Frostbite is damage to skin and tissue caused by exposure to freezing temperatures – typically any temperature below minus 0.55ºC (31ºF).
Frostbite can affect any part of your body. However, the extremities, such as the hands, feet, ears, nose and lips, are most likely to be affected.
The symptoms of frostbite usually begin with the affected parts feeling cold and painful. If exposure to the cold continues, you may feel pins and needles before the area becomes numb as the tissues freeze.
When to seek medical attention
If you think you or someone else may have frostbite, call your GP or 111 for advice.
If the symptoms are more severe, or there are signs of hypothermia, go immediately to your nearest accident and emergency department.
To assess the condition, a doctor will first examine the area, check your vital signs and ask how the frostbite occurred.
In some cases, you may be booked in for a follow-up appointment or referred to a specialist in hospital, as the full extent of a frostbite injury is often not apparent until a few days later.
It is important that a person with frostbite is taken to a warm environment as soon as it is safe to do so. This is to limit the effects of the frostbite injury and because they are also likely to havehypothermia. Do not put pressure on the frostbitten area.
The affected area should be warmed up by a medical professional. This is usually done by immersing it in warm (but not hot) water. A bath of water at 40-41ºC (104-105.8ºF) is recommended for re-warming. This process may be very painful and large amounts of painkillers are often required.
It is important not to re-warm the affected area if there is a chance of it freezing again, as this can lead to further tissue damage.
In severe cases of frostbite, there may be tissue loss (gangrene), which requires surgery called debridement so it can be removed, or even amputation.
Almost all cases of frostbite can be prevented by taking precautions during cold weather.
Avoid unnecessary exposure to cold temperatures. The combination of wind and cold temperatures (wind chill) can also cause a rapid drop in temperature, so avoid exposing yourself to the wind where possible.
It is also important to be aware of the early symptoms of frostbite, especially the tingling sensation of frostnip.
Wear appropriate clothing that protects your extremities, such as:
well-insulated boots and a thick pair of well-fitting socks
mitts – they provide better protection against very cold weather than gloves
a warm, weatherproof hat that covers your ears – a surprising amount of heat can be lost through your head
multiple thin layers of warm, loose clothing – these act as insulation
keep dry – remove any wet clothing
If you are travelling during cold weather, plan for emergencies. For example, if you're driving in icy conditions, make sure you keep a warm blanket and some spare clothes in case you break down. If travelling by foot, always let others know where you are going and have a fully charged mobile phone in case of a fall or other accident.
Avoid drinking alcohol during very cold weather. Aside from the risk of falling asleep in the cold when drunk (a common cause of frostbite), alcohol causes you to lose heat at a faster rate.
Smoking also makes you more vulnerable to the effects of the cold as nicotine can narrow your blood vessels.
how to stay warm in very cold weather
What causes frostbite?
The body responds to cold temperatures by narrowing the blood vessels. This slows down blood flow to the extremities to increase blood flow to the vital organs.
As the blood is redirected away from the extremities, these parts of the body get colder, and fluid in the tissue can freeze into ice crystals.
These crystals can cause severe damage to the cells and tissues in the area. The low blood flow also deprives the tissues of oxygen. If blood flow cannot be restored, this eventually leads to the death of the tissues.
Who's at risk of frostbite?
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 time, such as soldiers, sailors and rescue workers
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 medications that constrict the blood vessels, including beta-blockers (smoking can also constrict the blood vessels)
Many cases of frostbite occur in people who have taken drugs or drunk alcohol. This can lead to risky behaviour, not responding normally to cold, or falling asleep outside in cold weather.
As you would expect, cases of frostbite in England often rise during particularly cold winters. For example, during the very cold winter of 2010-11, there were 111 hospital admissions for frostbite. In most years, there are only around 30-60 cases every winter.
If some of your tissue dies, the dead tissue will no longer have a blood supply. This can make the affected body part very vulnerable to infection as your body relies on white blood cells to ward off infections.
Infections associated with frostbite include tetanus and more generalised bacterial wound infections.
More seriously, infection can spread into the blood (sepsis), which requires treatment with antibiotics.
Both conditions require admission to hospital.
Severe frostbite is often associated with hypothermia, which occurs when a person's body temperature drops below 35ºC (95ºF).
Initial symptoms can include:
cold or pale skin
fast breathing (hyperventilation)
Someone with severe hypothermia may be unconscious and have shallow breathing and a weak pulse.
Symptoms of frostbite
The symptoms of frostbite progress in stages. The longer the body is exposed to freezing conditions and the colder the temperature is, the more advanced frostbite can become.
Early stage – frostnip
During the early stage 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, nose, 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 treatment is needed to make sure there is no lasting damage.
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. This is known as deep frostbite and 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 tissue necrosis, and the tissue may have to be removed to prevent infection.
People with a history of severe frostbite often report further long-term effects of frostbite.
These can include:
increased sensitivity to cold
numbness in the affected body parts, most commonly the fingers
reduced sense of touch in the affected body parts
persistent pain in the affected body parts
Treatment for frostbite depends on how severe your symptoms are. You should always seek medical attention if you suspect you or someone else has frostbite.
If the symptoms of frostbite are minor, call your GP or 111 for advice.
If symptoms are severe, go immediately to your nearest accident and emergency department, or call 999 and ask for an ambulance if you cannot move.
If medical assistance is not available, steps can be taken to treat frostbite and hypothermia:
If possible, move to a warmer place – it's best to avoid walking on frostbitten toes and feet as this can cause further damage, although in emergency situations this may not always be possible.
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 from a fire or heater) as this can cause further injury.
Do not allow the person to smoke as this can affect blood circulation.
Re-warming of the frostbitten area
The affected areas need to be re-warmed. Do not try to do this 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 should be done under medical supervision because:
it can be a painful process that requires access to painkillers and expert medical assessment
the best results are achieved using a whirlpool bath that contains a mild antiseptic
The affected area should be re-warmed slowly by immersing it in warm (but not hot) water. A bath of water at a temperature of 40-41ºC (104-105.8ºF) is recommended.
Re-warming should last at least 30 minutes and should only be stopped once the affected body part has a red-purple colour and can be easily moved.
This process can be repeated twice a day until there are clear signs that the affected body part is beginning to heal, such as the growth of new skin and the return of normal skin colour.
As re-warming can often be painful, painkillers are required. Depending on the severity of pain, this may require very strong painkillers such as morphine.
People with frostbite should also take the painkiller ibuprofen as it has additional protective properties for frostbite.
After the frostbitten area has been thawed, it should be wrapped very gently in clean bandages, with the fingers and toes separated. It is very important to keep the skin clean to avoid infection.
Too much movement should be avoided, and the limbs should be elevated if possible. Avoid walking on affected parts that have been re-warmed as the tissues will be very delicate.
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.
In cases of severe frostbite, you will need to be admitted to a specialist unit that has experience in treating these sorts of injuries.
This is often a specialist burns unit, as exposure to very high temperatures can cause the same sort of injury as exposure to very cold temperatures.
If it is thought that there is a very high risk of major damage, you may be given a type of treatment called thrombolysis. This involves giving you injections or medication through a drip in your arm that helps to break up small clots in the frostbitten blood vessels.
This should help improve blood flow to the affected body part, which can help stimulate healing and prevent more damage.
You may also be given antibiotics to prevent the affected body part from becoming infected.
If some of the tissue of the affected body part has died, which is a condition known as gangrene, it will need to be removed. This is known as debridement. In the most serious cases, it is necessary to remove an entire part of the body, such as toes or fingers.
A decision to perform debridement or amputation is normally delayed for several weeks, as often what appears to be dead tissue can heal and recover over time.
Some people are left with permanent problems after frostbite, such as increased sensitivity to cold, numbness, stiffness and pain in the affected area.
Not much can be done to treat sensitivity to cold, numbness or stiffness.
A medication called amitriptyline can sometimes be effective in controlling the pain associated with the long-term effects of frostbite.