Blackheads, or pimples, are a manifestation of acne and may be caused by Propionibacterium acnes infection, endocrine disorders, and abnormal keratinization of the cells around the hair follicles. 1. Propionibacterium acnes infection: the excessive proliferation of Propionibacterium acnes can stimulate local inflammation of the hair follicles, inducing a localized inflammatory reaction. 2. Abnormal keratinization of perifollicular cells: The sebum cannot be discharged due to the small size of the follicle orifice and its blockage, and blackheads can be formed when the accumulated sebum is oxidized by the air. 3. Endocrine disorders: due to elevated levels of androgen and increased sebum secretion, which can induce the accumulation of sebum, thus causing blackheads and pimples. There are many factors leading to the appearance of blackheads and pimples, and patients are advised to go to the hospital and consult the doctor in detail.