Reddening of the skin after eyebrow tattooing may be related to dye metabolism, skin irritation, skin allergy and other conditions. 1. Dye metabolism: Since the process of eyebrow tattooing involves the use of dye, when the dye is metabolized, or when the dye fades, it can lead to reddening of the skin in the area. 2. Skin irritation: As the process will pierce the epidermis of the eyebrows and inject the dye into the skin, it will cause irritation to the surrounding skin tissues, followed by edema, redness, pain and other symptoms. However, if there is long-term redness and swelling with abnormal secretion, the possibility of infection cannot be ruled out. 3. Skin allergy: If the patient is allergic to the dyes used, uncomfortable symptoms will appear in the areas touched by the dyes, such as itching, rashes or even blisters, redness and so on. Because of the causes of the disease, patients need to go to the regular medical institutions in a timely manner, to clarify the cause of the disease, and if necessary, follow the doctor’s instructions to deal with.