What is frostbite?

Frostbite is an injury to your skin and tissues underneath it. It happens when your skin freezes after being exposed to very low temperatures, at or below zero degrees Celsius (0°C) for an extended period.

Frostbite can cause serious permanent damage and complications. With proper preparation, you can greatly lower your risk of developing frostbite. There are different levels of frostbite depending on how severe it is and how much damage it has caused you.

How does frostbite happen?

In temperatures below 0.5 degrees Celsius, the skin and tissues under the skin freeze and ice crystals form, damaging the cells. Blood flow to the affected area slows down and can stop. Frostbite can also happen with prolonged exposure to temperatures below 2 degrees Celsius.

Frostbite is more likely to affect your exposed areas or extremities, such as the fingers, toes, ears, nose, cheeks and chin.

Who is at risk of developing frostbite?

Anybody can develop frostbite. You are at a higher risk of developing frostbite if you:

• are a young child, baby or over 75 years old
• have poor blood circulation because of diabetes, arteriosclerosis or blood vessel spasm
• have a mental illness
• participate in extreme sports such as skiing, hiking or mountain or ice climbing
• are homeless
• are military personnel
• work outdoors

What are the symptoms of frostbite?

Your first sign of frostbite is pain and then numbness. Frostbite symptoms depend on how severe it is and how much skin and tissue underneath it has been damaged.

Frostnip: Frostnip happens before frostbite develops. Your affected skin becomes red, purple or lighter than its natural colour. Your skin will also feel cold, slightly painful and tingly.

Superficial frostbite: Only the surface of your skin has been affected. Your skin may be pale, waxy, hard and numb. It will peel off after you recover. You may also feel pins and needles. You may see swelling around the frostbite. Large clear blisters will develop and they will eventually dry out.

Deep frostbite: Tissues under the skin such as muscle and bone have been affected. You may develop blood filled blisters on white and pale skin. The area may become black.

You may become more clumsy than usual if your hands and feet are affected.

If you don't get warm, you could develop hypothermia.

When should I see my doctor?

You should see a doctor if you develop blisters and damage to your skin after being exposed to extreme cold.

If you still feel numb after you warm up and the feeling does not come back to the affected areas, be sure to see your doctor.

Try not to walk on frostbitten toes or feet — it can make your condition worse.

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How is frostbite diagnosed?

Your doctor can diagnose you with frostbite by examining you and asking about your exposure to cold weather. There are no specific tests.

If your frostbite is severe, you might need x-rays or scans to check how much damage there is.

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How is frostbite treated?

Treatment of frostbite depends on how severe it is. Your doctor will assess your situation and decide if you need to go to hospital for treatment.

Self-care of mild frostbite

If your frostbite is only mild, you may be able to treat it yourself. Get into a warm room as soon as possible and remove any wet clothing.

Put the affected area in water that feels only slightly warm to the touch (around 40 to 42 degrees Celsius). Keep the area in the water until your skin turns pink or does not improve any more. This can take up to 40 minutes and can be painful. You can take pain medicine to help ease the pain. Don’t use direct heat or hot water and don’t massage the area — these can all cause further damage.

Seek medical help if the area blisters.

Treatment of moderate or severe frostbite

If you have moderate to severe frostbite, you should see a doctor as soon as possible. They will warm the frostbitten area slowly and you will prescribe medicines to help manage your pain. The area may blister as it warms. Do not break any blisters that form.

Once the area is thawed, it will be wrapped in sterile dressings. Elevate the affected limb to reduce swelling. You might need to wear a splint or brace.

If you have severe frostbite, you’ll probably need to go to hospital and you may need treatment in a burns unit. This is because frostbite causes a type of injury that is similar to a burn. Recovery can be slow.

If the frostbitten area develops gangrene because the flesh has died, treatment could include:

• removal of damaged, dead or infected tissue
• surgery or even amputation of the damaged area
• medicines, including antibiotics to fight infection and for pain

How can I prevent frostbite?

If you are out in extreme cold, you can protect yourself from frostbite by following these instructions:

• Limit exposure to extreme cold weather — shelter in a warm place when you can.
• Stay dry, because wet clothing quickly chills your body.
• Dress warmly with layers, including a wind-resistant jacket, waterproof boots, gloves, hat and scarf that covers your nose, mouth and ears.
• Avoid tight clothing, jewellery or footwear that could limit blood flow.

Be aware of warning signs of frostbite and take steps to prevent your condition from getting worse:

• Check for symptoms of frostbite (above) on your extremities.
• Look out for numbness or pain — don’t ignore these signs and take steps to get warm and take cover.

What are complications of frostbite?

Frostbite can cause many complications including:

• chronic (long term) pain, including neuropathic (nerve) pain in the affected area
• hypersensitivity to the cold
• frostbite arthritis
• amputation of affected area, for example limbs, ears, nose

Resources and support

• Visit St John Ambulance Australia to learn more about first aid treatment of frostbite.
• If you have any concerns, call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.
• Read more about frostbite from the Emergency Care Institute NSW.