What is Frostbite

What is Frostbite?It’s the condition that haunts all outdoorsmen and women as soon as the temperature starts to drop. Fingers go numb, toes start to tingle, and the thought creeps slowly into the back of your mind: Frostbite.

Frostbite, “congelatio” in medical terminology, is defined as injury to body tissues caused by exposure to extreme cold, that can result in reduced circulation in local extremities and in extreme circumstances gangrene. It occurs when intense cold causes ice crystals to form under the skin and the underlying blood vessels. These crystals cause blood to clot in the blood vessels, thus reducing the oxygen supply to essential tissues. Frostbite is usually preceded by a feeling of numbness called frostnip.

Here are some ways you can identify frostbite and its severity.

Signs and Symptoms

Through the long evolutionary process, our bodies have come to know that for survival, it’s more important that we’re able to pump blood and take in oxygen than it is to, say, grasp something with our fingers or run on two feet. Therefore, when external temperatures go down and the body core temperature begins to cool, the body will concentrate warmth around the core where all the organs are. The body begins to go into “protect the important stuff“, mode. When the temperature drops to around the freezing point (or the wind makes it feel around the same temperature) the blood vessels in your extremities start to constrict. This keeps blood warmer and forces the blood to flow closer to core organs, like the lungs and heart.

This lack of blood will eventually turn your fingers and toes into martyrs of the heart. As the amount of blood circulating in these areas decrease, so does the heat provided to them. If this process continues, eventually the tissue will begin to freeze. This is bad news. As the skin freezes, irreversible damage can be done to the tissue.

Frostbite can be categorized into three different stages of severity:

First degree

As mentioned previously, the first stage of frostbite is called frostnip. Frostnip is characterized by a feeling of numbness and discoloration of the skin. It can also sometimes include a painful itching Frostbitten Toessensation. When identifying frostnip, look for white, red, or yellow patches of skin, and check for numbness. Most people who get frostnip do not suffer from permanent damage to the skin. Occasionally, people do experience long-term desensitization to both warm and cool temperatures, on the affected skin.

Second degree

As things degenerate, the little ice crystals that formed only on the surface of the skin will start to spread into the underlying tissue. If the freezing continues to the inner skin, but stops before it reaches deep tissue, it is called second degree frostbite. Second degree frostbite usually results in some pretty ugly black and purple blisters, as the affected areas heal. Fortunately, second degree frostbite can heal normally, as well. Typically it takes one to two months for second degree frostbite to heal completely. However, there is an increased risk of the sufferer not being able to feel changes in temperature, in the affected area.

Third and fourth degrees

If you happen to be reading this for an on-the-fly attempt at diagnosing, we recommend that you seek professional medical help now.

Once the freezing has reached deep tissue, true frostbite has set in. Everything from skin, to muscles, to nerves has frozen solid and isn’t working. As expected, the skin is hard. Use of the affected appendage has been temporarily lost and may not come back. A few days after the frostbite, the area will swell into large purple or black, blood-filled blisters. If untreated, severe frostbite may give way to gangrene and may require amputation of the affected area. The long-term effects of severe frostbite are hard to determine at first. Usually, damaged tissue must be removed, and damage to nerves and inner tissue must be assessed. Sometimes the long-term effects are not known for months. It is important to have any degree of frostbite treated by a medical professional, as soon as possible.

Now that you know the symptoms and signs of frostbite, it’s also important to remember that it’s not only the bad weather that effects you; the type of outdoor gear you have plays a big role as well. So be safe and prepare accordingly for when you’re going out to face the cold!

Photo Credit: DG Jones via Photopin per CC
Photo Credit: mikep via Photopin per CC


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  • Inside Out Fun

    Very helpful information. It’s easy to overlook the early signs of frostbite when you’re outside sledding or tubing.

  • Mike

    Pretty worthless, shallow post about frostbite. If you are interested in knowing about frostbite, get your hands on the info distributed on the Alaskan Pipeline almost 40 years ago. If your feet freeze and you have to walk, don’t thaw and walk on them. Walk on them frozen. When you thaw the injury, do it rapidly in 100-104 degree F water. Then you need for the tissue to recover for weeks without use.

  • MikeinFairfax

    Spent four years with the Army in Alaska, where we were trained to handle fuel with extreme caution in sub-zero temperatures. Gasoline spills at minus 40 can instantly freeze a hand deep into the tissue, so fuel handlers normally wore heavy rubber gloves. Most winter campers do not have to work with fuel hoses and jerry cans, but even Coleman fuel or alcohol splashed onto a hand or face in those frigid conditions can cause severe frostbite injuries. Latex gloves under leather gloves are a good precaution when filling a camp stove in extreme temperatures.