Frostbite and hypothermia



Exposure to low temperatures can have various consequences on the body, capable of creating even permanent damage to the point of death.

When, due to cold waves, the human body is unable, through thermoregulation, to maintain the body temperature around 37 ° C and there is a drop below 35 ° C, we speak of hypothermia of the organism (or frostbite).

Hypothermia is characterized by the slowing of blood circulation caused by the body to avoid heat loss.

There may be different levels of hypothermia based on the "intensity of the cold and the duration of exposure to low temperatures:

  • mild hypothermia, up to body temperatures of about 32 ° C. It is characterized by paleness of the face and body, the presence of continuous chills, rapid heartbeat (due to the involuntary mechanisms that the body puts in place to decrease the dispersion of heat in response to low temperatures), joint and muscle pain associated with "onset of frostbite of the extremities
  • moderate hypothermia, body temperature between 32 and 26 ° C. In addition to mild hypothermia disorders, there is a state of confusion or drowsiness, irregular heartbeat (arrhythmia), slow breathing and muscle stiffness
  • severe hypothermia, body temperature below 26 ° C. Vital functions are compromised and there is loss of consciousness and death due to cardio-respiratory arrest


In mild and moderate hypothermia, cooling of the extremities, such as hands and feet, and poor blood supply can lead to freezing, ie damage to the skin and soft tissues caused by exposure to temperatures below zero, due to lack of oxygenation and heat.

As with hypothermia, there can be different levels of freezing based on the intensity of the cold and the duration of exposure; in severe cases of prolonged oxygen deficiency due to lack of blood flow in the tissue, the damage can be permanent. cause of cell death (cell necrosis) with the appearance of gangrene (or more commonly gangrene) and invasion by bacteria.

The latter eventuality can be treated with antibiotic therapy but, to avoid the spread of the infection to the rest of the body, the affected part of the body must be amputated.

Freezing can affect any area of ​​the body, but the parts that can be most easily damaged are those normally most exposed to cold and wind, even if covered, such as:

  • nose
  • ears
  • fingers and toes
  • cheeks
  • chin
  • lip

The first signs are usually cold and severe pain in the affected body part.

The people most at risk are those who work outdoors for a long time at very low temperatures, homeless people who live outdoors and the victims of mountain accidents.

Knowing how to recognize the first signs of frostbite and how to intervene in first aid can be key to reducing the risk of permanent injury.


The severity of frostbite depends on the level of tissue damage and its depth.

There are different stages of frostbite, the mildest and most moderate one affects only the superficial part of the tissues (skin) and does not cause permanent damage to the affected area.These are, in fact, skin lesions reversible in 2-3 weeks, often also referred to as chilblains, which appear if the skin exposed to the cold is wet or there is strong wind.

The first complaints (symptoms) consist of a feeling of cold and pain in the affected area.

Other signs that can put you on alert include:

  • mild numbness of the affected area
  • ache
  • numbness, tingling (paraesthesia)
  • red skin that tends to white over time
  • burning
  • swelling from fluid accumulation (edema)

At this stage, if not taken immediately, the frostbite extends to the deeper layers of the skin and other tissues, including blood vessels and muscles, which can be permanently damaged. In this case, the color of the skin first becomes white and then bluish, the sensation of numbness increases and the sensation of being stung by needles or pins may appear.

If frostbite persists, the affected area gradually loses sensitivity to cold and pain. Later, it becomes cold, completely numb due to degeneration of nerve endings, grayish or black in color and hard to the touch.

Later, areas of gangrene appear (a symptom of cell death).

Rewarming frozen skin can initially cause pain, swelling, and discolouration, and blisters may form, which in severe cases may fill with blood 24 to 48 hours after rewarming.


The most common cause of freezing is long-term exposure to cold climatic conditions (below freezing). The risk increases when the temperature drops below -15 ° C. In case of very cold wind (-27 ° C), frostbite can occur on exposed skin in as little as 30 minutes.

Specific conditions that lead to freezing include:

  • wear clothing unsuitable for the climatic conditions
  • staying out in the cold and wind too long
  • direct contact with ice, frozen metal or very cold liquids

Injuries caused by frostbite derive from an association of several factors. The body responds to cold temperatures by narrowing the superficial blood vessels: consequently, the flow of blood to the extremities slows down, less heat is lost and the blood is directed to the vital organs, to keep their temperature in balance.

In the absence of adequate amounts of blood and, therefore, of heat and oxygen, the extremities and the surface of the body become colder and colder and the fluid present in the tissues can freeze into ice crystals that damage cells and tissues in the affected area. prolonged lack or absence of oxygen to cells can cause cell death (necrosis).

Factors that increase the risk of frostbite are:

  • dehydration
  • excessive sweating
  • diabetes
  • peripheral circulatory problems
  • alcohol or drug abuse (in particular alcohol facilitates the dispersion of heat)
  • smoke (due to its vasoconstrictive action)
  • previous frostbite injuries
  • being at a high altitude (for the reduction of oxygen supply to the skin)

People suffering from mental disorders and diseases typical of old age, such as dementia or Alzheimer's disease, may be more at risk than others, as they do not always perceive the cold adequately and due to the action of certain drugs (psychotropic drugs ) have poorly functioning thermoregulation mechanisms.

Even children, having a lower ability to retain body heat, may be more prone to frostbite than adults.


The assessment (diagnosis) of frostbite is based exclusively on the medical examination which highlights the typical signs of significant exposure to cold (in terms of temperatures and duration).

Sometimes, the first signs present may be similar to those of injury not caused by cold, but over time the frozen tissue takes on its own distinctive characteristics.

The doctor may also decide to do an X-ray, bone scan, or MRI to determine the severity of the frostbite and check for damage to bones or muscles as well.

In some cases, it may be necessary to perform multiple checks over time because the true extent of a frostbite injury is often not immediately apparent.


The treatment (therapy) of frostbite damage or hypothermia cases varies according to the severity of the condition and the final results are highly dependent on the speed of first aid.

If a person has signs of hypothermia (lowering of body temperature below 35 ° C), first aid must be aimed at restoring body temperature, to avoid damage to vital organs and the appearance of the effects of freezing.

For this purpose it is advisable to take the person to a heated and sheltered from wind and humidity, call a doctor or help for transport to the hospital and, while waiting for their arrival, replace cold or wet clothes, warm the body taking care not to expose it to temperatures higher than 37 ° C (using either hot cloths or lukewarm water).

It is advisable to hydrate the body by administering lukewarm drinks.

Any massages to reactivate the circulation must be light to avoid causing trauma to the frozen skin, preferably performed by medical personnel.

The administration of alcoholic beverages is absolutely to be avoided.

In the event of freezing, in general, the longer the area remains frozen, the more severe the final damage will be. Treatment, whether in hospital or not, mainly consists of heating the affected area and treating the injured parts.

If you feel the signs of a frostbite and are unable to get immediate treatment, some first aid precautions can be taken:

  • enter a warm environment, as soon as possible
  • remove wet clothing and cover the frozen area with dry clothing, but not too hot
  • if your feet or toes have been affected, avoid walking
  • do not rub or massage the frozen area, because tissue damage may occur
  • warm the affected area until the skin is soft again, placing it in warm water (about 40 ° C) or applying warm compresses for at least 30 minutes or, if this is not possible, using body heat (for example, using the armpit to warm frozen fingers)
  • do not use direct heat, coming from hairdryers, stoves, fireplaces to warm up: since freezing makes the area numb, there is a risk of causing burns
  • avoid defrosting the part if there is a risk that it will refreeze shortly, only a worsening of the situation would occur
  • drinking hot drinks, such as tea, coffee, or broth

If your skin turns red and you feel tingling and burning as it warms up it is a sign that normal blood flow is being reactivated.

Instead, seek help from the emergency services by going to the emergency room or calling 911 if numbness or pain persists during warm-up or if blisters develop.

If the pain is very severe you can take a pain reliever medication, but you should consult a doctor before doing so.

In the hospital

In the most serious cases it is necessary that the person is taken to hospital as soon as possible in order to be able to administer all those treatments that otherwise would not be possible: support for breathing, blood flow, treatment of complications.

Since thawing generally causes severe pain, your doctor may also prescribe analgesics by injection.

The treatments may be necessary for several days and, in any case, until there are clear signs of recovery of the part of the body concerned, such as the return to a normal skin color and the reconstitution of the damaged tissues.

During the heating phase, the skin can discolor, crack and blisters can form: in this case it is necessary to keep the area clean, dry and disinfected to avoid possible infections. Usually, however, antibiotic drugs are used for prevention.

After thawing, the affected area is in each case gently wrapped in sterile bandages. If the feet or hands were frozen, the respective fingers are bandaged separately. At this stage, movement must be limited as the fabrics are still very delicate.

If the frostbite is superficial, new pink skin will form under the discolored skin and scabs.

In most cases, the affected area heals within 6 months, sometimes surgery is needed to remove dead tissue.

In severe cases, the person is kept under close observation to assess over time (days, but also weeks) whether the thawed tissue is still alive or dead (necrosis). In this last case, surgical amputation is required.

When there is a very high risk of severe tissue damage, the specialist may decide to use the therapy thrombolytics (tPA) which, if used in the first 24 hours after the onset of the lesions, could reduce the incidence of amputations. The therapy consists of the administration of drugs capable of breaking down blood clots (thrombolysis) formed in frozen blood vessels, in so as to promote blood flow to the damaged part, stimulate healing and prevent further damage.


Hypothermia and frostbite can be prevented mainly by staying as warm as possible and observing some precautions:

  • limit the time spent outdoors in very cold weather, or when a drop in temperatures or a strong cold wind is expected
  • dress in multiple layers, preferably wool, and with waterproof and windproof clothing, to protect yourself from wind, snow and rain
  • wear gloves and a scarf and a headdress, which also protects the ears
  • change wet clothing, as soon as possible
  • pay attention to the first signs of freezing, such as red or pale skin, tingling and numbness
  • immediately seek a sheltered and warm refuge, at the first signs of freezing
  • bring spare clothing and provisions, if you go to the mountains, in order to protect yourself if you get stuck
  • drink fluids, preferably warm, and eat adequate food
  • do not drink alcohol, if you have to stay in the cold for a long time. Alcohol, in fact, facilitates the dispersion of heat
  • stay in motion, physical exercise helps blood circulation


Complications resulting from frostbite depend on the severity of the damage suffered and can include a number of long-term effects, both temporary and permanent:

  • increased sensitivity to cold
  • numbness or long-term poor sensation (chronic), in the affected area
  • excessive sweating (hyperhidrosis)
  • changes in skin color
  • nail changes or loss
  • joint stiffness (frostbite arthritis)
  • infections
  • gangrene (tissue decay and death resulting from an "interruption of blood flow to the affected area) which may require amputation
  • hypothermia
  • persistent pain over time (chronic)
  • increased risk of developing frostbite again


Mayo Clinic. Frostbite (English)

NHS. Frostbite (English)

Laskowski-Jones L, Jones L G.Frostbite: Don "t be left out in the cold. 2018; Nursing, 48: 26-33

In-depth link

Ministry of Health. How to protect yourself from the cold. Guide for prevention

Ministry of Health. Effects of cold on health: what to do while waiting for help

Editor'S Choice 2022

Chili pepper

Chili pepper

Chilli is a plant belonging to the Solanaceae family grown all over the world and commonly used as a spice in kitchens all over the world. It is rich in minerals, vitamins and some polyphenols which can have beneficial effects

Bathing waters

Bathing waters

The "bathing waters", that is to say waters in which it is possible to 'bathe' and carry out recreational or sports activities, must be 'clean', i.e. free from both microbiological (due to the presence of microorganisms such as bacteria, viruses) and chemical contamination



Tachycardia consists of an increase in the number of heart beats which occurs even in conditions of rest and in the absence of physical activity, stress