Blushing can be a normal physiological phenomenon, atopic dermatitis, rosacea, etc. 1. Normal physiological phenomenon: When the weather is hot or when you are nervous or shy, the sympathetic nerves will be more excited and the blood vessels in the face will dilate, and then there will be redness, which is a normal physiological phenomenon. 2. Allergic dermatitis: If you use poor-quality cosmetics, an allergic reaction will occur, which will cause the dilation of small blood vessels in the face, the permeability of blood vessels increases, which will cause redness, usually accompanied by edema or even oozing, itching and other symptoms. 3. Rosacea: Rosacea tends to occur on the face, is a chronic inflammatory skin disease, and vascular dysfunction, skin barrier function damage, etc., will also appear redness, mainly in the middle of the face symmetrical erythema, in the erythema before the emergence of a history of repeated flushing. There may be other causes of redness (seasonal causes, hormonal allergic dermatitis), it is recommended to go to the hospital for examination, to clarify the cause of the disease, standardize the treatment, do not self-medication to avoid adverse effects.