Why does the skin turn red in winter ~?

Heat will dilate blood vessels in the skin, leading to facial flushing. Although cold makes blood vessels contract, when the temperature rises, blood vessels will rebound and expand, causing blushing. But some people, at extremely cold temperatures, will also blush because of abnormal blood vessel expansion. The clinical manifestations are filiform, punctate, star-shaped or flaky erythema on the face. When the temperature difference is too large, for example, from the cold wind blowing to the air-conditioned room, it is hot and cold, and the capillaries lose their elasticity in repeated contraction and expansion, which is reflected on the cheeks and nose, which will make the cheeks red and sting. At the beginning, the face can be restored to its original state immediately when it turns red, but if it continues repeatedly for a long time, the blood vessels contract, lose their expansion function, and harden in the state of overstretching, making the face look very red at ordinary times. In severe cases, facial flushing's symptoms will also appear after lowering the head and raising the head. This symptom is relatively calm in spring, summer and autumn, and becomes more serious in winter. In medicine, this situation is called "flushing". Every winter, there are many patients. Blushing is both physiological and pathological. Some healthy people have good peripheral blood circulation, a little activity and rosy complexion; Some people blush when they are shy, angry or ashamed. Some people will blush because of drinking; People living in high mountains need more red blood cells to absorb enough oxygen because the air is thinner, and once the hemoglobin carried by red blood cells increases, the color of their faces will be redder; Some people blush because of menopause, while others blush because of systemic diseases. Such as hypertension, tuberculosis and lupus erythematosus. Don't worry about physical blushing. As for pathological blushing, please consult a doctor. From a medical point of view, blushing means that it is easier to turn red, darker and lasts longer than others due to changes in temperature or mood. There are blood vessels in the skin, which will expand or contract under the influence of nerve factors, especially the capillaries in the cheeks are rich, so the cheeks are more prone to redness. If blushing only occurs in winter, it has more to do with the change of temperature. Generally speaking, heat will dilate skin blood vessels and cause facial flushing. Although cold makes blood vessels contract, when the temperature rises, blood vessels will rebound and expand, causing blushing. But some people, at extremely cold temperatures, will also blush because of abnormal blood vessel expansion. The clinical manifestations are filiform, punctate, star-shaped or flaky faces. When the temperature difference is too large, such as from the cold air to the air-conditioned room, it is hot and cold, and the capillaries lose their elasticity in repeated contraction and expansion, which is reflected on the cheeks and nose, which will make the cheeks red and sting. At the beginning, the face can be restored to its original state immediately when it turns red, but if it continues repeatedly for a long time, the blood vessels contract, lose their expansion function, and harden in the state of overstretching, making the face look very red at ordinary times. In severe cases, facial flushing's symptoms will also appear after lowering the head and raising the head. This symptom is relatively calm in spring, summer and autumn, and it is more serious in winter. In short, the most common saying of blushing in winter is the lack of oxygen or cold.