Pimples refer to acne, the causes of which mainly include excessive sebum secretion, blockage of follicle openings, and propagation of Propionibacterium acnes, as well as hereditary and other related factors. 1. Excessive sebum secretion: The increase of androgens during puberty and other factors can cause the sebaceous glands to secrete excessive sebum, which can easily block the pores and form acne. 2. Obstructed follicle openings: Abnormal keratinization of the cells around the skin follicles can cause the follicle openings to become smaller and blocked, which prevents sebum from being discharged and results in the formation of acne. 3. Propionibacterium acnes reproduction: This is one of the main causes of acne. Fatty acids and other components in sebum are conducive to the growth and reproduction of P. acnes. At the same time, Propionibacterium acnes can damage the tissue around the hair follicles, leading to the spread of inflammation. In addition, heredity, diet, etc. are also factors related to the occurrence of acne. If there is any discomfort, it is recommended to seek medical attention promptly.