Freezing of living tissue, when it loses enough heat in below-freezing weather for ice to form.
High winds, wet skin, tight clothes, and alcohol use increase the risk of frostbite. Cell damage, tissue dehydration, and oxygen depletion caused by freezing and thawing can lead to blood-cell disruption, clotting in capillaries, and gangrene . The toes, fingers, ears, and nose are usually affected first, becoming cold, hard, white, or bloodless. The lack of pain is dangerous. Core temperature should be brought to near normal before rapid thawing in warm (under 115 kF [46 kC]) water. Toxoid booster injections are recommended. The outlook is best when freezing is short-term, thawing is by rapid rewarming, and large blisters extending to the end of the part develop early. Tissue that is refrozen after thawing must almost always be amputated. Affected parts become more susceptible to recurrence. Frostbite is best prevented by wearing dry, layered, loose clothing and remaining alert. See also hypothermia .