Frostbite

Frostbite is a serious injury that happens when your skin and the tissues beneath it freeze from exposure to very cold temperatures. This condition can permanently damage your body, and in severe cases, may even require removal of affected body parts like fingers or toes.

Table of contents

• What is frostbite?
• Stages of frostbite
• Body parts most commonly affected
• Symptoms
• What causes frostbite?
• Who is at higher risk?
• How doctors diagnose frostbite
• Treatment
• Possible complications
• How to prevent frostbite

What is frostbite?

Frostbite is an injury caused by freezing of the skin and underlying tissues^[1]. It occurs when your skin is exposed to temperatures below 32 degrees Fahrenheit (0 degrees Celsius)^[2]. When this happens, the water in your skin, which makes up over 60% of its content, starts to freeze into ice crystals^[2].

The frozen tissue dies and cannot come back to life^[4]. Nearby cells that aren’t frozen can be damaged by the cold and might survive if warmed up quickly, but may still die later^[4]. It can take a long time to tell whether some tissue will survive.

Frostbite can occur even on skin covered by gloves or other clothing^[1]. You’re more likely to get frostbite in situations that lead to prolonged cold exposure, such as during winter, in windy weather conditions, at high altitudes, or if you don’t have shelter from the cold weather^[2].

Stages of frostbite

Frostbite develops in several stages, from mild to severe^[2]:

Frostnip is the early stage of frostbite. During this stage, your affected skin may be red to purple or lighter than your natural skin tone^[2]. Your skin may feel cold, slightly painful, and tingly. You might experience pain, tingling, and numbness^[1]. Frostnip is the warning stage when skin damage is just temporary and doesn’t cause permanent damage to the skin^[1]. If you notice symptoms, get inside immediately and thaw the affected area of skin with warm (never hot) water^[2]. Afterward, you may notice small red bumps on your skin^[2].

Superficial (surface) frostbite is the second stage and requires medical treatment^[2]. Your skin might feel warm, but the water in your skin is slowly freezing into ice crystals. This can cause a “pins and needles” feeling. Your skin may sting or swell up^[2]. After rewarming, you might have painful, spotty patches or purple or blue areas of skin like a bruise. Your skin might start to peel and feel just like a sunburn. You may also get fluid-filled blisters in the area after a day or so^[2].

Severe (deep) frostbite is the third stage, where your lower layers of skin freeze and total numbness sets in^[2]. It can be difficult to move the area that’s frostbitten or you may not be able to move it normally. The skin can turn black and leathery^[4]. This stage can affect not just the skin but also muscle, bone, and other tissue^[1].

Body parts most commonly affected

Frostbite is most common on the fingers, toes, ears, cheeks, chin, and tip of the nose^[1]. Most often, frostbite occurs in the hands and feet^[3]. Any portion of exposed skin is prone to the damaging effects of frostbite^[5].

Symptoms

Symptoms of frostbite depend on how deep the freezing goes^[4]:

Early symptoms include numbness, tingling, and patches of skin in shades of red, white, blue, gray, purple, or brown^[1]. The color of affected skin depends on how serious the frostbite is and your usual skin color. Your skin may feel cold, hard, and waxy-looking. You might experience clumsiness due to joint stiffness^[1].

Frostbitten areas are numb and feel cold to the touch^[4]. With shallow frostbite, you may have a numb white patch of skin that peels after your skin warms up. Moderate frostbite causes blisters and swelling. Deep frostbite results in black and leathery skin^[4].

Because of numbness, you may not notice you have frostbite until someone points it out^[1]. Changes in the color of the affected area might be difficult to see on brown and Black skin^[1].

When a frostbitten part warms up, it stops being numb and hurts a lot^[4]. Pain and blistering may occur following treatment^[1].

What causes frostbite?

Frostbite happens when very cold temperature freezes your skin^[4]. With severe frostbite, tissue under the skin freezes too. Any cells that are frozen die and don’t come back to life after they’re thawed^[4].

The underlying mechanism involves injury from ice crystals and blood clots in small blood vessels following thawing^[3]. Prolonged duration and lower temperatures increase the likelihood and the extent of the injury^[5].

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, or your face, hands, and ears aren’t covered^[4].

Who is at higher risk?

Frostbite can affect anyone with exposure to cold temperatures^[2]. You’re more likely to get frostbite with prolonged cold exposure, especially if you^[2]:

• Are younger than 18 years of age or are over 65 years of age
• Live and work in cold climates
• Are without housing
• Have an underlying medical condition like peripheral vascular disease (reduced blood flow to parts of the body), malnutrition, Raynaud’s syndrome (a condition where blood vessels constrict in cold), hypothyroidism (underactive thyroid gland), arthritis, or diabetes
• Smoke tobacco products

People who are exposed to low temperatures for prolonged periods, such as winter sports enthusiasts, military personnel, and homeless individuals, are at greatest risk^[3]. Other risk factors include drinking alcohol, mental health problems, certain medications, and prior injuries due to cold^[3].

Homeless populations, children, and the elderly are especially vulnerable to frostbite^[5]. Certain pre-existing conditions may worsen tissue injury because of frostbite, including peripheral vascular disease, malnutrition, Raynaud’s disease, diabetes mellitus, and tobacco use^[5].

How doctors diagnose frostbite

Diagnosing frostbite is based on your symptoms and a review of recent activities during which you were exposed to cold^[7]. Doctors can tell if you have frostbite by examining you^[4]. Diagnosis is based on symptoms^[3].

Your healthcare team may have you undergo X-rays or an MRI (magnetic resonance imaging, which uses magnets and radio waves to create detailed images) to look for bone or muscle damage^[7]. A bone scan or MRI may help in determining the extent of injury^[3]. It may take 2 to 4 days after rewarming to tell the extent of tissue damage^[7].

Treatment

The quicker you warm up a frostbitten part, the better^[4]. Treatment is by rewarming, immersion in warm water (near body temperature), or body contact, and should be done only when a consistent temperature can be maintained so that refreezing is not a risk^[3].

If you can’t get to a hospital right away^[4]:

• 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^[4]. Rapid heating or cooling should be avoided since it could potentially cause burning or heart stress^[3].

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^[4].

Things you should not do^[4]:

• 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

Rubbing or applying force to the affected areas should be avoided as it may cause further damage such as abrasions^[3].

Doctors will warm your frostbite in warm water and will also^[4]:

• 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 (remove) 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^[4].

Frostbite is treated in hospital. Treatments for frostbite include warming the affected body part, removing dead skin, medicines to treat swelling and infection, and surgery if frostbite is severe^[10]. You may have follow-up appointments to check how your wounds are healing and to help with any lasting problems you might have (such as problems with movement)^[10].

Possible complications

Frostbite can cause serious problems, especially if it’s severe^[10]. Complications may include hypothermia (dangerously low body temperature) or compartment syndrome (a serious condition where pressure builds up in muscles)^[3].

It can cause the skin and tissue to die, a condition called gangrene, which may mean the affected body part needs to be removed (amputated)^[10]. With severe frostbite, you may lose parts of your fingers, toes, nose, or ears^[4].

Any black, leathery skin eventually falls off. Sometimes your whole finger or ear falls off. This may not happen for a long time^[4].

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^[4]. Some people have lasting problems after having frostbite, such as pain and stiffness in the affected areas^[10]. You’re also more likely to get frostbite again if the body part is exposed to cold temperatures^[10].

Patients are at high risk for tissue damage that cannot be reversed and tissue death. Patients that survive cold tissue injury are prone to secondary infection and dehydration from loss of the skin barrier^[5].

How to prevent frostbite

Prevention consists of wearing proper, fully-covering clothing, avoiding low temperatures and wind, maintaining hydration and nutrition, and sufficient physical activity to maintain core temperature without exhaustion^[3].

To help avoid getting frostbite, it’s important to wear warm clothing if you’re in very cold temperatures^[10]. For example, you should wear:

• Several loose layers of clothing with a waterproof outer layer
• A hat and scarf to protect your head, neck and face
• Gloves or mittens to protect your hands and fingers
• Thick socks and boots to protect your feet and toes

A way to prevent frostbite is to limit your time outdoors and warm up your body often if you’re exposed to freezing temperatures^[2]. If you believe you have frostbite, go inside or seek shelter from the cold. Then, call your healthcare provider or visit the emergency room immediately to reduce your risk of tissue damage^[2].

At the first signs of redness or pain in any skin area, get out of the cold or protect any exposed skin—frostbite may be beginning^[14]. Protect skin that has been injured by frostbite. Do not expose frostbitten skin to cold temperatures. Sunscreen and protective clothing can protect frostbitten skin from damage by the sun^[16].

• Fingers
• Toes
• Ears
• Nose
• Cheeks
• Chin
• Hands
• Feet

Freezing cold injury, Frostnip