Blood vessels near the surface of the skin constrict to preserve internal body heat. This reduces the blood supply to the skin. As a result, skin tissue freezes and dies.
Skin can also freeze to the surface of a metal object.
Health problems that reduce circulation or weaken the body increase the risk of frostbite. Never massage or rub frostbitten areas and do not apply any ointments. Treatment varies with the type of frostbite. Burning, itching or peeling may occur. The nose, ears, hands, or feet are usually affected.