If you're stuck in freezing conditions, you have more than just hypothermia to worry about. Frostbite is when your skin falls below the freezing point and ice crystals form within your skin cells, which kills them. There are two kinds of frostbite -- superficial and severe. If you re-warm your skin in short order, you have the superficial variety. Your skin will form a blister, change from blue to black in color and harden into a shell. This shell eventually falls off to expose new skin underneath if the damage isn't too drastic.
Severe frostbite actually penetrates all the way to the muscle and bone, usually causes tissue damage, and can even lead to amputation of fingers, toes, hands and feet. The stages of frostbite are:
- Red skin -- initial stage
- White skin -- middle stage
- Hard skin -- moderate and approaching severe
- Blackened skin -- advanced stage
With frostbite, it's vital to re-warm your skin gradually. Cover your ears and warm your fingers under your arms. Never rub the damaged skin or submerge it in hot water -- use warm water between 100 and 106 degrees Fahrenheit (37.7 and 41 degrees Celsius). Head to a warmer area immediately, even if it's just a tent. Remove any tight clothing that may restrict blood flow. Put gauze or cloth between your fingers and toes to soak up moisture and prevent them from sticking together. It also helps to slightly elevate the affected area to reduce swelling. As with any medical condition, get to a doctor as soon as you can.