health

Frostbite is caused by exposure of skin and underlying tissues to extreme
cold. When the skin is exposed to temperatures at or below 32°F (0°C),
the blood vessels in the skin start to constrict. This closing down of the
blood flow in the extremities is the body’s protective strategy for
preserving normal body temperature in the body core (the heart and other
internal organs).
The early stage of frostbite is sometimes called frostnip. Short-term
symptoms include loss of feeling or aching pain in the affected
part, followed by redness of the skin and tissue swelling. Long-term
symptoms include intense pain in the affected part, tingling sensations,
cracks in the skin, dry skin, loss of fingernails, joint stiffness, loss of bone
or muscle tissue, and increased sensitivity to cold. If left untreated,
frostbitten skin gradually darkens and blisters after a few hours.
Skin destroyed by frostbite is completely black, looks burned, and may
hang loosely from the underlying tissues.