Redness and swelling of the skin caused by overexposure to the cold; also known as chilblains. Pernio occurs chiefly on the hands, feet, and ears. Symptoms include blistering, burning, itching, and ulceration. Treatment is with protection from the cold and gentle warming. Smoking should be avoided because it constricts the blood vessels. Occasionally, medications are prescribed to expand the blood vessels and increase blood flow to the skin.