How to prevent cold injuries

Cold injuries can be serious or life-threatening due to environmental exposure. They include hypothermia, chilblains, trench foot, frostnip, and frostbite. Generally, you can prevent cold injuries by wearing layers—and staying warm and dry—since getting wet can cause you to lose body heat faster.

Preventing cold injuries

While there are several different types of cold injuries, preventing them is generally the same. The goal is to stay warm and dry. If you get wet, you’ll lose body heat faster, leading to injury of the wet area, or whole-body hypothermia, which can be deadly. When you’re out in cool or cold environments, wear layers that include gloves and a face covering, especially if it’s windy. It’s better to have the layers with you and take them off if you feel hot than to travel a little lighter and get cold. In any environment, pack a couple extra pairs of clean socks if you’ll be out for more than a day. Trench foot can set in—in the heat or the cold—if your feet are wet. If it’s possible, take your boots off to let your feet air out and dry when you get some sleep. Be sure to change your socks too.

One of the best things you can do to prevent cold injury is to stay hydrated. If you’re out in the cold for hours or even days, the combination of heavy clothing and high-intensity activity that makes you sweat could lead to dehydration. This happens in cold weather for a number of reasons. Cold weather tends to move blood and other body fluids from your arms and legs to your core, increasing your urine output. Cold weather also decreases your body’s thirst sensation, which is normally an early sign of mild dehydration. Other signs of dehydration include headache, dry mouth, fatigue, muscle cramps, constipation, dry skin, and feeling dizzy or light-headed.

When you exercise in the cold, don’t rely on thirst to tell you when you need to drink. Be sure to drink often and before you’re thirsty. You should take in 3–6 quarts of fluid per day (including what’s in your food) during cold-weather training and operations. Also, take in enough electrolytes (minerals such as sodium and potassium) if you’ll be out for more than 2 hours. However, drinking too much plain water can cause hyponatremia (low sodium levels in your blood), which can result in severe brain damage or death.


Hypothermia happens when your core body temperature falls too far below normal. It’s usually classified as mild, moderate, severe, or profound. Mild hypothermia is when you start shivering aggressively and uncontrollably. People progressing to moderate hypothermia get what are called “the umbles”—they stumble, mumble, and grumble. Those are signs of decreased motor control (stumble), cognitive ability (mumble), and central nervous system function showing up as unusually bad mood (grumble). Severe and profound hypothermia happen when you lose consciousness and vital signs become difficult to detect.


Chilblains is a non-freezing cold injury because your body tissues don’t freeze. It’s the mildest of cold injuries and not life-threatening. Chilblains happens when your body is exposed to cold (not freezing) air temperatures, often when it’s windy and humid. It most commonly affects your fingers, toes, ears, and cheeks. When exposed to this type of cold, chilblains cause damage to the small blood vessels in the area, which will make your skin turn pale at first, but then get red and itchy. Unfortunately, this damage is permanent and the redness and itchiness will come back when the area is exposed to similar conditions again.

Trench foot

Trench foot is somewhat similar to chilblains. It’s a non-freezing cold injury where the damage is caused when the small blood vessels in the skin tissue on your feet close off. The difference is that it doesn’t need to be cold out to get trench foot, and it can happen even in desert environments. When your feet get wet and don’t dry, your body slows down the blood flow to your feet to keep them from losing heat. If they stay wet for too long, your skin starts to die as redness, tingling, and numbness set in. Over time, it can get itchy, and your skin will turn pale, then dark purple, gray, or blue.

Trench foot can get bad fairly quickly. Permanent tissue damage sets in after 6 hours without oxygen and can lead to foot amputation at 24 hours without oxygen. This is why trench foot was such a big issue in World War I and why Military Service Members are still encouraged to keep their feet clean and dry today.


Frostnip is when the outer layers of your skin start to freeze. The top layer of skin will look white and feel hard and rubbery. Frostnip is a mild cold injury that can be reversed as long as it’s treated before it progresses to frostbite. If you start to get frostnip, you can gently rewarm the affected area with a warm (105–110℉) water bath. Just let the area soak until the color returns to your skin. Once you’ve thawed out the area, it might start to hurt badly, which is normal. Finally, it’s very important that once the area is rewarmed, it needs to stay warm. Refreezing can cause more severe damage. If you won’t be able to keep the area warm, don’t start the rewarming process.

When you’re rewarming, there are a few things you should NOT do. Otherwise, you’ll risk causing damage to your skin and make the injury more severe.

  • Don’t use hot water. Always use warm.
  • Don’t run water over the area. Use a warm water bath and let it soak.
  • Don’t use dry heat. It is hard to maintain a warm temperature and can cause burns.
  • Don’t rub the area. It can cause damage to your skin while it’s thawing.


Frostbite is the more severe progression after frostnip. Its severity is usually classified into 4 levels: grades 1–4. Grade 1 is the mildest, where your skin can be swollen and itchy, but with no blisters. Grade 2 is when your skin starts to blister and peel. Grade 3 is where the skin starts to die, and it can turn black over time. Grade 4 is when deeper tissues and bone become severely damaged. Grade 4 frostbite also increases your risk of other infections that can be life-threatening if left untreated.

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Handford, C., Thomas, O., & Imray, C. H. E. (2017). Frostbite. Emergency Medicine Clinics of North America, 35(2), 281–299. doi:10.1016/j.emc.2016.12.006

Nagpal, B. M., & Sharma, R. (2004). Cold injuries: The chill within. Medical Journal Armed Forces India, 60(2), 165–171. doi:10.1016/s0377-1237(04)80111-4