Acne is a chronic inflammatory skin disease of the sebaceous glands with a prevalence of 70% to 87%. It not only affects facial appearance, but also has a psychological and social impact on adolescents that exceeds that of asthma and epilepsy. It is a challenge to successfully treat acne. The treatment of acne varies greatly in the skin field, and it is not a disease that can be cured with simple treatment. Pathophysiological factors of acne Acne is a follicular sebaceous disorder caused by a combination of factors, including excessive sebum production, hyperkeratosis of the follicular opening, proliferation of Propionibacterium acnes, and an excessive immune response. In addition, it is also associated with genetic and psychological factors. Obstruction of the sebaceous glands of the hair follicles is the initial factor leading to acne. Abnormal flaking builds up mixed with filaments and lipid droplets to form microcomedones. The follicles are then filled with lipids, bacteria and keratinous debris, presenting white-headed acne or black-headed acne visible to the naked eye. If Propionibacterium proliferates and produces inflammatory mediators, it develops into inflammatory papules, pustules, nodules and granulomatous damage. Classification and grading of acne Acne lesions manifest in a variety of ways, including papules, pustules, nodules, cysts and even abscesses, sinus tracts, and scarring, with a variety of accompanying symptoms, such as constipation, insomnia, and irritability. Generally, acne can be classified as aggregated acne (pimples, papules, and pustules all occur in clusters), pustular acne (pustules are predominantly pus-filled, with thick pus after breaking, leaving shallow scarring after healing), papular acne (hard papules, light or dark red), pitting acne (blackheads with black heads and yellowish-white translucent fat plugs on the body), atrophic acne (papules or pustules that destroy glands and cause pit-like Atrophic scarring), cystic acne (secondary purulent infection with blood-tinged jelly-like pus flowing out after breaking down), and nodular acne (light red or purplish red, elevated in a hemispherical or conical shape). The grading of acne is an important basis for acne treatment and efficacy evaluation. According to the nature and severity of acne lesions, they can be classified into 3 or 4 grades: Grade 1 (mild), with acne only; Grade 2 (moderate), with inflammatory papules in addition to acne; Grade 3 (moderate), with pustules in addition to acne and inflammatory papules; and Grade 4 (severe), with nodules, cysts or scarring in addition to acne, inflammatory papules and pustules. Acne treatment methods There are many traditional treatments for acne, such as medication, chemical peels, and mechanical exploitation, but there are many problems: due to a lack of understanding of the pathogenesis and process of acne, there is blindness and randomness in the selection of medication, such as antibiotics when acne is predominant; inflammatory damage is still applied alone with vitamin A acid preparations. Chemical peeling and mechanical grinding are not very effective and have more side effects, such as postoperative edema, persistent erythema, and possible postoperative infection, scar aggravation and pigmentation changes. With the development of modern medicine, some new acne treatment methods have gradually been accepted by everyone. Currently, colored light (420nm, 560nm colored light) or fractional lasers (ablative, non-ablative) are commonly used to treat acne as well as acne scars.