Sudden onset of acne is mainly due to acne and folliculitis. The causes of acne may be related to increased androgen levels, sebum secretion, and blockage of hair follicles; the causes of folliculitis are related to bacterial infections. 1. Acne: After puberty, androgen secretion is exuberant, inducing an increase in sebum secretion and accumulation at the mouth of hair follicles, which can induce acne. In addition, excessive keratinization of the cells around the hair follicles leads to smaller and narrower follicle openings, which prevents sebum secretions from being discharged normally, and is also an important cause of acne. 2. Folliculitis: an acute purulent infection caused by bacteria invading the hair follicles, the pathogen is mostly Staphylococcus aureus. The pathogen is mostly Staphylococcus aureus. Infection can be induced when the human body has low immunity and poor skin hygiene. Due to the complexity of the cause, the specific situation needs to ask the doctor for a face-to-face consultation.