Recurrent acne on the chin is usually referred to as acne, which is related to abnormal hormone levels, Propionibacterium acnes infection, and abnormal keratinization of the cells around the hair follicles. 1. Abnormal hormone levels: After puberty, the increased level of androgens in the body may cause the sebaceous glands to enlarge and sebum secretion to increase, while oil and dead skin cells clogging the pores will easily form the symptoms of chin acne. 2. Propionibacterium acnes infection: Propionibacterium acnes is mainly located in the hair follicles and sebaceous glands of the skin. With the development and maturity of adolescents, the secretion of sebum has increased significantly, and the fatty acid composition is suitable for the growth and reproduction of Propionibacterium acnes, which will cause patients to experience recurrent acne on the chin. 3. Abnormal keratinization of the skin around the hair follicles: Abnormal keratinization of the surrounding cells may cause the opening of the hair follicle to narrow, narrow, or even block, and sebum cannot be discharged normally, so it will accumulate in the area of the opening of the hair follicle to form the symptom of chin acne. Repeated acne on the chin should be treated under the guidance of a doctor, and should not be treated blindly.