Frostbite is a type of injury in which extreme cold damages the skin and the tissues beneath it.

Extreme cold can cause a range of injuries and conditions, including frostnip, chilblains, frostbite, hypothermia, and trench foot.

Frostbite can cause permanent physical damage and might even lead to amputation.

In this article, we explain the symptoms, causes, and possible treatments for frostbite.

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Frostbite occurs in extremely cold temperatures or after prolonged exposure to freezing conditions.

In extremely cold temperatures, or if a person experiences exposure to freezing conditions for an extended period, blood flow to certain parts of the body can drop to dangerously low levels. Such body parts include the fingers, toes, hands, and feet.

When parts of the body do not receive enough oxygen-rich blood, the cells and tissues may die.

At freezing point, which is 32 degrees Fahrenheit (ºF), or zero degrees Celcius (ºC), a person might begin to feel pain after just a few seconds. This pain is probably caused by frostnip, which refers to the early stages of frostbite. Wet conditions can make it worse.

When temperatures drop to freezing, the blood vessels near the surface of any exposed skin start to narrow in an attempt to preserve heat at the center of the body.

Tiny blood clots might occur as circulation decreases. The tissues and fluids in the affected part may freeze, causing soft tissue to die. Gangrene may result, possibly leading to amputation.

The physical damage from frostbite can be severe and long-lasting.

Frostbite can affect any part of the body but usually occurs on the hands, ears, feet, nose, and lips.

According to the Centers for Disease Control and Prevention (CDA), there were 16,911 deaths due to extreme cold between 1999 and 2011 in the United States. However, not all of these deaths were frostbite-related.

Doctors categorize frostbite in degrees depending on severity in a similar way to burns.

First-degree frostbite, or frostnip

This only affects the surface of the skin.

Early symptoms are pain and itching. The skin then develops white or yellow patches and may become numb. Due to its surface-level impact, frostnip does not usually cause permanent damage.

However, an area of skin with first-degree frostbite may lose sensitivity to heat and cold for a short period.

Second-degree frostbite

This may cause the skin to freeze and harden but does not affect the deep tissues.

After 2 days, purple blisters may develop in areas that froze. These blisters may turn black and become hard, taking 3–4 weeks to heal.

A person with second-degree frostbite who has nerve damage might experience numbness, pain, or total loss of sensation in the area. The decreased sense of heat and cold may be permanent.

Third- and fourth-degree frostbite

In people with the most severe presentations of frostbite, the damage penetrates deeper, causing deep tissue injury.

Muscles, blood vessels, nerves, and tendons freeze. The skin feels smooth and waxy. Some people may lose the use of an extremity, for example, a foot or a hand. For some people, this is permanent.

Complications

People with extreme frostbite might develop gangrene. Gangrene is the death of body tissue. Amputation may be necessary for areas that become gangrenous, such as fingers or toes, to prevent the spread of tissue death.

If the person does not receive swift treatment or if the finger, toe, or limb does not undergo amputation, gangrene may lead to disease throughout the body, which could be life-threatening.

Frostbite can lead to systemic diseases, such as disseminated intravascular coagulation (DIC). In DIC, small blood clots form in the blood vessels. Cardiovascular collapse and sepsis can also occur.

All of these conditions can be fatal. Frostbite is a medical emergency.

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Keeping warm to thaw areas that have frostbite is the main focus of treatment.

Treatment focuses on warming or thawing the frostbitten areas.

However, avoid rubbing or massaging an area to warm up soft tissue that has undergone third- or fourth-degree frostbite as this can sometimes increase tissue damage.

A person with frostbite should move from cold temperatures to a warm room or environment. Remove all wet clothes and replace them with dry ones. Covering a person who has frostbite with blankets will help keep them warm and protect frostbitten body parts.

The warming process should be gradual. A person with frostbite can place affected body parts in warm water until normal color returns. These areas may become red and swollen when normal circulation resumes. Remove the frostbitten area from the warm water once the skin appears to be a normal color.

Avoid direct heat, such as a naked flame. A person may not be able to detect high temperatures in the frostbitten areas, and the individual may burn the area without realizing.

Gently dry the area after removing the body part from warm water. Loosely place a sterile dressing over the area to protect it. A doctor might prescribe an antibiotic to treat any infection or blisters in the skin.

People who spend a lot of time outside in cold weather are at risk of frostbite and other cold-weather injuries. Young children, older people, and those who are homeless are particularly susceptible.

Factors that increase the chance of frostbite include:

  • medical conditions, such as exhaustion, dehydration, circulatory problems, diabetes, hunger, and malnutrition
  • mental illness, panic, or fear, as these may affect decision-making in freezing temperatures
  • cigarettes, alcohol, or drug abuse
  • some medications, such as beta blockers, due to their effects on blood circulation
  • previous injuries from frostbite
  • age, because infants and older people experience more difficulty in retaining body heat
  • wearing constrictive clothing or footwear
  • exposure to wet and windy weather
  • high altitude, because of low temperatures and low oxygen levels

People who have a condition that affects blood vessels and circulation should take extra measures to protect themselves against frostbite.

Anyone planning to spend extended periods outside in freezing temperatures will need appropriate, warm, and waterproof clothing. Those working outside or practicing outdoor winter sports during severe conditions must prepare well to avoid frostbite and other cold injuries.

If a person cannot avoid spending time outside in extreme cold, the following measures can help to reduce the risk:

  • Wearing adequate clothing, preferably in layers, as this traps the warm air inside.
  • Using a waterproof outer layer.
  • Using supplementary oxygen at altitudes of 10,000 feet or above to improve blood flow.
  • Being aware of symptoms, such as redness, tingling, numbness, pins and needles, and pain.

A person starting to show symptoms of frostbite should seek medical attention.