Overview
Frostbite is a freezing injury to the skin and underlying tissue caused by prolonged exposure to freezing or near-freezing temperatures. Extremities such as fingers, toes, ears, and nose are most commonly affected. In severe cases, tissue dies and may need amputation.
How common is it?
Frostbite is uncommon in the UK but becomes relevant during winter sports, mountain activities, and in people sleeping rough during cold spells.
Causes and risk factors
When exposed to extreme cold, the body protects core temperature by constricting blood vessels in the extremities. Reduced blood flow allows tissues to freeze, forming ice crystals inside cells that damage and destroy them.
Common risk factors
- Prolonged exposure to cold below freezing
- Wind chill accelerating heat loss
- Wet clothing or shoes
- Alcohol or drug use impairing cold sensation and judgement
- Peripheral vascular disease
- Smoking (reduces peripheral blood flow)
- High altitude
Symptoms
- Affected area becomes cold, hard, and numb initially (frostnip)
- Skin looks white, grey, or yellow in more severe frostbite
- After rewarming: intense pain, redness, and blistering
- In deep frostbite: loss of sensation, blackening and death of tissue
- Joints and muscles in the affected area may stop working
When to see a doctor
Seek hospital treatment for any area that is hard, numb, and discoloured after cold exposure. Do not rewarm frostbitten tissue if there is any risk of refreezing, as this causes worse injury.
Diagnosis
Clinical assessment of depth of injury. Angiography or MRI can assess blood flow to predict tissue viability. Bone scan may help predict what tissue will survive.
Treatments
Rapid rewarming
In a medical setting, rapid immersion in warm water (37 to 39°C) for 15 to 30 minutes is the standard treatment. Do not rub the affected area.
Medication to restore blood flow
Iloprost (a prostaglandin) given intravenously within 24 hours of injury can dramatically reduce tissue loss by restoring blood flow. Pain relief is also essential.
Wound care and surgery
Blisters are carefully managed. Necrotic (dead) tissue may need debridement or amputation, though this is delayed for weeks as the boundary of viable tissue becomes clearer.
Self-care and lifestyle
- Dress in multiple warm, moisture-wicking layers in extreme cold
- Keep extremities dry and covered
- Carry emergency survival equipment including heat packs when in cold environments
- Never ignore numbness in fingers or toes during cold exposure
Prevention
Dress appropriately for cold weather with waterproof outer layers, insulating middle layers, and moisture-wicking inner layers. Avoid alcohol before cold exposure. Recognise early warning signs and get indoors.