Frostbite is a freezing injury where ice crystals form inside your skin and underlying tissues, damaging cells, blood vessels, and nerves. It happens when skin temperature drops to around minus 4°C (25°F), typically affecting exposed or poorly insulated body parts like fingers, toes, ears, nose, and cheeks. The injury ranges from mild and fully reversible to severe enough to require amputation.
How Frostbite Damages Your Tissue
When your skin gets cold enough, ice crystals physically form in and around your cells. These crystals puncture cell membranes and compress surrounding tissue. But the freezing itself is only part of the problem. As ice forms in your blood vessels, it triggers clotting, blocks circulation, and sets off a chain of inflammation. The combination of direct ice damage and loss of blood flow is what kills tissue.
Your body responds to extreme cold by constricting blood vessels in your extremities to protect your core temperature. That’s why fingers, toes, ears, and the nose freeze first: they’re the farthest from your core, they have a high surface-area-to-volume ratio, and your body deliberately sacrifices their blood supply when it senses danger. This protective response is also why frostbite can set in even when you’re dressed warmly if your extremities are exposed or wet.
What Frostbite Looks and Feels Like
Frostbite progresses through stages, and recognizing the early signs gives you the best chance of avoiding permanent damage.
Frostnip (First Degree)
The earliest stage causes pain, tingling, and numbness in exposed skin. You’ll notice the area looks pale or red, depending on your skin tone, with some swelling. Frostnip doesn’t cause permanent damage. Once you warm the skin, it may peel slightly in the following days, similar to a mild sunburn. You might feel an uncomfortable prickling or burning as sensation returns.
Superficial Frostbite (Second Degree)
At this stage, the freezing has reached deeper into the outer layers of skin and the fat beneath it. The skin may appear white, waxy, or hard to the touch. You’ll likely feel a heaviness or complete numbness in the affected area. When rewarmed, the skin looks patchy and stings or burns. Pale, white, fluid-filled blisters typically form 12 to 36 hours after rewarming. This stage can cause lasting damage but often heals without tissue loss.
Deep Frostbite (Third and Fourth Degree)
Deep frostbite affects all layers of skin plus the muscles, tendons, or bones beneath. The skin turns white or blue-gray and feels wooden or completely numb. After rewarming, large blood-filled blisters appear within 24 to 48 hours. Over the following weeks, dead tissue turns black and hard. Fourth-degree frostbite results in loss of the affected body part, whether through surgical amputation or the tissue separating on its own.
How Quickly It Happens
Frostbite speed depends on temperature, wind, and moisture. The National Weather Service wind chill chart gives a useful benchmark: at 0°F with a 15 mph wind, the wind chill drops to minus 19°F, and exposed skin can freeze in 30 minutes. Stronger winds or lower temperatures shorten that window dramatically. Wet skin freezes faster than dry skin because water conducts heat away from your body roughly 25 times more efficiently than air. Touching bare metal in freezing conditions can cause almost instant frostbite through direct conduction.
What to Do If You Suspect Frostbite
Get out of the cold. Remove any wet clothing and replace it with dry layers. If possible, immerse the frostbitten area in warm water between 38 and 42°C (about 100 to 108°F) for 15 to 30 minutes. The water should feel comfortably warm on uninjured skin, not hot. Rewarming is painful, often intensely so, which is actually a sign that sensation is returning to damaged nerves.
There are a few things that make frostbite worse. Do not rub the frostbitten area with snow, and do not massage it at all. Rubbing causes further mechanical damage to tissue that’s already been shredded by ice crystals. Do not rewarm the area if there’s any chance it could refreeze before you reach safety. Thawing and refreezing causes far more tissue destruction than staying frozen. If you’re still in a remote location and can’t guarantee continuous warmth, it’s better to wait.
For anything beyond frostnip, get to a hospital. Severe frostbite is treated as a medical emergency. Doctors use imaging to assess blood flow to the affected area, and in cases where clotting has blocked circulation to fingers or toes, clot-dissolving medications given within the first 24 hours can dramatically reduce the need for amputation. One study found that patients who received this treatment within 24 hours had a 10% amputation rate compared to much higher rates in those treated later or not at all.
Long-Term Effects of Severe Frostbite
Even after frostbite heals, many people deal with lasting effects. A long-term study of 30 patients with significant frostbite injuries found that 53% developed cold hypersensitivity, meaning their hands or feet overreact painfully to even mildly cold temperatures. Forty percent reported persistent numbness, and 33% had reduced sensitivity to touch. Chronic pain is the most common ongoing complaint, and some people experience intermittent electric shock sensations in the affected area for years.
The underlying cause of these long-term problems is vascular and nerve damage from the original injury. Blood vessels in the affected area may not regulate properly anymore, leading to spasms that reduce circulation, especially in the cold. This makes previously frostbitten tissue more vulnerable to refreezing, creating a frustrating cycle for people who live or work in cold environments. Nerve damage from frostbite resembles other forms of neuropathy, with burning pain, tingling, and altered sensation.
Frostbite can also cause arthritis in the affected joints, sometimes appearing months or years after the injury. This cold-induced arthritis looks and behaves like regular osteoarthritis, with joint stiffness, swelling, and pain. In children, frostbite poses an additional risk: damage to the growth plates in bones, which can lead to deformities as the child grows.
Who Is Most at Risk
Anyone exposed to freezing temperatures can get frostbite, but certain factors increase your vulnerability. Poor circulation from conditions like diabetes or peripheral artery disease means less warm blood reaches your extremities. Alcohol dilates blood vessels near the skin’s surface, which feels warming but actually accelerates heat loss and impairs your judgment about when to seek shelter. Smoking constricts blood vessels and reduces blood flow to fingers and toes. Dehydration thickens your blood and slows circulation. Previous frostbite makes the same area more susceptible to freezing again due to lasting vascular damage.
Tight boots, gloves, or clothing that restricts blood flow also increases risk, even when the gear itself is warm. People who work outdoors, winter athletes, military personnel, and anyone stranded in cold conditions without adequate gear are the most commonly affected groups. Homeless populations face disproportionately high rates of severe frostbite, particularly of the feet.