Common reasons why chin fillers can turn blue include localized vascular damage and infection. Filling the chin usually uses hyaluronic acid to fill the chin, and the phenomenon of chin bluing may occur after the operation. 1. Local blood vessel damage: In general, during the process of filling hyaluronic acid, it is inevitable to touch the local blood vessels and puncture the blood vessels, which will easily lead to the outflow of blood from the blood vessels and the formation of bruises in the subcutaneous area, resulting in a blue chin; in addition, if the filling of hyaluronic acid is too deep, it is easy to puncture the blood vessels and the formation of hematomas in the subcutaneous area, which will lead to a blue and purple chin and the symptom of hard knots. 2. Infection: If patients do not pay attention to local dryness and hygiene after filling hyaluronic acid, it is easy to secondary infection, which will lead to chin bruising. It is recommended that patients according to their own situation, if it is bruising, usually will gradually subside on its own, if necessary, under the guidance of the doctor reasonable treatment.