Closed-cell pimples belong to a kind of skin lesion manifestation of acne, which may be caused by bad living habits, high androgen level, and Propionibacterium acnes infection. 1. Bad lifestyle habits: staying up late, not getting enough sleep for a long time, and consuming too much sweet and spicy food may affect the metabolic function of the skin, resulting in an imbalance of the skin metabolism, which will easily cause closed mouth acne. 2. Excessive androgen levels: When the level of androgen in the body is too high, it can promote excessive secretion of sebaceous glands, hair follicles and sebaceous ducts will be over-keratinized, easy to block the pores, and the sebum is not discharged smoothly, which is easy to form closed-cell pimples. 3. Propionibacterium acnes infection: When there is Propionibacterium acnes infection, its proliferation will stimulate the hair follicles and sebaceous ducts, resulting in abnormal keratinization and hyperplasia, and sebum discharge will be blocked, which will lead to the formation of closed-cell pimples. When the symptoms of acne vulgaris appear, you should take good care of your daily life and seek medical treatment as soon as possible.