Merck Manual

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Quick Facts

Frostbite

By

The Manual's Editorial Staff

Last full review/revision Mar 2019
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What is frostbite?

Frostbite is an injury where a part of your body freezes. The frozen tissue dies and can't come back to life. Cold also can damage tissue without freezing it. This is called nonfreezing tissue injury.

  • Frostbite can make your skin numb, white, swollen, blistered, or black and leathery

  • With severe frostbite, you may lose parts of your fingers, toes, nose, or ears

  • Warm up frostbitten areas in warm water

  • Don't rub frostbitten areas—you could damage the skin and tissue

See a doctor right away if you think you have frostbite.

What causes frostbite?

Frostbite happens when very cold temperature freezes your skin. With severe frostbite, tissue under the skin freezes too.

Any cells that are frozen die. They don't come back to life after they're thawed. The dead tissue can get infected easily.

Nearby cells that aren't frozen can be damaged by the cold. They might survive if they're warmed up quickly but may still die later. It can take a long time to tell whether some tissue will survive.

You have a higher risk of getting frostbite if you're out in cold weather and:

  • You're wet

  • There's a strong wind

  • You're touching metal

  • You have poor blood flow (because of diabetes, for example)

  • Your gloves or boots are too tight

  • Your face, hands, and ears aren't covered

What are the symptoms of frostbite?

Frostbitten areas are numb and feel cold to the touch. Other symptoms depend on how deep the frostbite goes.

  • Shallow frostbite: A numb white patch of skin that peels after your skin warms up

  • Moderate frostbite: Blisters and swelling

  • Deep frostbite: Black and leathery skin (gangrene)

When a frostbitten part warms up, it stops being numb and hurts a lot.

Any black, leathery skin eventually falls off. Sometimes your whole finger or ear falls off. This may not happen for a long time.

After frostbite heals, that part of your body is often very sensitive to cold. It may be permanently numb or painful. Your fingernails and toenails may not look right.

How can doctors tell if I have frostbite?

Doctors can tell if you have frostbite by examining you. Sometimes frostbite looks like nonfreezing tissue injury at first.

How do doctors treat frostbite?

The quicker you warm up a frostbitten part, the better. If you can’t get to a hospital right away:

  • Warm your body up with a warm blanket

  • Put your frostbitten skin in warm water (about 100 to 104° F, or 40° C)

  • Go to a hospital as soon as you can

The warm water is the right temperature if someone else who doesn't have frostbite can keep a hand in it comfortably. Water that's too hot will damage your skin more.

If your feet are frostbitten and you have to walk to get to safety, it's better not to thaw them out first. It's worse to walk on thawed feet than to walk on frostbitten feet. And it's worse if your thawed feet freeze a second time.

Don’t do the following:

  • Rub your skin

  • Put snow around the frostbitten part

  • Warm your skin in front of a fire, or with a heating pad or electric blanket because your numb skin can't tell if it's too hot

Doctors will warm your frostbite in warm water and will also:

  • Give you pain relievers

  • Put antibiotic cream on any broken blisters

  • Keep your skin clean and dry

  • Sometimes give you medicine to improve blood flow or antibiotics to treat an infection

  • Sometimes do surgery to cut away dead skin or amputate a body part

Doctors try to wait as long as they can before doing surgery. Waiting lets them see whether tissue is dead or just badly damaged.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
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