The causes of hand eczema are very complex, and many internal and external environmental factors can cause hand eczema. Common causes are at least the following categories: 1, allergic contact dermatitis: caused by contact with allergens; 2, irritant contact dermatitis: caused by skin contact with water, detergents and other irritants; 3, contact urticaria: paroxysmal erythema, pruritus, and wind-blocks caused by contact with external substances; 4, sweat blister: seasonal blistering, itching, and peeling of the hands (possibly including the feet) of unknown etiology; 5, keratosis Eczema: hypertrophy, keratinization, cracking, the cause is unknown or caused by chronic irritation and allergies; 6, disciform eczema: manifested as patches of erythema, papules, water, crust; 7, atopic dermatitis: the patient has atopic dermatitis in early life, later just the hands left with lesions; 8, other: such as infection-induced eczema eight categories. The eradication of hand eczema requires finding the cause or aggravating factors. Because the hand is often exposed to a variety of physical, chemical and biological environment, and is the organ of labor, a variety of occupations require the use of hands, so patients often can not think of which external factors related to eczema, therefore, it is very difficult to find the cause.