Cystic acne is usually referred to as cystic acne, which is generally caused by endocrine disorders, microbial infections in the hair follicles, excessive sebum secretion, and hyperkeratosis of the hair follicle epithelium. 1. Endocrine disorders: mostly due to excessive secretion of androgens, related to poor diet and lifestyle habits, or due to polycystic ovary syndrome and other disease-related factors, when excessive secretion of androgens will cause cystic acne. 2. Microbial infection in the hair follicle: it has a certain relationship with not paying attention to skin cleansing, and most of them are Propionibacterium acnes, which can induce cystic acne. 3. Excessive sebum secretion: it may be caused by hereditary factors, or due to excessive cleansing or B vitamin deficiency, when sebum secretion is excessive, cystic acne will appear. 4. Hyperkeratosis of follicular epithelium: When the epithelium of follicular sebaceous gland ducts is hyperkeratotic, it tends to clog pores, leading to the accumulation of sebum and keratin plugs in the pores. This can also cause cystic acne. After the appearance of cystic acne, it is necessary to go to the hospital in a timely manner through the examination to clarify the cause of the disease, and follow the doctor’s instructions to carry out the relevant treatment.