Frostbite occurs when skin and underlying tissues freeze. The most common cause of frostbite is exposure to cold-weather conditions, but direct exposure to freezing materials, such as ice, also can cause frostbite.

Specific conditions that lead to frostbite include:

  • Wearing clothes that aren't warm enough or don't protect against cold, windy or wet weather
  • Not covering skin while exposed to cold temperatures
  • Staying out in the cold too long
  • Touching freezing materials, such as ice, cold packs or metal that's been exposed to freezing temperatures

Frostbite occurs in two ways:

  • Losing body heat. Frostbite can occur in conjunction with hypothermia — a condition in which your body loses heat faster than it produces heat, causing dangerously low body temperature. When core body temperature lowers, it decreases circulation and threatens vital organs. This triggers a "life over limb" response, meaning your body protects vital organs, sometimes at the expense of extremities. With decreased circulation to the skin, your body temperature lowers and the tissue freezes — at about 28 F (-2 C).
  • Direct contact. If you're in direct contact with something very cold, such as ice or metal, heat is conducted away from your body. Such exposure lowers the temperature of the skin and freezes the tissue.
Oct. 07, 2011