Chilblains (perniosis, also known as pernio) is a reaction to cold, nonfreezing temperatures. It is seen most often in young people who have Raynaud's syndrome and people who are exposed to damp, cold weather.

Symptoms develop 2 to 14 hours after exposure to cold and usually affect the hands, ears, lower legs, or feet. Symptoms include:

• Local redness and swelling.
• Skin bumps.
• Changes in sensation, such as itching or burning.
• Tender blue bumps that develop after rewarming.
• Blisters and ulcers (in severe cases).

Treatment includes rewarming the affected areas, caring for any blisters that form, and avoiding reexposure to cold.