It’s that time of year when we stop complaining about the cold weather and start moaning that it’s too hot instead. We can usually manage to warm up in the winter with extra layers, turning up the heating a notch or two and having a cup of cocoa. Cooling down when it’s too hot on the other hand can be more difficult to manage. So when does ‘hot’ become ‘too hot’ and when is it time to start worrying? Here are our top tips for recognising and treating heat exhaustion and heat stroke.

Heat exhaustion

As we become too hot our bodies try to shed excess heat by opening up blood vessels and sweating (evaporative cooling) as well as breathing out warm air more rapidly. If the cooling responses are unable to keep pace with the overheating, we begin to show signs of heat related illness. Signs to be aware of include tiredness, headaches, nausea and vomiting and muscle cramps (caused by reduced salt levels through sweating). Somebody suffering from heat exhaustion should be conscious and alert.

The treatment for heat exhaustion is fairly common sense: cool down by stopping physical activity, getting into the shade and drinking water. If muscle cramps occur, don’t forget about topping up salts as well. This can be done with oral rehydration solutions such as dioralyte, or by eating salty food such as crisps after drinking fluids. Symptoms of heat exhaustion should usually improve within around 30 minutes of treatment.

Heat Stroke

There’s no clear dividing line between heat exhaustion and heat stroke, but a good definition of heat stroke is of life-threatening heat-related illness. The signs of heat exhaustion are usually present and heat stroke can present as a further deterioration from heat exhaustion.

Red flags to look out for are changing levels of consciousness (confusion, disorientation or loss of consciousness), seizures, a lack of sweating even when still hot and heat exhaustion that doesn’t appear to be getting better.
This is a medical emergency – treatment is to cool rapidly by stripping clothing off as far as possible, covering with wet clothing / sheets and fanning. An ambulance will be needed, even if the casualty appears to be improving. Water can still be given as sips if conscious.


Dehydration is related to both heat stroke and heat exhaustion. IT’s caused by a loss of fluids or a lack of fluids to replace those used up by the body. Excessive sweating without drinking enough can cause dehydration and, while it’s not strictly true that alcohol and caffeine are major causes of dehydration, they certainly don’t help to maintain fluid levels as effectively as water or isotonic sports drinks do. A significant cause of dehydration in a heat-exhausted casualty is vomiting if lost fluids are not replaced, so sips of water remain important, particularly if vomiting has taken place.

Prevention is better than cure

Sensible precautions, such as avoiding strenuous activity during very hot spells and staying in the shade during the hottest part of the day (usually 11-3) will help to avoid heat-related illness. Most at risk are young children and older adults. Young children’s brains are not fully developed, with the part of the brain that controls temperature less able to cope with extremes than an adult brain. Older adults are more likely to have underlying medical conditions and be on medication, both of which may make sweating less effective and reduce bloodflow.

Stay Safe in the Sun

Being aware of heat exhaustion and heat stroke is vital in the summer sun. Be prepared and look out for signs in those around you.