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Hypothermia – Causes, treatment and avoidance

Waterproof clothes
Normally your body temperature lies between 36.5 and 37.5C. If it begins to drop below this you will feel cold, you might start to shiver, rub your hands together or look in your pack for a fleece.
If it drops below 35C you will start to shiver, your mood may change, your lips may go blue, you may become clumsy and irrational.

You have hypothermia

At this stage there is plenty you, or your buddies, can do to reverse the cooling process, and you need to act immediately to prevent the situation worsening. But how did you get to this point in the first place?


Hypothermia occurs when the body temperature falls below 35C, and has several causal factors:
A cold air temperature in itself will not generally cause hypothermia, but it is a considerable contributor when combined with the other factors below.
Water will reduce the insulating properties of your clothing, and as it evaporates from your clothes and skin it takes a lot of heat away from the body.
Wind will remove the warm air layer next to your skin, and increases evaporation of water from wet clothing, which in turn increases the cooling effect.
Your body heat is maintained by metabolising fuel into energy. If you are low on fuel reserves your body will be unable to ‘make’ sufficient heat to maintain your body temperature.

Signs and Symptoms

The symptoms of mild hypothermia are all to common, you may have come across someone displaying these yourself. They will be shivering, possibly be incoherent, will have bluish lips and pale, cold skin. They will have the ‘umbles’ (stumble, mumble and grumble). They may be irrational and may deny they have a problem.
If the body temperature falls towards 33C then moderate hypothermia symptoms appear. The victim will show uncontrollable shivering and cannot stop if you ask them to, they will be confused and will have heightened signs of the ‘umbles’. They may try to remove layers of clothing in their confusion. Their heart and respiratory rate will increase.
Around 32C they will become stiffer in the limbs, the shivering will stop, they may become semi-conscious or unconscious and collapse. Heart rate will be harder or impossible to detect as blood is drawn away from the limbs and into the core of the body in an attempt to keep the vital organs functioning. This is severe hypothermia.
Cardiac arrest occurs at around 28C.


Treatment for all levels of hypothermia is to attempt to rewarm the victim.
In the case of mild hypothermia you should seek shelter from the weather, either a tent or bothy bag would suffice. If possible remove wet clothing and replace with dry, and add insulation layers, jacket, fleece, hats and gloves will all help. Give food in the form of a sugary snack, and a hot drink, (but avoid alcohol, and caffeine if possible).
Get them active, slapping their body with their arms for example. Give them plenty of encouragement and get them to walk when they are ready, but keep them supervised.
Remember to check other members of your group, if one person is suffering from hypothermia then it is likely that others may be too.
For cases of moderate hypothermia you should again seek shelter and insulate the body of the victim. Handle them gently, to avoid sending cold blood to the vital organs in the core of the body and do not rub the extremities, such as hands, to try to warm them. Give them sugary foods and a warm drink, but only if they are able to swallow.
Immediate recovery is unlikely, so call out Mountain Rescue to evacuate the casualty.
If the victim is losing consciousness, and showing signs of severe hypothermia, then find shelter as above, insulate and put into the safe airway position. Handle with great care and do not try to feed or put drink into their mouths. Call out Mountain Rescue immediately.
A casualty is never ‘cold and dead’, they are only ever ‘warm and dead’ after rewarming in the hospital.


Clearly, it is better to avoid the above scenarios occurring at all, so ensure you and your group have sufficient warm clothing for the weather you expect to encounter, hats, gloves, (and a spare pair), and extra insulation should be carried. Make sure your footwear is waterproof, and take gaiters if wet conditions are expected.
Take sufficient energy producing food to last you the day, and a hot drink, (try to avoid caffeine).
It is vitally important to always carry effective waterproof clothing, including leggings.
Plan your route to take into account the weather forecast and the conditions you expect to encounter.
Finally, remember that hypothermia can occur at any time of year, not just in the winter months, so be prepared.