Eczema is an inflammatory skin disease caused by a variety of internal and external factors with a pronounced tendency to exude, accompanied by significant itching, prone to recurrence, and seriously affecting the quality of life of patients. This disease is a common disease in dermatology, the prevalence of the general population in China is about 7,5%, the United States for 10,7%. I. Etiology and pathogenesis The etiology of eczema is still unclear. Endogenous causes include abnormal immune function (such as immune imbalance, immunodeficiency, etc.) and systemic diseases (such as endocrine diseases, nutritional disorders, chronic infections, tumors, etc.) and hereditary or acquired skin barrier dysfunction. External factors such as, allergens in the environment or food, irritants, microorganisms, changes in ambient temperature or humidity, and sun exposure can trigger or aggravate eczema. Psychosocial factors such as stress and anxiety can also trigger or aggravate the disease. The pathogenesis of this disease is not clear. At present, it is mostly believed to be the result of a combination of internal and external factors based on internal factors such as abnormal immune function and skin barrier dysfunction. Both immune mechanisms such as allergic reactions and non-immune mechanisms such as skin irritation are involved in the pathogenesis. Microorganisms can trigger or aggravate eczema through direct invasion, superantigen action or induced immune response. The clinical manifestations of eczema can be divided into three phases: acute, subacute and chronic. The acute phase is characterized by erythema, edema on the basis of corn-grain papules, papules, blisters, vesicles and exudate, the center of the lesion is often heavy, and gradually spread to the periphery, and scattered papules, papules, so the boundary is unclear. In the subacute stage, the redness and exudation are reduced, and the vesicular surface is infatuated and desquamated. Chronic eczema mainly manifests as rough hypertrophy, moss-like changes, may be accompanied by pigment changes, hand and foot eczema can be accompanied by nail changes. The rash is generally symmetrically distributed, often recurrent, and the conscious symptoms are pruritus, or even severe itching. Laboratory tests are mainly used for differential diagnosis and screening of possible causes, routine blood tests can have eosinophilia, there can also be increased serum eosinophilic cationic protein, some patients have increased serum IgE, allergen tests help to find possible allergens, patch test helps to diagnose contact dermatitis, fungal tests can identify superficial fungal disease, scabies test can help to exclude scabies, serum immune Globulin test can help identify congenital diseases with eczema dermatitis lesions, bacterial culture of skin lesions can help diagnose secondary bacterial infections, etc., and skin histopathological examination should be performed when necessary. Fourth, the diagnosis and differential diagnosis of eczema is mainly based on clinical manifestations, combined with the necessary laboratory tests or histopathological examination. Special types of eczema are diagnosed according to clinical characteristics, such as dry eczema, self-sensitivity dermatitis, coin-shaped eczema, etc.; non-specific cases can be diagnosed according to clinical sites, such as hand eczema, calf eczema, perianal eczema, breast eczema, scrotal eczema, ear eczema, eyelid eczema, etc.; generalized eczema refers to eczema that occurs simultaneously in multiple sites. The severity of eczema can be scored according to its size and the characteristics of the rash. The following diseases should be differentiated: ① Other dermatitis with specific etiology and clinical manifestations should be differentiated, such as atopic dermatitis, contact dermatitis, seborrheic dermatitis, bruising dermatitis, neurodermatitis, etc.; ② Diseases with eczema-like manifestations should be differentiated, such as superficial fungal disease, scabies, polymorphic heliotrope, eosinophilic syndrome, pellagra, and cutaneous lymphoma; ③ Rare congenital diseases with eczema-like ③ Differentiate from rare congenital diseases with eczema-like lesions, such as Wiskott-Aldrich syndrome, selective IgA deficiency, high IgE recurrent infection syndrome, etc. V. Treatment: The main goal is to control symptoms, reduce recurrence, and improve the quality of life of patients. Treatment should be considered as a whole, taking into account both the immediate and long-term efficacy, with special attention to medical safety in treatment. 1, basic treatment: ① patient education: the need to explain the nature of the disease, possible regression, the impact of the disease on the health of the body, the presence of infectious, the clinical efficacy of various treatment methods and possible adverse reactions, etc., to guide patients to find and avoid common allergens and irritants in the environment, to avoid scratching and excessive washing, the environment, diet, the use of protective equipment, skin cleaning methods should also be recommended accordingly; ② Avoid triggering or aggravating factors: through detailed history taking, careful physical examination, and reasonable use of diagnostic tests, carefully search for various suspected causes and triggering or aggravating factors in order to remove the causes and treatment, such as dry eczema should treat the factors that make the skin dry, and infectious eczema should treat the primary infection, etc.; ③ Protect the skin barrier function: eczema patients have damage to the skin barrier function and are prone to secondary irritant dermatitis (3) protection of skin barrier function: eczema patients have damage to the skin barrier function and are prone to secondary irritant dermatitis, infection and allergy and aggravate the lesions, so it is important to protect the barrier function. The patient’s skin should be selected for treatment without irritation, the prevention and timely treatment of secondary infections, subacute and chronic eczema of dry skin with moisturizers. 2, local treatment: is the main means of virtual rash face treatment. According to the stage of the lesions should be selected according to the appropriate drug formulations. Acute stage without blisters, vesicles, exudate, it is recommended to use furnace glycolate lotion, glucocorticoid cream or gel; a large number of exudate should choose cold wet compress, such as 3% boric acid solution, 0, 1% berberine hydrochloride solution, 0, 1% ezacrine solution; vesicles but not much exudate can be used when the zinc oxide oil. For subacute lesions, topical zinc oxide paste and glucocorticoid cream are recommended. For chronic lesions, topical glucocorticoid ointments, creams, emulsions or tinctures are recommended, and moisturizers and keratolytic agents, such as 20%-40% urea ointment and 5%-10% salicylic acid ointment, can be used in combination. Topical glucocorticoid preparations are still the mainstay of eczema treatment. Initial treatment should be based on the nature of the lesions by choosing the appropriate strength glucocorticoid: for mild eczema, weak glucocorticoids such as hydrocortisone and dexamethasone cream are recommended; for severe hypertrophic lesions, strong glucocorticoids such as harcinexide and halometasone cream are recommended; for moderate eczema, moderate hormones such as tretinoin and mometasone furoate are recommended. Weak or medium-acting glucocorticosteroids are generally effective in pediatric patients, lesions on the face and skin folds. Strong glucocorticosteroids are generally applied continuously for no more than 2 weeks to reduce acute tolerance and adverse effects. Calcium-regulated neurophosphatase inhibitors such as tacrolimus ointment and pimecrolimus cream have therapeutic effects on eczema without the side effects of glucocorticoids, and are particularly suitable for the treatment of eczema on the head, face and inter-rub areas. Bacterial colonization and infection can often trigger or aggravate eczema, so antibacterial drugs are also an important aspect of topical treatment. A variety of topical preparations of antibacterial drugs are available, as well as a combination of glucocorticoids and antibacterial drugs. Other topical drugs such as tar, antipruritic agents, topical preparations of non-steroidal anti-inflammatory drugs, etc., can be applied according to the situation. 3. Systemic treatment: ① antihistamines: choose appropriate antihistamines to stop itching and anti-inflammation according to the patient’s condition; ② antibiotics: for those with extensive infection, it is recommended to systematically apply antibiotics for 7-10d; ③ vitamin C and calcium gluconate have certain anti-allergic effects and can be used for acute attacks or obvious itching; ④ glucocorticoids: it is generally not advocated to be used routinely. However, they can be used for patients with clear etiology and short-term elimination of etiology, such as those caused by contact factors, drug factors or self-sensitivity dermatitis; for severe edema, generalized rash, erythroderma, etc., they can also be applied short-term for rapid symptom control, but caution must be exercised to avoid systemic adverse reactions and rebound; ⑤ Immunosuppressants: they should be used with caution and the indications should be strictly controlled. It should be used only in patients with severe disease who have contraindications to the application of glucocorticosteroids, or after the short-term systemic application of glucocorticosteroids has been significantly relieved, and when glucocorticosteroids need to be reduced or discontinued. 4, physical therapy: ultraviolet therapy, including UVA1 (340-400nm) irradiation, UVA/UVB irradiation and narrow-spectrum UVB (310-315nm) irradiation, has a better effect on chronic intractable eczema. 5, Chinese medicine therapy: Chinese medicine can be internal or external treatment, should be based on the condition of evidence-based treatment. Chinese medicine extracts such as compound glycyrrhetinic acid glycosides, tretinoin polysaccharide, etc. are effective for some patients. It should be noted that herbal medicine can also lead to serious adverse reactions, such as allergic reactions, liver and kidney damage, etc. 6. Follow up and prevention: The disease is prone to recurrence and patients are advised to follow up regularly. Acute eczema patients should preferably be seen once a week after treatment, subacute patients 1-2 weeks after treatment, and chronic patients 2-4 weeks after treatment. Follow-up appointments evaluate efficacy, changes in condition, the need for further testing, and evaluation of compliance. For recurrent and persistent cases, attention should be paid to analyze the causes, which are common: ①Irritant factors: Due to the destruction of the skin barrier function, new or weak irritants, even substances that are not irritating under normal circumstances, become irritants. Note that therapeutic medication can also produce irritation; ② neglect of contact allergens: neglect of certain contact allergens in the family, occupation and hobbies; ③ cross-allergy: pay attention to the cross-allergens of allergens carefully checked; ④ secondary allergy: pay attention to avoid secondary allergy to drugs (especially adrenal glucocorticoids) and chemicals (such as rubber latex in gloves); ⑤ secondary infection: destruction of skin barrier function (5) secondary infections: destruction of skin barrier function, and application of adrenal glucocorticoids, etc., which can easily cause secondary bacterial or fungal infections; (6) unfavorable factors: sunlight, hot environment, continuous sweating, cold and dry can aggravate the condition; (7) systemic factors: such as pruritus and secondary skin infections in diabetic patients.