Causes

Frostbite can occur anytime skin is exposed to temperatures below about
28°F. Wind and colder temperatures can increase the risk. Hands, feet, nose, ears, and cheeks are the areas most commonly affected.

Symptoms

• Skin with frostnip, in which only the outermost layers of skin are frozen, may feel numb. It may also appear pale and waxy, and the surface of the skin may feel hard or rubbery.
• With superficial frostbite, all layers of skin are frozen and the skin feels hard all the way through, not just on the top. A frostbitten area is cold, white or grayish-yellow, and hard to the touch. The area may feel very cold and numb, or there may be pain, tingling, or stinging. As the area thaws, it becomes red and painful. Blisters usually form within 24 hours after rewarming.
• With deep frostbite, in which underlying tissue, blood vessels, nerves, muscles, and even bone are frozen, the tissue under the skin also will feel wooden, because it is frozen. Deep frostbite requires prompt medical care.

Prevention

• Pay attention to weather conditions and dress accordingly. Wear a hat or ear muffs, mittens, and a scarf.
• Wear warm clothing. Layers are especially effective for protecting against cold.
• Use the “buddy system”—don’t go out alone in severe weather.
• Avoid alcohol and nicotine when you will be spending time out in the cold. Both reduce blood circulation to the extremities—your fingers, toes, nose, and ears.
• Be alert to signs of frostnip and frostbite. Get out of the cold as soon as possible to prevent further injury.

First Aid

• If you suspect frostnip or frostbite, get out of the cold immediately.
• Warm the affected area by putting the area next to another warm part of your body.
• Warm the affected area by putting it in barely warm, not hot, water
  (100°F).
• Do not rub the frostbitten area. That can cause further injury to the frozen area.
• Do not use dry heat (such as a heating pad), and do not hold the area near a flame to rewarm. You can burn yourself, because you will not have full feeling in the frozen area to warn you when it is getting too hot.
• Drink warm liquids, such as tea, coffee, or hot chocolate.
• Get medical help immediately if the frostbitten area remains numb after you’ve tried to warm it.
• Do not rewarm a frostbitten area if there is a chance that it will freeze again before you can get to shelter and medical help. If you are in the wilderness or otherwise unable to get to help, keeping the frostbitten area frozen will not cause much additional harm. Further serious injury can occur if the area is warmed and then refrozen. Do cover the area, however, to protect it from freezing any deeper while you are trying to get to shelter and medical help.
• Do not pop blisters. Follow your doctor’s treatment plan to prevent infection as the area heals.
• Protect previously frostbitten areas from exposure to cold. Tissue that has been damaged by frostbite will be more sensitive to frostbite in the future.
• Watch for signs of infection as the frostbitten area heals. These include pus or oozing, redness, an odor, or a red line moving away from the injured area.
• You may need a tetanus booster even if frostbite did not involve broken skin. Frostbite may cause skin to slough off later.