Frequently Asked Questions

When exposed to the cold (or when the whole person gets cold), the blood vessels of the skin in hands and feet narrow (vasoconstriction) to decrease blood flow in order to reduce heat loss. Without this warming blood flow, the hands and feet cool, as they have few muscles to generate heat, and rely on their blood flow to keep warm). This cooling slows nerve signals, impairs dexterity and eventually results in altered sensation (numbness) [1]. On rewarming, blood flow returns (making the skin appear more reddened, although this can be more difficult to spot in dark skins) and this can be very painful for a few minutes. Afterwards, there may be some altered sensation such as pins and needles or tingling but this does not normally last more than 48 hours.
With NFCI, the affected area is numb with cold for longer than 60 minutes, rewarming pain lasts more than 30 minutes, and the altered sensations arising from nerves (pins and needles, tingling, burning or pain) lasts more than 2 days.

How is NFCI diagnosed?

NFCI is a clinical diagnosis based on a collection of symptoms and signs. The medical history is key (including timing, severity and duration of exposure, symptom sequence) and solely determines the diagnosis in most cases.

What is the difference between frostbite (FCI) and NFCI?

Frostbite occurs in very cold conditions (sub-zero) and involves freezing of the tissues (most commonly fingers, toes and exposed part of the face). The damage to the cells is caused by the formation of ice crystals and the disruption this causes to the fluid in and around the cells [1]. In NFCI, the tissues get cold but do not freeze. It is thought that the reduced blood flow during the prolonged cold exposure causes damage to the blood vessels and nerves [2,3].

What is the difference between Raynaud’s Phenomenon and NFCI?

NFCI is caused by prolonged exposure to cold conditions which causes damage to the blood vessels and nerves in the affected area (usually hands and feet). Raynaud’s Phenomenon (RP) is often idiopathic (the cause is not known, this is often called primary RP) or it is secondary to a more serious condition e.g. scleroderma (sometimes referred to as secondary RP).
Patients with RP and NFCI tend to display different symptoms on exposure to cold. Those with RP experience vasospasm, often within seconds to minutes, expressed as clearly demarcated areas of extreme pallor (which may be followed by blue and red colour changes on rewarming), generally in hands and feet, but which may affect other areas of the body and may happen in response to other triggers too [1]. It is also quite different to NFCI in that it may evolve with time, for example start in the hands and then spread to feet, or symptoms becoming more bothersome as time elapses.
By contrast, individuals with NFCI experience gradual, albeit more rapid than they are used to, cooling of hands and feet when in cold environments, accompanied by pallor and sometimes odd sensations or pain. Altered sensation may persist between bouts of cooling. Increased sweating may be seen in NFCI but is rare.

It is possible for someone to have both RP and NFCI.

What is the difference between Hand-Arm Vibration Syndrome and NFCI?

Hand-arm vibration syndrome (HAVS) is caused by using vibrating power tools (e.g. pneumatic drills) which causes damage to the nerves, blood vessels and muscles of the hands and arms and presents very similarly to Raynaud’s Phenomenon. Symptoms of HAVS include tingling, sensory loss, cold sensitivity and decreased dexterity and grip strength. On exposure to cold, the fingertips of the dominant hand go white and are painful on rewarming. Continued exposure to vibrating tools will increase the severity of symptoms [1]. Symptoms of HAVS are felt when exposed to cold or vibration, whereas NFCI symptoms can also interfere with sleeping.

What are chilblains?

Chilblains or pernio which may occur on finger and toe skin following cold exposure (above freezing). They are small, swollen, itchy spots that may be tender but long lasting effects are rare [1]. They may be associated with NFCI by virtue of arising in response to cold exposure, but are not part of the same condition.

Can you recover from NFCI?

In most cases, symptoms of NFCI will resolve with time [1, 2]. In some severe cases of NFCI, individuals may continue to have cold sensitivity, pain and altered sensation many years after the initial cold exposure.

Can you get NFCI more than once?

It is possible to get NFCI again if exposed to the cold for long enough. Individuals who have had a previous cold injury and still have symptoms of cold sensitivity and hyperhidrosis (excessive sweating in the injured area) may be at greater risk of NFCI, as both of these symptoms will cause the hands/feet to cool quicker. However, if an individual has fully recovered from their NFCI, there is no evidence to suggest they are at greater risk.

Are some people more susceptible to NFCI?

Yes, some individuals are at greater risk of getting NFCI when exposed to the cold.
Individuals of African and Caribbean origin appear to be at greater risk of cold injury [1, 2] . This may be due to a slower rewarming rate after cold exposure [3] possibly due to reduced reactivity of the blood vessels in the fingers and toes [4].
Some individuals feel colder than others, this is sometimes called constitutional cold sensitivity [5], these individuals may have a higher risk of developing NFCI.

For more information about the risk factors for NFCI see RISK FACTORS
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Is NFCI just a military problem?

NFCI is more commonly seen in military personnel, however it has been reported in civilians who have been exposed to cold, and often cold wet conditions for a long time. These include individuals undertaking outdoor sports [1], working in cold environments such as agriculture or fishing [2], those who were incapacitated following an accident [3] and in the homeless [4] and elderly [5].

Can I get NFCI from doing outdoor sports?

NFCI has been reported in athletes such as ice skaters [1], cyclists [2], divers [3], paddle sports [4] and long-distance Polar rowers [5]. Athletes, such as windsurfers [6] and cold-water swimmers, may develop cold sensitivity through cold exposure, although this doesn’t seem to be associated with altered sensation or blood vessel damage [7].
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Can infrared thermography be used to diagnose NFCI?

On its own, infrared thermography cannot be used to diagnose NFCI [1]. There is a wide range in response to standardised cold sensitivity tests [2] and there have been some concerns regarding the reliability of the test [3]. However, gentle exercise prior to the test does appear to improve its reliability [1]. Another difficulty is that some people with NFCI will have normal thermography tests [1, 4], and others with no NFCI may appear to be cold sensitive [4, 5].
At the moment it remains a research tool for NFCI and has no application in clinical decision making or occupational management.

Can nerve fibre density be used to diagnose NFCI?

On its own, intraepidermal nerve fibre density (IENFD) cannot be used to diagnose NFCI. It has been found useful in identifying the damage to nerve fibres which may be associated with NFCI in some cases [1, 2, 3]. Not all cases of NFCI have reduced IENFD [2] and some patients without NFCI will have reduced IENFD for reasons other than cold injury. Thus, it is not necessarily a discriminatory or diagnostic test, but it can add to the picture of NFCI if appropriately interpreted by specialists.

If I have NFCI, do I have to give up activities in the cold (e.g. skiing, kayaking)?

Unless you have severe NFCI, you do not have to give up your outdoor hobbies, but you should take extra precautions when out in the cold. Make sure you are wearing appropriate clothing (windproof and waterproof outer, thermal layers, hat, gloves and waterproof shoes) and exercise to keep warm. You may want to wear heated base layers, gloves and socks to help keep warm. Make sure that you are warm before going outside and go inside before you get cold. Providing your hands and feet don’t cool to the point of loss of feeling for longer than one hour you will not sustain further injury, although you may trigger symptoms if you haven’t fully recovered from an NFCI.

If I have been in the cold and my hands or feet are numb, how should I warm them up?

Firstly, you need to get out of the cold environment to prevent further body cooling. Any wet clothing should be removed and replaced with dry clothes/blankets. The affected area should be rewarmed slowly [1] either by being in warm air or by wrapping extra layers. Hands can also be rewarmed by putting them under your armpit, you may need to use someone else’s armpit to warm your feet!

If I think I have NFCI, what should I do?

Anyone who thinks they have acute NFCI should keep out of the cold and stay warm as soon as possible. Avoid situations that may lead to cooling and keep affected areas warm.

Service personnel should report to their medic/chain of command so that they can be referred to a regional cold injuries clinic. Civilians should seek advice from their GP. Some GPs may not have much experience of treating NFCI and therefore it may help by providing them with this leaflet.

Clinics which provide advice on NFCI can be found here.