Atopic dermatitis (AD) is an allergic skin disease with a genetic predisposition. Most patients develop it from repeated episodes of infantile eczema, and 70% of patients have a family history of allergies, asthma or allergic rhinitis, and other genetic allergies, and it is a skin disease with chronic, recurrent, pruritic and inflammatory characteristics. Atopic dermatitis is closely related to genetic factors and allergies. Some data studies have shown that about 60% to 90% of patients are affected by seasonal factors, winter due to cold stimulation, coupled with less time for sunlight exposure, clothing friction, etc. may become triggering factors for atopic dermatitis. Itching and friction can lead to a cycle of itching-scratching-rash-itching. Other etiologic factors include abnormal immune response, abnormal vascular and vascular drug response, neuropsychiatric factors, infection, climate, and living environment. Clinically, atopic dermatitis is divided into simple and mixed types. Simple types are usually not complicated by respiratory symptoms, while mixed types usually present with respiratory allergy symptoms such as asthma and allergic rhinitis. Atopic dermatitis can occur in infancy, childhood, adolescence, or adulthood, and most patients develop it 2-6 months after birth (more than half within 2 years of birth), but it can occur at any age. There are slightly more male patients than female. The main manifestations of polymorphic rash are: erythema, papules, papules, oozing crusts, mossy lesions and skin scratches, dry skin, secondary infections, and mostly pruritus. The distribution and performance of the rash varies by age, so we look at the symptoms of atopic dermatitis in stages: 1. Infancy: the rash is most common on the face, but also on other exposed or friction-prone areas, such as the extremities. The perineum and buttocks are generally less involved. The rash mostly appears as erythema, scattered or fused edematous papules, papules, may have oozing and crusting, itching is intense. Secondary infection or lymph node enlargement is common. The course of the disease is prolonged and recurrent, and changes in the condition can be affected by teething, respiratory infections, emotional stimulation, climate change, etc. 2. Childhood: Atopic dermatitis in childhood can be divided into two types, namely eczema type and itchy rash type. The rash is mostly distributed on the flexor side of the elbow and knee, the side of the neck, the wrist, ankle and so on. The erythema and papules of infancy are gradually replaced by lesions dominated by mossy changes. The itchy rash is particularly common on the extremities and behind the back, and the rash appears as a generalized, sparsely distributed rash of rice-grain to soybean-sized papules with dry, old lesions that are small and hard. The lesions are scratched and often accompanied by local lymph node enlargement. The lesions may be scratched and may become infected with bacteria. The course of the disease is chronic, often recurrent, and can gradually heal or develop into adult-onset atopic dermatitis. 3.Adult stage: Most of them have a history of atopic dermatitis in infancy or childhood. The lesions usually occur on the flexors of the extremities, the neck, and also on the forehead, eyelids, and the back of the hands. Occasionally, the lesions are generalized. The lesions are limited and the rash is mostly mossy or pale red papular patches with fine scales and hyperpigmentation. The affected area is itchy and often becomes infected secondary to intense scratching. The course of the disease is chronic, sometimes mild and sometimes severe, and can eventually be cured gradually with appropriate treatment. In general, the typical patient with atopic dermatitis goes through the three stages of manifestation described above, namely, infancy, childhood and adulthood. However, it is possible to go directly to childhood or adult atopic dermatitis without the infantile stage. Some patients have atopic dermatitis only, and some patients may have rhinitis in addition to other allergic diseases such as bronchial asthma, urticaria, and allergic rhinitis. Individual patients may develop cataracts and retinal detachment. In addition, patients with atopic dermatitis often have dry skin, keratosis of hair follicles, increased palm lines and white skin scarring. Atopic dermatitis is prone to bacterial infections or viral dermatoses. The most common drugs used to treat atopic dermatitis are corticosteroid creams or ointments. In case of infection or severe symptoms, doctors usually recommend taking oral corticosteroids such as prednisone or antihistamines, however, as most people know, most hormones and antihistamines can only temporarily alleviate symptoms and generally play a psychotherapeutic role for itchy patients, which inevitably produces side effects over time. side effects. Similarly, for some children, pregnant women and people with poor gastrointestinal conditions, long-term use or use of corticosteroids may cause stunted growth, obesity, osteoporosis and other side effects, and the condition will often rebound and worsen once the drug is stopped. Infants and children in particular should avoid long-term, large-area use of strong corticosteroid creams or ointments, because these drugs have the function of inhibiting the adrenal cortex. This can have a great impact on the growth and development of the body. For such patients who are not suitable for long-term hormone therapy, immunomodulatory therapy is also an effective method, and BCG polysaccharide nucleic acid injections can effectively alleviate the development of the disease.