Adult acne refers to acne that occurs after the age of 20. Unlike adolescent acne, it is caused by hormonal imbalances due to lifestyle-related habits such as lack of sleep and an unbalanced diet, and by incorrect skin care, which disrupts the skin turnover cycle. In addition, stress can also reduce your immune system, making it easier for you to get acne. Adult acne tends to form on areas with few sebaceous glands, such as the face line and neck. Chemical peeling removes dead skin cells and clogs in pores, so it can be expected to be effective even for "adult acne" that occurs after 20s.