Hypothermia – Prevention, Symptoms & Treatment

Hypothermia is subnormal body temperature that occurs when the body loses heat faster than it can produce it. It is most often caused by exposure to cold temperatures. Other factors that may contribute to the onset of hypothermia include over-exertion, inadequate food and fluid intake, immobility and lack of shelter. While usually associated with below freezing temperatures, it is worth noting that hypothermia can occur any time that cool (not necessarily cold), wet and windy conditions are prevalent.


Shimshal Pamir

When temperatures drop quickly, add layers and/or keep moving in order to maintain body heat and prevent a slowing down of blood flow | Shimshal Pamir | Karakoram Range, Pakistan, 2008

Cold-related maladies such as hypothermia and frostbite are far easier to prevent than they are to cure. Here are seven proactive measures that hikers can take in order to avoid hypothermia:

1.  ForecastAlways check the forecast before setting out. Adapting is a lot easier if you know what’s coming.

2.  Awareness: Watch the weather (forecasts can sometimes by wrong) and know your limitations. If conditions are deteriorating and you’re feeling exhausted, don’t hesitate to set up your shelter and call it a day.

3.  Appropriate clothing / Pay Attention to the Extremities: Use layering principles. Pay particular attention to the extremities. Your head, hands and feet constitute the body’s initial warning system in cold conditions.

4.  Minimize sweating: Over-dressing and over-exerting can lead to excessive perspiration, which in turn can result in a lowering of body temperature. Constantly monitor yourself and remove or add layers accordingly. Make sweating as little as possible a priority in cold conditions.

5.  Short breaks: The longer you stop the colder you become. When the weather turns nasty, keep breaks short and to a minimum. If you are taking a longer break, put on an extra layer or two.

6.  Food: During the day eat high-energy snacks at regular intervals. Before going to bed, your evening meal should emphasize fats and proteins, which are processed slower by your digestive system, thereby keeping you warmer during the night.

7.  Hydration: When conditions are cold and the sun is no where to be seen, hikers often forget to drink enough water. This is a mistake. If you are dehydrated you are more susceptible to hypothermia (see Hydration for details).


Not a great time for a break | Whiteout conditions on the summit of Mt.Moosilauke | November, 2012 | Appalachian Trail | White Mountains, NH, USA

Symptoms & Treatment

The onset of hypothermia is typically gradual and the victim is often unaware that they require emergency medical treatment. Physical and mental capabilities are progressively diminished, therefore the key to successfully treating hypothermia is early recognition.

If you are hiking in a group, be alert to any changes in the demeanour of your trekking mates. If you are hiking solo, you need to be even more vigilant in regards to monitoring your own physical and mental state. If you notice changes, take preventative measures sooner rather than later.


Symptoms of mild to moderate hypothermia include:

  • Shivering
  • Slurred speech
  • Loss of balance and coordination
  • Loss of dexterity in the fingers
  • Slowing in the response mechanism

Severe cases of hypothermia (i.e. when body temperature drops below 28C / 82F) exhibit the following additional symptoms:

  • Shallow or no breathing.
  • Weak or irregular pulse.
  • Dilated pupils
  • Muscle rigidity
  • Increasingly pale skin colour.
  • Progressive loss of consciousness


In treating hypothermia the objective is to prevent further heat loss and slowly rewarm the patient. Note that severe hypothermia is a potentially fatal medical condition. In such cases, every possible effort should be made to contact an emergency response team. To treat someone with hypothermia take the following steps:

  • Find or set up shelter.
  • Remove wet clothing.
  • Put on something warm and dry.
  • Get into sleeping bag. Be sure to lay out a sleeping mat first in order to insure sufficient insulation from the ground.
  • Eat high-energy snacks such as chocolate.
  • Drink warm fluids. Avoid coffee and alcohol which dehydrate and accelerate heat loss.
  • If you are shivering and happen to be hiking in a group, share your sleeping bag with someone who is warm and dry.
  • Focus on rewarming the centre of the body – groin, stomach, chest, neck and head. Warm (not hot) compresses are ideal. DO NOT attempt to rewarm the limbs as this will push cold blood back towards the lungs, heart and brain.
  • It is common for people suffering from severe hypothermia to also have frostbite. DO NOT rub frostbitten areas, as this can severely damage the affected tissues.
  • If the victim’s breathing has either stopped or appears threateningly slow or weak, begin CPR immediately.

For an excellent online overview of hypothermia and other cold weather maladies, see Princeton University’s Outdoor Action Website.



Hypothermia – Prevention, Symptoms & Treatment — 7 Comments

  1. Happened to me. Last Spring in VT. Right in an area i have hiked numerous times. Summer gear. Chilly drizzle. In the 40’s My mind just would not tell me what to do. I KNOW WHAT TO DO. Finally my wife got me to get in my bag in the William B. Douglas shelter. Shivered and drank hot tea and slept and warmed up. I was fine in the morning.

    Thing is I’ve hiked in cold and wet in the same gear many, many times.

  2. happened to me in a November, hunting in a ground blind, air temp was 40 something shivering almost like convulsions, had that slurred speech, slow muscles, uncoordinated, Then in February just car camped, at night it was in the teens, I was all layered up with clothes, real good, sat up in front of the fire till way past midnight, was fine, went to bed in the tent, took a lot of layers off, slept in my long johns slept like a baby, didn’t wake p till past 9 am. The point is, yes the temperature doesn’t have to be extreme

    • “Well above freezing” is pretty broad.

      However, hypothermia can definitely be an issue in cool/cold, wet and windy conditions (e.g. South West Tasmania, Scottish Highlands, South Island NZ, Tierra del Fuego).

  3. I’ve had Hypothermia 3 times, all on or near the AT. The first 2 it did not get below 40 degrees, all 3 times I was hiking in the rain.
    First a bit about me: I have been an EMT & Paramedic for 25+ years when I got my first bout, I am well trained in spotting Hypothermia.
    Episode #1:I hiked out of the NOC, during the day I hate about 400 to 500 calories, including dinner. Slept well at Locust Cove Gap, I think I skipped breakfast, 30 minutes into my hike, it started to rain & I had crappy rain gear. Long & short of it: I got to Brown Fork Gap EXHAUSTED! Walked in to the shelter & realized I may be in trouble, a fellow hiker (we hat camped near each other last night) said “You look like S**t” I got my sleeping bag out, got in it & fixed dinner,,, it was 11 AM. I almost immediately felt better, that is when I realized my problem was Hypothermia. Before warming up & eating, I could not see it. Stayed put & hiked to GSMNP next day after eating 3 dinners & a bunch of snacks.
    Episode #2: OK, I told me, You have had Hypothermia before, should be easy to spot now. Right? WRONG! Hiked out of Hot springs (a few years later) Again, above 40 & raining. I kept going, but wasn’t feeling it, made it to the camp just after the Rich Mt fire tower, stopped to talk to some Thrus camped there, was going to press on, “After all I only have just over 2 miles to go” but the group slowly surrounded me, I barely noticed actually, the “Leader” kept me focused & told me I was going to camp her tonight. I (think) said no, but he was insistant. Then he asked if I had a tent, “Yes” “Can you set it up?” Then, Like I was hit with a big stick “OH! I am in BIG trouble!!” so I just shook my head no. ‘Can you get it out?” so I did “Can you tell us how to set it up? I shook my head yes, had to mostly point as by now talking was a huge effort. They got it set up & Me in it & in my sleeping bag. No memory of if I put on dry clothing. 5 minutes later, although it could have been hours, I was able to fix dinner.
    The next morning, I saw where I would have gone down, don’t know how I knew this, but I saw it clear as can be. My previous episode & all my training did nothing to alert me to my problem.
    Episode 3: Yea, above 40 & raining. At least this time I had companions, but the temps dropped, rapidly to below freezing at ground level, but the rain continued to fall (Tip: Goretex stops working when covered in 1/4” of ice) We made it to the Wise shelter & by group vote, decided we 4 were in trouble. We had friends less than 2 miles away, & evacuated to them & their warm cars. Plan B was to hammock in the shelter with my tarp over the opening, either way, we had options. This time, the only reason I knew I was in trouble with Hypothermia, I could see my companions were. I felt “Fine” wife says it took me 2 weeks to get back to normal, I was talking like I had a brain injury.
    What saved me (US”) was I had a plan AND a back up plan already in place BEFORE we got in trouble, cause trust me, you will NOT be able to come up with one after the Hypothermia sets it, IF you even notice.
    Stay safe out there, were all in this together.

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