun stroke
Heatstroke is a more serious condition than heat exhaustion. It occurs when the body is no longer able to cool itself and the body's temperature becomes dangerously high due to excessive heat exposure [83]. Sun stroke is the most common type of heatstroke, where the source of heat is the sun. Sunstroke occurs when the sun shines on the head and parts of the neck for a long period of time.

Signs of heatstroke include: a temperature of 39°C or above [84], heavy sweating that suddenly stops, vertigo, confusion, headache, thirst, nausea, a rapid heartbeat, hyperventilation, muscle cramps and fits (seizures). Suspected heatstroke should always be regarded as a medical emergency as it can lead to life-threatening complications such as brain damage and organ failure.

What should I do if someone has signs of heat exhaustion, heat stroke or sun stroke?
If a person with heat exhaustion is quickly taken to a cool place and is given water to drink, and if excess clothing is removed, they should start to feel better within half an hour and have no long-term complications [83]. However, without treatment, they could develop heatstroke.

If you or anyone you are travelling with develops these symptoms, it is important to try to lower the body temperature. Get them to rest in a cool place, ideally a room with air conditioning, remove or loosen any unnecessary clothing and make sure that the person gets plenty of ventilation. Give them plenty of water to enable the body to lose heat by further sweating and avoid alcohol or caffeine as this can increase levels of dehydration. Cool the skin with cold water, using a shower or cold bath or if this is not possible, wet flannels applied to the head and body. Heatstroke is a life-threatening medical emergency and medical attention is required if symptoms persist.

Rehydration sachets 
Rehydration sachets help replace fluids and salts lost through heat exhaustion and sun exposure as well as diarrhoea and vomiting. You can buy sachets of rehydration salts from pharmacies in most countries of the world. They are added to water and when drank, they provide the correct balance of water, salt and sugar to enable optimal rehydration. It is not recommended to use homemade salt or sugar drinks as these may cause further dehydration if not balanced correctly. 

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