Frostbite: What it is and how to treat it

Oh, we know it's cold. We can feel Jack Frost nipping at our noses. But what about when he gnaws a little harder — what exactly does frostbite mean?

Ice crystals form in exposed skin then freeze the tissue, leading to pain, numbness and possible amputation

Frostbite can be treated fairly easily with no long-term effects but it can also lead to serious injury, including permanent numbness or tingling, joint stiffness, or muscle weakness. In extreme cases, it can lead to amputation. (Justin Fraser/CBC)

The temperature across much of Canada has plummeted to its coldest level this season, triggering warnings about the extreme risk of frostbite.

Oh, we know it's cold. We can feel Jack Frost nipping at our noses. But what about when he gnaws a little harder — what exactly does "frostbite" mean?

People tend to underestimate the potential for severe injuries in the cold, says the Winnipeg Regional Health Authority. We laugh off the sting of the deep freeze, rub our hands back from the brink of numbness and wear our survival proudly like a badge.

That's because, in most cases, frostbite can be treated fairly easily, with no long-term effects.

But it can also lead to serious injury, including permanent numbness or tingling, joint stiffness, or muscle weakness. In extreme cases, it can lead to amputation.

Bitter cold can cause frostbite in just minutes. Here's how to recognize the warning signs and treat them. 0:59

Here's a guide to identifying the first signs, how to treat them, and when to seek medical help.

What is frostbite and frostnip?

Frostbite is defined as bodily injury caused by freezing that results in loss of feeling and colour in affected areas. It most often affects the nose, ears, cheeks, chin, fingers or toes — those areas most often exposed to the air.

Cooling of the body causes a narrowing of the blood vessels, slowing blood flow. In temperatures below –4 C, ice crystals can form in the skin and the tissue just below it.

Frostnip most commonly affects the hands and feet. It initially causes cold, burning pain, with the area affected becoming blanched. It is easy to treat and with rewarming, the area becomes reddened.

Frostbite is the acute version of frostnip, when the soft tissue actually freezes. The risk is particularly dangerous on days with a high wind chill factor. If not quickly and properly treated, it can lead to the loss of tissues or even limbs. 

Signs of frostbite

Health officials call them the four P's:

  • Pink: Skin appears reddish in colour, and this is usually the first sign.
  • Pain: The cold becomes painful on skin.
  • Patches: White, waxy-feeling patches show when skin is dying.
  • Prickles: Affected areas feel numb or have reduced sensation.

Symptoms can also include:

  • Reduced body temperature.
  • Swelling.
  • Blisters.
  • Areas that are initially cold, hard to the touch.

Take quick action

If you do get frostbite, it is important to take quick action.

  • Most cases of frostbite can be treated by heating the exposed area in warm (not hot) water.
  • Immersion in warm water should continue for 20-30 minutes until the exposed area starts to turn pink, indicating the return of blood circulation.
  • Use a warm, wet washcloth on frostbitten nose or earlobes.
  • If you don't have access to warm water, underarms are a good place to warm frostbitten fingers. For feet, put them against a warm person's skin.
  • Drink hot fluids such as hot chocolate, coffee or tea when warming.
  • Rest affected limbs and avoid irritation to the skin.
  • E​levate the affected limb once it is rewarmed.

Rewarming can take up to an hour and can be painful, especially near the end of the process as circulation returns. Acetaminophen or ibuprofen may help with the discomfort.

Do not …

There are a number of things you should avoid:

  • Do not warm the area with dry heat, such as a heating pad, heat lamp or electric heater, because frostbitten skin is easily burned.
  • Do not rub or massage affected areas. This can cause more damage.
  • Do not drink alcohol.
  • Do not walk on your feet or toes if they are frozen.
  • Do not break blisters.

Seek immediate medical attention

While you can treat frostbite yourself if the symptoms are minor — the skin is red, there is tingling — you should seek immediate medical attention at an emergency department if:

  • The exposed skin is blackened.
  • You see white-coloured or grey-coloured patches.
  • There is severe pain or the area is completely numb.
  • The skin feels unusually firm and is not sensitive to touch after one hour of rewarming.
  • There are large areas of blistering.
  • There is a bluish discolouration that does not resolve with rewarming.

Be prepared

The best way to avoid frostbite is to be prepared for the weather in the first place.

Wear several loose layers of clothing rather than a single, thick layer to provide good insulation and keep moisture away from your skin.

The outer garment should breathe but be waterproof and windproof, with an inner thermal layer. Retain body heat with a hat and scarf. Mittens are warmer than gloves because they keep the fingers together.

Be sure your clothing protects your head, ears, nose, hands and feet, especially for children.

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