Frostbite and Immersion (Trench) Foot

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Exposure to cold may lead to injuries such as Frostbite and Immersion (Trench) Foot. The focus of survival medical training should be general, but also take into account the type of environment that you expect to live in if a disaster occurs.   If you live in Miami, it’s unlikely you’ll be treating a lot of people with hypothermia.  If you live in Siberia, it’s unlikely you’ll be treating a lot of people with heat stroke. Learn how to treat the likely medical issues for the area and situation that you expect to find yourself in.

One major environmental risk is the effect of ambient temperature. Humans tolerate a very narrow range and are susceptible to damage as a result of being too cold or too hot.  Your body has various methods it uses to control its internal “core” temperature, either raising it or lowering it to appropriate levels.  The body “core“ refers to the major internal organ systems that are necessary to maintain life, such as your brain, heart, liver, and others.  The remainder (your skin, muscles and extremities) is referred to as the “periphery”.

It’s been a harsh winter, with storms buffeting the Midwest and Northeast in the last few weeks.  Reading about deaths than occurred due to lack of preparedness, we wrote an article recently on general hypothermia.  To read the article, click here:

In general hypothermia, the body’s core temperature drops below 95 degrees F.  There are cold-related injuries that occur in the periphery, however, and you might just encounter them if you’re on a winter hike or if there is a disaster-related grid shutdown.

Two particularly difficult ones to deal with are Frostbite and Immersion (trench) Foot. Frostbite is the freezing of body tissues, and it usually occurs in the extremities, especially fingers and toes. Sometimes, the ears, nose, and even the lips may be affected.

These conditions usually occur as a result of inadequately preparing for a trip in cold weather.  If you expect to be outside for extended periods of time, dress warmly and consider what you would do for shelter and heat if you found yourself stranded somewhere.   You could easily get lost during a hike in a snowstorm, have your car stall out, or other mishaps, so don’t feel that it couldn’t happen to you.

Although I’ve mentioned this before, It may be useful to remember the simple acronym C.O.L.D. This stands for:  Cover, Overexertion, Layering, and Dry:

  • Cover. Protect your head by wearing a hat. This will prevent body heat from escaping from your head. Instead of using gloves to cover your hands, use mittens. Mittens are more helpful than gloves because they keep your fingers in contact with one another.  This conserves heat.
  • Overexertion. Avoid activities that cause you to sweat a lot.  Cold weather causes you to lose body heat quickly, and wet, sweaty clothing accelerates the process. Rest when necessary; use rest periods to self-assess for cold-related changes. Pay careful attention to the status of your elderly or juvenile group members.
  • Layering. Loose-fitting, lightweight clothing in layers insulate you well. Use clothing made of tightly woven, water-repellent material for protection against the wind. Wool or silk inner layers hold body heat better than cotton does. Some synthetic materials work well, also. Especially cover the head, neck, hands and feet.
  • Dry. Keep as dry as you can. Get out of wet clothing as soon as possible. It’s very easy for snow to get into gloves and boots, so pay particular attention to your hands and feet.


Frostbite is sometimes listed in stages, from minor “frostnip” to severe cases causing permanent loss of tissue. Initial symptoms of frostbite include a “pins and needles” sensation and numbness. Skin color changes from red to white to blue as the condition worsens.  The skin will begin to harden and may feel “waxy” to the touch. If cold exposure continues, the color may change to black, indicating that a condition known as “gangrene” has set in.  Gangrene is the death of tissue resulting from loss of circulation.  This usually results in the loss of the body part affected.  Infection may also set in, affecting the entire body.  This is called “Sepsis” and is life-threatening.

Immersion foot causes damage to nerves and small blood vessels due to prolonged immersion in cold water.  This condition was previously called “Trench Foot”, as it was seen commonly in soldiers who spent long periods of time in the trenches of World War I. When seen in areas other than the feet, this condition is referred to as “chilblains”.  Immersion foot appears similar to frostbite, but might have a more swollen or “juicy” appearance.


The earlier that cold-related injuries are recognized and treated, the more likely the victim will recover without permanent damage. Frostbite or Immersion Foot is treated with a warm water (no more than 104 degrees F) soak of the affected areas.  This is different from treatment of general hypothermia, which is best treated with warm DRY compresses in areas that effectively transport heat to the body core, such as the armpits, neck, and groin.

Follow these tips when treating frostbite or immersion foot:

  1. Carefully monitor every member of your party for signs of frostbite in cold weather. If possible, get out of the cold and begin the rewarming process, even if it is just placing the victim’s hands in their armpits.
  1. Don’t allow thawed tissue to freeze again. The more often tissue freezes and thaws, the deeper the damage (think about what happens to a steak that goes from the freezer to outside and back again). If you can’t prevent your patient from being exposed to freezing temperatures again, you should wait before treating, but not more than 24 hours.
  2. Don’t rub or massage frostbitten tissue. Rubbing frostbitten tissue will result in damage to already injured tissues.
  3. Don’t use heat lamps or fires to treat frostbite. Your patient is numb and cannot feel the frostbitten tissue.  As a result, significant burns can occur.

Rapid action to rewarm cold-damaged tissues is the key to preventing long-term damage from exposure. Monitor your team members closely, and you’ll have the best change to succeed, even if everything else fails.

Joe Alton, M.D., aka Dr. Bones the Disaster Doctor


Hey, don’t forget to check out our entire line of quality medical kits and individual supplies at Also, our Book Excellence Award-winning 700-page SURVIVAL MEDICINE HANDBOOK: THE ESSENTIAL GUIDE FOR WHEN HELP IS NOT ON THE WAY is now available in black and white on Amazon and in color and color spiral-bound versions at

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