Acne is usually caused by endocrine disorders and Propionibacterium acnes infection. 1. Endocrine disorders: After adolescents enter puberty, if their living habits are not good, such as staying up late, irregular diet, unreasonable diet structure, etc., it will lead to endocrine disorders, androgen secretion, and stimulate sebum secretion to increase, which will block the hair follicles, and thus will cause acne. 2. Propionibacterium acnes infection: Propionibacterium acnes is the normal flora of human skin, mainly found in the sebaceous glands of hair follicles. When the patient’s skin sebum secretion is exuberant, the pores are easy to be clogged, and Propionibacterium acnes produces a lot of free fatty acids, which can cause a local inflammatory reaction of the skin, and ultimately lead to the formation of acne. There may be other reasons for the formation of acne, it is recommended to consult a doctor in a timely manner to clarify the cause of the disease and then carry out targeted treatment to minimize the adverse effects of the disease.