The forehead repeated closed mouth acne due to sebum secretion, endocrine disorders, inflammation and other reasons. 1. Excessive sebum secretion: The sebaceous glands in the forehead are richly distributed, and excessive oil secretion will cause the skin surface to be oily and easily contaminated with environmental pollutants, and untimely cleaning will easily lead to clogging of the skin pores and the formation of closed-cell pimples. 2. Endocrine disorders: sebaceous gland hyperplasia and lipid secretion of the main triggering factors, especially during puberty androgen levels rise, resulting in abnormal growth and secretion of follicular sebaceous units. 3. Inflammatory response: Propionibacterium acnes in the follicular sebaceous gland units stimulate the hair follicles by breaking down the free fatty acids produced by sebum, causing hyperkeratosis of the follicular sebaceous gland ducts, and at the same time generating a localized inflammatory response, which deepens the severity of acne. In addition, recurring forehead acne is also associated with a diet high in sugar, spicy and stimulating foods, sleep disorders and stress. It is recommended to go to a regular hospital for timely treatment of recurring acne on forehead.