There are many reasons for acne on the face, most of them are a combination of factors, the main reasons are abnormal hormone levels, sebum secretion, abnormal keratinization around the hair follicle, inflammatory reaction, other factors such as genetics, drugs and diet, psychological and environmental factors. 1. Main causes (1) Abnormal androgen levels: the key factor in the development of acne. Abnormal androgen levels can affect the secretion of sebum, causing excessive sebum secretion and leading to the growth of acne. (2) Exuberant sebum secretion: androgen level rises during puberty, which promotes the secretion of sebum in large quantities. (3) Abnormal keratinization of cells around hair follicles: this can lead to blockage of sebum excretion or accumulation of oil on the surface of the skin, resulting in the formation of acne. (4) Inflammatory response: Propionibacterium acnes proliferates, breaking down sebum and producing inflammatory factors, inducing an inflammatory response and leading to the growth of acne. 2. Other factors (1) Genetic factors: some patients have a positive family history, often with family aggregation of the onset, so it may be related to genetic factors. (2) Drugs and dietary factors: glucocorticoid drugs, high sugar diet, spicy stimulating food, dairy products may also cause acne. (3) Psychological and environmental factors: mental stress, psychological pressure, high temperature, poor ventilation environment is more likely to induce acne. (4) Others: Smoking and drinking, obesity, premenstrual women can induce or increase the occurrence of acne. There are many reasons for acne on the face, it is recommended to go to the hospital in time, under the guidance of the doctor for standardized treatment.