Acne is one of the most common chronic inflammatory diseases in dermatology, mainly affecting hair follicles and sebaceous glands and occurring in adolescence. There are many causes of acne, mainly related to elevated androgen levels, increased sebum production, abnormal keratinization of follicular sebaceous ducts, Propionibacterium acnes infection and secondary inflammatory reactions. The basic process of acne occurrence is as follows: The epidermal cells in the upper part of the hair follicle are blocked to form acne and impede sebum secretion. As internal pressure increases, sebum leaks out causing inflammation, which, together with the proliferation of Propionibacterium acnes, causes infection and pustules. Further progression of untreated disease and increased inflammation can cause localized damage, forming nodules and cysts, and in severe cases, scarring. Elevated androgen levels can lead to enlarged sebaceous glands and increased sebum production. In addition, genetic factors can influence the severity and course of the disease. Dietary factors such as grease and sugar can increase the production of sebum. Pepper, alcohol, overexertion and stress can also aggravate acne. Acne vulgaris is the most common clinical type of acne. It occurs on the cheeks, forehead, and chest and back, often with seborrhea. Mild rashes appear as whiteheads and blackheads, followed by the formation of small pustules that progress to nodules or cysts of varying sizes. Clinically, one or two rashes are often predominant and are usually asymptomatic, and may be painful when inflammation is evident. Acne is a chronic disease that can be mild or severe, and can gradually resolve with age. In addition to acne vulgaris, there are many other specific types of acne, such as acne aggregata, acne fulminans, acne medica, and cosmetic acne. In women, it can also usually appear or worsen before menstruation. In addition, young women with acne, menstrual disorders, hirsutism, hair loss and obesity may be due to polycystic ovary syndrome. Prevention of acne includes: Pay attention to cleaning the face, especially thoroughly every night before going to bed. Use less makeup and clean it promptly to avoid clogging pores, and use less or no oily cosmetics. Cleanse your face with warm water and an oil-balancing cleanser. Do not squeeze with your hands to avoid leaving scars. Eat less spicy and stimulating food, sweets and dairy products, and eat more vegetables and fruits to correct constipation. Work and rest regularly and avoid staying up late. The treatment of acne should be individualized according to the nature and severity of the rash, with the aim of reducing symptoms, preventing recurrence, and preventing scar formation. Currently, the following types of treatment are commonly used: 1. Topical medication 1. Retinoic acid: It helps dissolve acne, reduce inflammation and scarring, and is commonly used at 0.025% to 0.1% retinoic acid. Every night before bedtime use once a day, the beginning of the drug with mild irritation, such as local redness, peeling, tightness and burning sensation, but after adaptation can gradually disappear, but also from the low concentration to start. It can be changed to once a week topical application after symptoms improve. Retinoic acid is usually used as the base drug for acne combination treatment and maintenance. 2. Benzoyl peroxide: It can effectively kill Propionibacterium acnes and dissolve acne. It also has a certain degree of irritation and can be applied from a low concentration. It is also often used as the base drug for combined treatment and maintenance. 3. Antibiotics: Can effectively reduce Propionibacterium acnes. Commonly used are erythromycin, chloramphenicol and clindamycin, but should not be used for a long time single, so as not to cause drug resistance. 4. Azelaic acid: can inhibit Propionibacterium acnes and dissolve acne. It can be used to cause local erythema and stinging pain. Second, systemic drug treatment 1, isotretinoin: oral isotretinoin is the standard treatment for severe acne, and is one of the most effective drugs for acne. It can act on all pathophysiological aspects of acne development and is effective for persistent acne and severe acne. The cumulative therapeutic dose is usually up to 60 mg/kg, which can significantly prevent recurrence and reduce scar formation. Adverse reactions include dryness of skin mucosa, flaking, and elevated blood lipids, etc. Patients may also experience symptoms such as mental depression. In addition, this drug has teratogenic effects, and strict contraception is needed during treatment and for 3 months before and after taking the drug. 2, antibiotics: Oral antibiotics are one of the effective ways to treat acne, especially moderate and severe acne, which can inhibit Propionibacterium acnes infection and inflammation. The first choice is tetracyclines, such as minocycline and doxycycline; secondly, macrolides such as azithromycin and roxithromycin can be chosen. Antibiotics are appropriate in conjunction with other treatments, and require a sufficient course of treatment, such as minocycline can be taken for 6 to 12 weeks. 3, hormone therapy: women can use oral contraceptives such as Daing-35 to antagonize androgens. For patients with severe acne, short-term oral glucocorticoid therapy can be used. Physical therapy 1. Photodynamic therapy: This is a treatment method that has emerged in recent years. It can destroy Propionibacterium acnes and reduce the inflammatory response through drugs and light. The main adverse reactions are pain, swelling, erythema, and flaking. 2.Fruit acid treatment: Fruit acid can reduce the adhesion of keratin-forming cells, accelerate the shedding and renewal of epidermal cells, as well as moisturize, dissolve acne, and reduce the effect of pigmentation. It is suitable for acne, inflammation-based acne. 3, acne scar treatment: scar can be treated by grinding, fractional laser treatment, and for hyperplastic scar can also be used intra-dermal hormone injection.