1, excessive secretion of sebaceous glands: Oily skin is most likely to form acne, and this skin type is often caused by genetics. Of course, poor care can also cause an oil-water imbalance and the formation of acne. Excessive secretion of androgens during puberty can stimulate the sebaceous glands to proliferate. Excessive sweet and greasy foods, spicy and stimulating foods, and dairy products can also make the sebaceous glands secrete more sebum. In addition, office workers, white-collar workers often stay up late, too much stress, depression, introversion, irregular life, etc. can also directly lead to oily skin. Some beauties purposely leave bangs on their foreheads in order to cover up acne. Do not know that the parts that do not see the sun, the secretion of sebaceous glands will greatly increase, acne will be hidden more and more powerful. 2, androgen overproduction: androgens can make the sebaceous glands hypertrophy, sebum secretion increases, and can make the epithelial keratinization of the hair follicle mouth, pore blockage. In adolescence androgen secretion rises sharply, it will lead to acne. Some beauties aggravate acne around the time of menstruation because during this period, estrogen declines and androgens rise relatively. 3, excessive keratinization of the hair follicle mouth: The formation of acne is mainly due to epithelial keratinization of the hair follicle mouth, pore blockage, and sebum discharge. 4.Bacillus acnes reproduction: Each of us has acne bacteria in our hair follicles, which feeds on sebum and produces fatty acids. Under normal conditions, P. acnes helps maintain a weak acidic environment in the stratum corneum and resist the invasion of foreign pathogens. However, if P. acnes overpopulates, it can irritate hair follicles and cause inflammatory acne. P. acnes breaks down triglycerides into fatty acids, which are highly irritating and trigger the release of inflammatory mediators, causing red pimples and even pus, forming cysts and abscesses.