Back acne may be caused by acne, which has more possible causes, mainly related to increased androgen and sebum secretion, abnormal keratinization of follicular sebaceous gland ducts, poor skin care and other conditions, and poor dietary habits, medications, bad habits, the environment and other factors can also trigger back acne, resulting in the formation of acne. 1. Basic etiology: (1) Increased secretion of androgens and sebum: most common in adolescence, and will be reduced or self-healed after puberty. It is mainly due to the increase in androgen content in the body, which makes the sebaceous glands function vigorously, resulting in a large amount of oil secretion, which will lead to back acne. (2) Abnormal keratinization of the sebaceous gland ducts of hair follicles: this condition will lead to the inability to discharge the rashes and epithelial cells shed from the walls of hair follicles, which will gradually form acne. (3) Poor skin care: If the patient often uses oily cosmetics, the skin barrier will be damaged, which will also promote the formation of acne. 2. Triggering factors: (1) Poor dietary habits: frequent consumption of spicy and stimulating, oily or high-sugar foods can also induce or aggravate acne. (2) Drugs: If patients use sex hormone drugs, glucocorticoids and other drugs for a long time, it can induce back acne. (3) Bad living habits: patients with poor living habits, often stay up late or overwork, etc., will affect sebum secretion, back acne. (4) Environment: If the patient’s working environment requires frequent contact with chlorine, coal tar and other substances or staying in the kitchen for a long time, it can also induce acne. It is recommended that patients with back acne should clarify the cause of the condition and carry out treatment in a reasonable manner.