Acne, often occurs in young men and women between the ages of 15 and 30. It occurs on the sides of the face, forehead, followed by the chest, back, and bilateral shoulders, which are oil-prone areas. The rash can appear as pimples, papules, pustules, cysts, and nodules. Acne begins as a conical papule consistent with a hair follicle, and early sebum accumulates in the sebaceous gland opening to form whiteheads or blackheads. Whiteheads (closed pimples) can be picked out as white beanbag-like material, while blackheads (open pimples) contain sebaceous plugs, caused by the oxidation of sebum; when the condition is slightly severe, inflammatory papules are formed, and small pustules can be found at the top; if the inflammation continues to develop, dark red nodules or cysts of various sizes can be formed, the latter of which have a fluctuating sensation when squeezed. Acne lesions are often symmetrically distributed and are accompanied by more oil production. The course of acne is chronic, sometimes mild and sometimes severe, and most patients gradually remit after puberty, while a few patients are cured in middle age. It can leave behind hyperpigmentation (commonly known as acne marks), hypertrophic scarring or atrophic scarring (commonly known as acne pits). It becomes one of the more common cosmetic skin diseases.