Do I have frostbite?

The short answer is that if you have been in below zero temperatures and you now have abnormal changes on your skin, you might.

Typically, the first signs may be that your skin goes through a phase of being cold and numb, and then very painful after rewarming. If your skin looks and feels normal after rewarming to normal temperatures, you probably do not have frostbite.

At first, immediately after thawing your hands or feet, your skin might still look normal or look paler. There might be a faint line or demarcation where the frostbite progressed to.

More severe changes, such as greyish skin or blisters, may take 24 to 48 hours to appear after rewarming. Symptoms may begin as pain, followed by numbness, without further warning.

You can suspect severe frostbite if:

You were exposed to temperatures below -10 degrees Celsius for several minutes to hours.

You were not properly protected from the cold (i.e. skin exposed, clothing too thin or damp; clothing not warm enough).

You feel tingling (“pins and needles” sensation), have pain, or lost sensation in some parts of your body such as fingers, hands, arms, toes, feet, or legs.

What does frostbite look like?

Frostbite looks different before and after being warmed up or “rewarmed.” It will also change with time, from hours to days after the frostbite has happened.

Source: Matt Ryan, Australian Antarctic Division; https://www.abc.net.au/news/2016-07-18/eat-sleep-freeze-repeat-south-australian-doctor-in-the-antarctic/7638608

Frostnip

Frostnip is a mild cold injury and is completely reversible. The skin is not considered frozen and there is no ice formation under the skin. The skin may appear pale, feel numb, and cause pain. After rewarming, no blisters form. Sensation in that area can be reduced and a tingling sensation can persist, but it is not dangerous.

Mild frostbite

Superficial frostbite or mild frostbite may appear red like a sunburn or later have clear blisters. Clear or white blisters are generally a good sign, meaning the frostbite is not too deep.

Severe frostbite

Deep frostbite or severe frostbite may appear grey and dusky (cyanosis) at first, then develop bloody blisters or black, dead skin. Bloody blisters are a bad sign and generally mean there is deeper and more severe frostbite.

Frostbite can be classified by both its depth and by grade, with both these descriptions best applied after the skin has been rewarmed. Many healthcare providers use the grading scale developed by Dr. Cauchy to assess the severity of frostbite:

Click image for larger view.

Source: Cauchy E, Davis CB, Pasquier M, Meyer EF, Hackett PH. A New Proposal for Management of Severe Frostbite in the Austere Environment. Wilderness Environ Med. 2016 Mar;27(1):92-9.