What is the best prevention for frostbite?

The most effective way to prevent frostbite is to limit time in freezing temperatures. When you must be outside, here are some safety tips: Wear layers of warm, moisture-wicking, and windproof clothing. Protect vulnerable areas like your hands, feet, ears, and nose. Stay dry, hydrated, and well-rested. Avoid alcohol, which can increase heat loss. Planning ahead and checking the weather can also help you avoid risky exposure.

Frostbite Symptoms and Treatments

Q: How long before frostbite turns black?

In severe frostbite, skin may turn gray, blue, or black . This usually happens within hours to a couple of days, and the darkening often becomes visible after the skin has been rewarmed. Early signs include pale, numb, or blistered skin. Blackened skin indicates tissue death and requires immediate medical attention to prevent infection and further damage.

Key takeaways:

Frostbite is a type of cold weather injury that can be mild or severe. Severe forms of frostbite develop when tissue is frozen.
Frostbite needs immediate medical attention to avoid complications like amputation. If you suspect someone has frostbite, go to the nearest emergency room.
If help will take time to arrive, you can rewarm skin by placing it in warm water or warming it with body heat. Don’t put the area in hot water or near open flames, and don’t rub the area. All of these things can worsen the damage.

Do you like cold weather, or do you work outdoors in chilly temperatures? If so, you know how important it is to keep warm and stay safe from cold injuries. But while you're working or having fun, sometimes the unexpected happens. If you’ve recently had a cold injury, here’s what you need to know about freezing injuries like frostbite — and when to get treatment.

What is frostbite?

Frostbite is a type of severe cold injury that happens when your skin and the tissue underneath it freeze. It most often affects body parts that are farthest from your heart, like your:

Hands
Feet
Nose
Cheeks
Ears

Mild vs. severe frostbite

Not all cold injuries are the same. Some mild cases of frostbite are reversible with quick treatment, while severe frostbite can cause permanent damage. In the earliest stages, frostbite only affects the surface of the skin. In later stages, freezing extends deeper into tissue, sometimes down to muscles, tendons, and even bone. Severe frostbite often requires surgery or even amputation.

How does frostbite happen?

Frostbite starts when your body tries to stay warm in freezing temperatures. To protect vital organs, it reduces blood flow to your hands, feet, nose, and ears. With less warm blood, these areas cool quickly. If the cold continues, your skin and underlying tissue can freeze. When this happens, ice crystals form inside cells, damaging them and sometimes leading to lasting injury.

What are the symptoms of frostbite and cold injuries?

Frostbite doesn’t develop all at once. The longer people are exposed to freezing conditions, the worse the cold injury gets. As frostbite progresses, people feel different symptoms.

Frostnip

The first stage of frostbite is frostnip. Frostnip is a cold injury, but the skin and tissue aren’t frozen yet. It’s reversible, which means the skin and tissue can completely recover if you can get out of the cold and warm up the area.

Symptoms of frostnip are:

A tingling or stinging sensation in the exposed area
Numbness and decreased sensation to touch in the exposed area
Skin that looks pale over the exposed area
Swelling of the exposed area

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Superficial frostbite

With superficial frostbite, skin and tissue underneath begin to freeze. People may still experience symptoms of frostnip. They also start to develop blisters on the skin. Initial blisters are filled with clear fluid. The skin around them is red and swollen. These blisters can pop, revealing tissue underneath.

Deep frostbite

The most serious type of frostbite is deep frostbite. At this stage, deeper tissue starts to freeze. People develop more blisters, but this time the blisters are deeper and filled with blood. Eventually, as the blisters pop, the skin turns gray, blue, or black. This tissue often can’t be saved.

If frostbite reaches the muscle and bones, these tissues start to die too. This is fourth-degree frostbite. In fourth-degree frostbite, tissue can’t be saved, and people need amputation to prevent injury and infection to nearby healthy tissue.

How do you diagnose frostbite?

A healthcare professional will usually diagnose frostbite by talking with you about what happened and examining the injured area. They’ll look at the color of your skin, check for swelling or blisters, and test how much sensation you still have. These details help them figure out how deep the frostbite goes.

In more severe cases, your healthcare team may order tests to get a clearer picture:

Imaging scans: Specialized tests — like a technetium-99m bone scan or MRI — can show how much tissue is damaged and help predict whether it can recover.
Blood flow tests: Healthcare professionals may use angiography (a test that looks at blood vessels) to see how much blood is reaching the injured area. This information can guide treatment decisions, like whether clot-busting medications could help.
Lab tests: For moderate or severe frostbite, your healthcare team may order blood work to check your electrolytes and look for signs of infection.

These extra tests aren’t needed for everyone. But when frostbite is serious, it can help to have more information. This allows the healthcare team to try and save as much healthy tissue as possible and prevent complications.

What to do if you think you have frostbite or a cold injury?

If you’ve been exposed to cold weather and have frostnip or frostbite symptoms, seek medical attention as soon as possible. Until help arrives, follow these steps:

Move to a warm area.
Remove any wet clothing.
Splint the limb if possible. If you can’t splint it, try not to use the limb or hand. Moving injured tissue can worsen damage.
Sit down. Walking on frostbitten toes or feet can worsen the injury.
If frostbite is mild, you can try warming the area by placing it in warm (not hot) water. You can also use body heat. For example, place fingers under the armpit.
Don’t rub frostbitten areas, as this will make damage worse.
Don’t put frostbitten areas next to a stove or fire. The area will be numb, and you won’t be able to tell if the area is getting too hot. This can result in accidental heat injuries and burns.

When help arrives, expect to spend time at a hospital. You’ll need rewarming therapy and additional treatment like antibiotics and surgery.

How do you prevent frostbite?

Frostbite is a serious injury that can lead to amputation and even death. Even in cases where tissue can be saved, people still have long-term consequences — including bone damage, chronic pain, and arthritis.

To keep yourself safe from frostbite when you’re out in the cold, follow these tips:

Always let someone know where you’re going and when you’ll be back. This way, if you get stuck or stranded without a phone, they can call for help.
Always pack a phone and extra batteries with you.
If you’re stranded, move to a sheltered location away from wind and water.
Wear clothing that wicks away moisture, especially the layer right next to your skin. Damp clothing increases the risk of developing frostbite.
Wear clothing that offers appropriate insulation and wind protection for your top layers.
Use moisture-resistant and wind-impermeable clothing to protect areas at highest risk for frostbite, like the hands, feet, ears, and face. Don’t rely on ointments or other products that promise to protect against frostbite: They might make things worse.
Stay hydrated and rest. Exhaustion and dehydration increase the risk of developing frostbite.
Don’t drink alcohol if you’re going to be out in the cold. Alcohol impairs judgment and can increase heat loss because it causes the blood vessels to dilate.

Frequently asked questions

Frostbite can develop in as little as 30 minutes when exposed to temperatures below -16.6°F with wind chills. In milder conditions, frostbite may take longer to occur. The risk increases with wind, wet clothing, and inadequate protection.

In severe frostbite, skin may turn gray, blue, or black. This usually happens within hours to a couple of days, and the darkening often becomes visible after the skin has been rewarmed. Early signs include pale, numb, or blistered skin. Blackened skin indicates tissue death and requires immediate medical attention to prevent infection and further damage.

The most effective way to prevent frostbite is to limit time in freezing temperatures. When you must be outside, here are some safety tips:

Wear layers of warm, moisture-wicking, and windproof clothing.
Protect vulnerable areas like your hands, feet, ears, and nose.
Stay dry, hydrated, and well-rested.
Avoid alcohol, which can increase heat loss.
Planning ahead and checking the weather can also help you avoid risky exposure.

The bottom line

Some people love cold weather, but chilly temperatures can be dangerous. Freezing injuries like frostbite can happen without proper protection from the cold. So, when you head outside in cold weather, be sure to put on extra layers and prepare for the unexpected.

If you notice signs of frostbite, get medical attention right away. In the meantime, try to rewarm the skin with body heat or warm water. But be careful to avoid further damage with hot water.

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Written by:

Ashely Alker, MD, MSc

Ashely Alker, MD, MSc is an emergency medicine physician and nationally published writer and speaker who focuses on patient education through media and healthcare policy.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

Reviewed by:

Farzon A. Nahvi, MD

Farzon Nahvi, MD, is an emergency medicine physician and author of “Code Gray: Death, Life, and Uncertainty in the ER.” He works at Concord Hospital in Concord, New Hampshire, and teaches at the Geisel School of Medicine at Dartmouth.

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