The redness of the skin on the face may be caused by physiological factors such as living in a plateau for a long period of time, but also by allergic dermatitis, diabetes and other diseases. Patients should go to the hospital in time to find out the cause of the disease. 1. Physiological factors: people who live in plateau and cold areas for a long time may have symptoms of redness on their face due to the obstruction of blood circulation. In addition, menopause, long-term ultraviolet radiation and other factors can also lead to the symptoms of redness on the face. 2. Allergic dermatitis: Allergic dermatitis is caused by contact with allergens and results in redness, swelling, itching and peeling of the skin. The small blood vessels in the patient’s face dilate and the permeability of blood vessels increases, thus causing redness and edema on the face. 3. Diabetes: patients with diabetes have local tissue hypoxia, reduced vascular tone and excessive skin microvascularity, which can lead to symptoms of redness on the face, mainly in the cheeks and cheeks. Patients with red skin on the face should go to the hospital in time, under the guidance of the doctor for regular treatment.