There are more reasons for having a closed mouth on the chin, bacterial infection, staying up late, love of spicy and irritating food, love of sweets, etc. are all prone to cause a closed mouth on the chin. Closed mouth is the scientific name of closed acne, which is caused by the blockage of the follicle opening of the skin and the poor metabolism of sebum. Excess sebum accumulates in the follicular opening and breeds Propionibacterium acnes, the metabolites of which stimulate the hair follicle and form a closed mouth. Androgens accelerate sebum secretion, and too much epidermal sebum exceeds the metabolizing ability of the hair follicles, blocking the pores and forming a closed mouth. Diet not pay attention to moderation, love to eat spicy stimulating food, sweets, cause will stimulate sebum secretion. The chin closed mouth can be used topical retinoic acid cream, adapalene gel and other topical treatment, if necessary, needle clearing treatment. It is recommended to follow the doctor’s instructions for treatment of occlusion, do not self-medication, so as not to cause adverse effects.