In cases of frostnip, the mildest form, the skin begins to freeze and turns white. Sensation in the area begins to fade. Damage can be prevented by drying and gently rewarming the skin against another area of warm skin. Continued exposure to cold will cause the tissue to freeze and frostbite to develop. True frostbite causes permanent damage to the frozen tissue.
Blisters usually form, along with a thick black scar.
Gangrene can occur with loss of a toe or finger in severe cases. Superficial frostbite will occur if the exposed area is not rewarmed after frostnip occurs. In such cases, the skin becomes white and cold, but the tissue beneath is still soft. Treatment involves rapidly rewarming the area if there is no danger of refreezing. The affected area should be submerged in a warm water bath for 20-30 minutes or until color returns.