Atopic dermatitis is a chronic, recurrent inflammatory skin disease, mainly characterized by intense pruritus, marked eczema-like changes and dry skin. AD often develops in infants and children, and some patients continue throughout their lives, and can seriously affect the quality of life of patients due to chronic recurrent eczema-like rash, severe pruritus, sleep deprivation, dietary restrictions and psychosocial effects. Epidemiology】 After the Second World War, the incidence of AD has increased, and the incidence of AD in children in western developed countries is as high as 10%-20%, and the incidence in adults is about 1%-3%, and some patients can progress with allergic asthma, allergic rhinitis and other allergy-related diseases. The incidence of AD in China is increasing year by year, and the medical burden on patients and society is increasing year by year. The etiology of AD is complex, and it is believed that it may be related to genetics, environmental factors, infection, skin barrier function abnormalities, Th1/Th2 imbalance and neuroimmune abnormalities. It is often accompanied by a personal and family history of atopic disease, in the genetic basis, a variety of environmental factors caused by immune abnormalities. Clinical manifestations] Infancy: also known as infantile eczema, mostly develops 1-6 months after birth and manifests as an acute inflammation with exudation of the skin on the head, face and extensor side of the limbs. The manifestations are skin erythema, papules, papular rash, exudation, crusting, but also light erythema, papules, dryness and mild flaking; often alternating episodes of remission and flare-ups, mostly at the age of 2 years when the rash subsides and healed. Childhood: It often evolves from infancy, and some of them do not go through infancy to childhood directly. The lesions mainly involve the elbow fossa, N fossa, and flexor side of the wrist. The eczema type lesions mainly present as erythema, papules, vesicles, oozing and crusting, but often show chronic damage such as localized skin thickening and hyperpigmentation. The itchy rash type, which occurs on the extremities, presents as scattered dark red or skin-colored papules and nodules with enlarged superficial lymph nodes. Some patients in childhood may develop allergic rhinitis or asthma. In adolescents and adults, the skin is dry and pruritic, the lesions are mainly on the flexor side, the extensor side can also be involved, the lesions on the head and neck, eyelids are severe, the lesions are infiltrated and thickened with lichenoid changes, some manifest as chronic hand dermatitis, and some can be generalized. It may be associated with juvenile cataracts, ichthyosis, periorbital dark halo, dry skin, palpebral sign, periorbital keratosis, labyrinthitis, and easily associated with bacterial, viral and fungal infections. Clinical Classification】 With allergic rhinitis and asthma type; without allergic rhinitis and asthma type. Laboratory tests] Increased blood eosinophils, positive allergen intradermal test or skin prick test, increased total IgE and increased specific IgE in serum.