Although snow sports can be great fun, they also bring the risk of frostbite. Trying to warm frostbitten skin or hands by rubbing them together can actually do more damage. Instead, your first priority should be to get out of the elements.
Photo by Trysil
Brittany Lyte writes on Wise Bread:
So if you think you've been exposed to frostbite of this magnitude -- or if you're at all uncertain -- it's important to remove yourself from the elements as quickly as possible and seek professional emergency medical treatment. As you make your way to the medics, keep in mind two important don'ts. Never use friction to warm body parts that have been exposed to frostbite, for this can further damage the tissue. And never rewarm frostbitten skin while you're still out in the elements -- you'll run the risk of refreezing and doubly damaging your skin.
We did a little digging, and authors Gordon Giesbrecht and James A Wilkerson agree in their book Hypothermia, Frostbite and Other Cold Injuries. Get out of the cold first, and avoiding rubbing frostbitten skin. Although rubbing produces heat, it can cause tissue damage due to the embedded ice crystals rubbing against fragile cells.
As with many health-related situations, if you're unsure whether you should seek medical help, err on the side of caution. Don't try to rewarm frostbitten skin while outside, because it can refreeze.