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Frostbite

Page last reviewed: 13/07/2011

Frostbite occurs when the skin and underlying tissue freeze due to exposure to low temperatures. Anyone who spends long periods of time outdoors in cold weather conditions is at risk of getting frostbite symptoms.

Frostbite can affect any part of your body, but the extremities, such as the hands, feet, ears, nose and lips are most likely to be affected.

Types of frostbite

The severity of frostbite, and how quickly it develops, depends on how cold conditions are and the length of exposure.

There are two types of frostbite:

  • Superficial frostbite - only the skin and top level of tissue are affected; a full recovery is likely after the skin and tissue has thawed.
  • Deep frostbite - if deeper tissue becomes frozen and blood vessels are affected, damage from frostbite is more likely to be permanent.

When gangrene (dead tissue) occurs, amputation may be necessary.

Risk groups

Certain groups of people are at greater risk of getting frostbite. They include:

  • people who take part in winter and high altitude sports, such as mountaineers and skiers
  • anyone stranded in extreme cold weather conditions
  • anyone with a job that means they are outdoors in harsh conditions for a long period of time, such as soldiers, sailors and rescue workers
  • homeless people
  • the very young and very old, as their bodies are less able to regulate body temperature
  • people with conditions that cause blood vessel damage or circulation problems, such as diabetes and Raynaud's phenomenon
  • anyone taking drugs that constrict the blood vessels, including beta-blockers and nicotine (smoking)

Glossary

Arteries - Arteries are blood vessels that carry blood from the heart to the rest of the body.

Blood - Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.

Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.

Oxygen - Oxygen is an odourless, colourless gas that makes up about 20% of the air we breathe.

Rupture - A rupture is a break or a tear in an organ or tissue.

Tissue - Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.

Useful Links

Health A-Z: travel health
Health A-Z: Raynaud's phenomenon
Health A-Z: hypothermia

Page last reviewed: 13/07/2011

The signs and symptoms of frostbite vary depending on the extent of injury caused by the cold. Frostbite is usually described as superficial or deep.

Superficial frostbite

During the early stages of frostbite, you will have pins and needles, throbbing or aching in the affected area. The skin will become cold, numb and white, and you may feel a tingling sensation. This stage of frostbite is also known as frostnip, and is common in people who live or work in cold climates. The extremities, such as the fingers, face (nose and ears) and toes, are most commonly affected.

After these early signs, prolonged exposure to cold temperatures will cause more tissue damage. The affected area will feel hard and frozen. When you are out of the cold and the tissue is thawed out, the skin will turn red and blister, which can be painful. There may also be swelling and itching.

This is known as superficial frostbite because it affects the top layers of skin and tissue. The skin underneath the blisters is usually still intact but medical treatment is needed to make sure there is no lasting damage.

Deep frostbite

When exposure to the cold continues, frostbite becomes increasingly severe. The skin becomes white, blue or blotchy, and the tissue underneath feels hard and cold to touch. There may be further damage to tendons, muscles, nerves and bones beneath the skin.

Deep frostbite requires urgent medical attention.

As the skin thaws, blood filled blisters form and turn into thick black scabs. At this stage, it is likely that some tissue has died. This is known as gangrene. The tissue may have to be amputated (cut off) to prevent infection.

Some people have long-term symptoms after recovering from frostbite. This can include loss of feeling in the affected area, and an increased sensitivity to the cold.

Glossary

Aching
An ache is a constant dull pain in a part of the body.
Numb
Numbness refers to a lack of sensation in a part of the body.
Swelling
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Tissue
Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.

Page last reviewed: 13/07/2011

Frostbite is caused when your body is exposed to low temperatures. The severity of frostbite depends on how cold the temperature is and how long you are exposed for.

Factors that decrease temperature and increase the rate at which your body loses heat can have an impact on frostbite developing. This includes:

  • severe weather conditions, such as blizzards
  • wind chill
  • suitability of clothing, and whether your clothing is wet

Damage to the skin and tissue is caused by the body's response to extreme cold.

Blood flow to the extremities, such as the hands, feet, ears, nose and lips, slows down as blood vessels constrict (narrow). This allows an increase in the flow of blood to the body's vital organs in order to keep the body alive. As blood is redirected away from the extremities, these parts of the body get colder. Fluid in the tissue freezes and ice crystals form. These crystals can rupture cells and damage tissue.

Prolonged exposure to the cold can cause further damage. As the temperature continues to drop, the blood vessels dilate (widen) to try to maintain the function of the affected areas. However, because the cells have been damaged by ice crystals, the returning blood leaks out of the blood vessels, causing further damage to the tissue.

Blood
Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.
Blood vessels
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.
Oxygen
Oxygen is an odourless, colourless gas that makes up about 20% of the air we breathe.
Tissue
Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.

Page last reviewed: 13/07/2011

Frostbite can be diagnosed from the signs and symptoms alone. However, it may take a few weeks of recovery to determine the full extent of damage.

If you are at high risk of frostbite, remember that extreme cold has a numbing effect. This means that your skin and tissue may freeze without you realising. It is important to recognise the tingling sensation of frostnip that may lead to the early symptoms of frostbite.

Being aware of the risks and early signs of frostbite means that you can take steps to treat the affected area before deep frostbite develops and any lasting damage occurs.

Numb
Numbness refers to a lack of sensation in a part of the body.
Tissue
Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.

Page last reviewed: 13/07/2011

Preventing frostbite, by taking the necessary precautions before it occurs, should always be your priority.

If frostbite occurs, seek medical attention immediately. If medical assistance is not available there are some steps that can be taken to treat frostbite:

  • If possible, move to a warmer place.
  • Replace wet clothing with soft dry clothing to stop further heat loss.
  • Warm the body by wrapping it in blankets and protecting the frostbitten parts.
  • Do not rub the affected area or apply direct heat (such as a fire or heater) as this can cause further injury.

Re-warming

After frostbite, the affected areas need to be re-warmed. Do not start this process until you are out of the cold. If the warming process is started and the frozen parts are re-exposed to the cold, it can cause further, irreversible damage. Re-warming a frostbitten part of the body can be painful and should ideally be carried out under medical supervision.

The affected area should be re-warmed slowly by immersing it in warm (but not hot) water. A bath of water at 40-42 degrees celcius is recommended. If a tub of water is not available, warm wet-packs can be used. Rewarming usually takes between 20 and 40 minutes. As the affected area gradually starts to warm, its colour and sensation should begin to return.

After re-warming

After the frostbitten area has been thawed, it should be wrapped in clean bandages, with the fingers and toes separated out. It is very important to keep the skin clean to avoid infection. Too much movement should be avoided, and elevate the limbs if possible. Painkillers can be taken to ease any pain.

After re-warming, the skin will be discoloured and blistered. It will eventually scab over. If the frostbite is superficial, new pink skin will form beneath the discoloured skin and scabs. The area usually recovers within six months.

If the frostbite is more severe, the tissue may die and gangrene will develop in the affected area, turning it a blue or black colour. The damage is then permanent and the affected area will either fall off or need to be removed (amputation).

Surgery to amputate frostbitten areas is not usually performed until three to four weeks after the initial injury. This is to confirm the full extent of damage so that no unnecessary tissue is removed. Surgery may be performed before this time if the dead tissue is life-threatening.

Some people are left with permanent problems after frostbite, such as pain, numbness and stiffness in the affected area.

Numbness
Numbness refers to a lack of sensation in a part of the body.
Pain
Pain is an unpleasant physical or emotional feeling that your body produces as a warning sign that it has been damaged.
Physiotherapy
Physiotherapy is a treatment that uses physical movements, massage and exercise to relieve illness or injury.

Page last reviewed: 13/07/2011

Frostbite can occur very rapidly at temperatures below freezing. If you spend any length of time exposed to extreme cold, it is vital to ensure that your skin is well protected.

If you are going to be in cold temperatures for any length of time, your choice of clothing is very important. Make sure that your extremities, such as your hands, feet, nose, ears and lips, are well protected. These are the most vulnerable areas and often the first to be affected. A warm hat, gloves, well-insulated boots and a thick pair of well-fitting socks are all essential.

Wearing a number of thin layers is more effective than wearing a few thick ones. Thin layers trap air that warms to your body's temperature and acts as extra insulation. Your clothes should fit well, and each layer of clothing should be larger than the one below to prevent local pressure and constriction.

If you have a medical condition that causes blood vessel damage or circulation problems, such as Raynaud's phenomenon, or you smoke or take drugs that may restrict your blood vessels, you are more susceptible to frostbite. Make sure that you are aware of the risks.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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