In winter, some people, especially young and middle-aged women, experience symptoms of frozen face and frozen hands. It manifests as erythema on the face and hands, slight local itching and low skin temperature. Since there are no serious symptoms such as ulceration and erosion, patients do not pay attention to them and miss their condition. In fact, some of the patients with “frostbite” are actually suffering from “systemic lupus erythematosus”. It is true that the cold weather in winter can easily trigger frostbite. However, SLE is related to strong sunlight exposure, so why does it occur in winter? First of all, after the accumulation of strong sunlight (ultraviolet) exposure for several months in summer, the patient is triggered to develop lupus erythematosus just in time for winter. Secondly, as the temperature drops in winter, lupus erythematosus is triggered on the skin exposed to cold air, such as the face and hands, due to impaired blood circulation. Lupus erythematosus is an autoimmune connective tissue disease, mostly seen in women aged 15-40. The cause of the disease is not yet fully understood, and in addition to environmental factors such as ultraviolet light and cold, it is also thought to be related to genetics, sex hormones, drugs, infection and other factors. Clinically, lupus erythematosus is mainly divided into discoid lupus erythematosus, subacute cutaneous lupus erythematosus and systemic lupus erythematosus. Among them, systemic lupus erythematosus is the most serious and can cause damage to the kidney, cardiovascular, digestive, respiratory, mental and other systems if not treated in time. The clinical rash of lupus erythematosus mostly shows erythema-like damage on exposed areas, such as the face and hands, and is easily misdiagnosed as frostbite in winter. So, how can patients check whether they have lupus erythematosus when erythema and other frostbite like damages appear on the face and hands? First of all, patients should pay attention to whether they often feel fatigue, whether they often have low fever, whether they often have mouth ulcers, whether they have joint and muscle pain, whether they easily lose their hair, and whether they have capillary dilated erythema on the palms of their hands and fingers, etc.? If 1-2 of the above conditions are present, you should promptly visit the dermatology department to receive standardized treatment after a clear diagnosis.