Frostbite

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.

Read more about the symptoms of frostbite.

When to seek medical attention

If you think you or someone else may have frostbite, call your GP or NHS 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.

Treating frostbite

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 have hypothermia. 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.

Preventing frostbite

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.

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
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 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.

Complications

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. Read more information about treating tetanus and treating sepsis.