Closed-cell acne is mainly related to exuberant secretion of sebaceous glands, abnormal keratinization of sebaceous gland ducts of hair follicles, Propionibacterium acnes infections, hereditary factors, and dietary factors. 1. Excessive sebaceous gland secretion: When the level of androgen in the body is elevated, it will lead to the enlargement of sebaceous glands and the increase of sebum secretion, which may induce closed-mouth acne, and it is more common in puberty. 2. Abnormal keratinization of follicular sebaceous gland ducts: If the follicular sebaceous gland ducts are over-keratinized, it will lead to abnormal duct opening, which will become narrowed or blocked, thus preventing the normal discharge of sebum and the formation of acne. 3. Propionibacterium acnes infection: When the face is infected with Propionibacterium acnes, it breaks down sebum and produces inflammatory molecules, triggering inflammation and promoting the formation of acne. 4. Genetic factors: Acne is hereditary and has a family aggregation phenomenon. If parents suffer from acne, the probability of their children having acne will increase. 5. Dietary factors: long-term large amounts of fat, sugar and other foods that can change the composition of the skin surface lipids or increase the production of sebum, also prone to acne. The face is always long closed mouth acne for a variety of reasons, it is recommended that patients go to a regular hospital to clarify the cause of the disease, targeted treatment, avoid self-extrusion acne, so as not to lead to infection, aggravate the condition.