Frostbite is damage to the skin and underlying tissues caused by extreme cold.

A person with frostbite on the extremities may also be subject to hypothermia (lowered body temperature). Check for hypothermia and treat those symptoms first.

Frostbite is distinguishable by the hard, pale, and cold quality of the skin that has been exposed to the cold for a length of time. The area is likely to lack sensitivity to touch, although there may be an aching pain. As the area thaws, the flesh becomes red and very painful.

Any part of the body may be affected by frostbite; but hands, feet, nose and ears are the most vulnerable. If only the skin and underlying tissues are damaged, recovery may be complete. However, if blood vessels are affected, the damage is permanent and gangrene can follow which may require amputation of the affected part.

Upon warming, it is common to experience intense pain and tingling or burning in the affected area.

Frostbite occurs when the skin and body tissues are exposed to cold temperature for a prolonged period of time. Hands, feet, noses, and ears are most likely to be affected.

Although anyone who is exposed to freezing cold for a prolonged period of time can get frostbite, people who are taking beta-blockers, which decrease the flow of blood to the skin, are particularly susceptible. So are people with peripheral vascular disease (a disorder of the arteries). Other things that may increase the risk of frostbite include: smoking, windy weather (which increases the rate of heat loss from skin), diabetes, peripheral neuropathy, and Raynaud's phenomenon.

The first symptoms are a "pins and needles" sensation followed by numbness. There may be an early throbbing or aching, but later on the affected part becomes insensate (feels like a "block of wood").

Frostbitten skin is hard, pale, cold, and has no feeling. When skin has thawed out, it becomes red and painful (early frostbite). With more severe frostbite, the skin may appear white and numb (tissue has started to freeze).

Very severe frostbite may cause blisters, gangrene (blackened, dead tissue), and damage to deep structures such as tendons, muscles, nerves, and bone.

1. Shelter the victim from the cold and move the victim to a warmer place. Remove any constricting jewelry and wet clothing. Look for signs of hypothermia (lowered body temperature) and treat accordingly.

2. If immediate medical help is available, it is usually best to wrap the affected areas in sterile dressings (remember to separate affected fingers and toes) and transport the victim to an emergency department for further care.

3. If immediate care is not available, re-warming first aid may be given. Immerse the affected areas in warm (never HOT) water -- or repeatedly apply warm cloths to affected ears, nose, or cheeks -- for 20 to 30 minutes. The recommended water temperature is 104 to 108 degrees Fahrenheit. Keep circulating the water to aid the warming process. Severe burning pain, swelling, and color changes may occur during warming. Warming is complete when the skin is soft and sensation returns.

4. Apply dry, sterile dressing to the frostbitten areas. Put dressings between frostbitten fingers or toes to keep them separated.

5. Move thawed areas as little as possible.

6. Re-freezing of thawed extremities can cause more severe damage. Prevent re-freezing by wrapping the thawed areas and keeping the victim warm. If re-freezing cannot be guaranteed, it may be better to delay the initial re-warming process until a warm, safe location is reached.

7. If the frostbite is extensive, give warm drinks to the victim in order to replace lost fluids.

• DO NOT thaw out a frostbitten area if it cannot be kept thawed. Refreezing may make tissue damage even worse.
• DO NOT use direct dry heat (such as a radiator, campfire, heating pad, or hair dryer) to thaw the frostbitten areas. Direct heat can burn the tissues that are already damaged.
• DO NOT rub or massage the affected area.
• DO NOT disturb blisters on frostbitten skin.
• DO NOT smoke or drink alcoholic beverages during recovery as both can interfere with blood circulation.

• There has been severe frostbite, or if normal feeling and color do not return promptly after home treatment for mild frostbite.
• Frostbite has occurred recently and new symptoms develop, such as fever, malaise, discoloration, or drainage from the affected body part.

Be aware of factors that can contribute to frostbite, such as extreme cold, wet clothes, high winds, and poor circulation. This can be caused by tight clothing or boots, cramped positions, fatigue, certain medications, smoking, alcohol use, or diseases that affect the blood vessels, such as diabetes.

Wear suitable clothing in cold temperatures and protect susceptible areas. In cold weather, wear mittens (not gloves); wind-proof, water-resistant, many-layered clothing; two pairs of socks (cotton next to skin, then wool); and a scarf and a hat that cover the ears (to avoid substantial heat loss through the scalp).

Before anticipated prolonged exposure to cold, don't drink alcohol or smoke, and get adequate food and rest.

If caught in a severe snowstorm, find shelter early or increase physical activity to maintain body warmth.

Ulrich AS. Hypothermia and localized cold injuries. Emerg Med Clin North Am. 2004; 22(2): 281-98.

Petrone P. Surgical management and strategies in the treatment of hypothermia and cold injury.  Emerg Med Clin North Am. 2003; 21(4): 1165-78.

Morton PM. Wilderness survival. Emerg Med Clin North Am. 204; 22(2): 475-509, ix-x.