Pimples usually refers to acne, closed mouth usually refers to whitehead pimples, in addition acne can also appear blackhead pimples, the mechanism of occurrence, symptoms have some differences. 1. Whiteheads: Whiteheads belong to mild grade I acne, when the keratinocytes around the mouth of the local hair follicle proliferate abnormally and sebum is overproduced, its secretion of sebum can be filled with it, then it will form white pimples the size of a grain of corn, with epidermal covering on the surface, and it is not connected with the outside world. 2. Blackheads: When there is more sebum blocking the pores and the keratinized cells around the follicle opening do not completely cover it, its sebum content is not blocked from the air, resulting in the sebum content being directly exposed to the air, which is oxidized, and then black pimples are formed, which is also a mild form of acne. If acne symptoms occur, it is recommended to go to a regular hospital for a clear diagnosis, and once diagnosed, actively cooperate with the doctor to take relevant treatment measures to avoid delaying the condition. Keep the skin clean to avoid damaging the epidermal barrier function.