In the process of eczema, a variety of secondary factors will gradually replace the original allergens, becoming the main factors contributing to the deterioration of the disease and the development of chronic. 1, scratching: scratching caused by itchy epidermis rubbed, aggravating inflammation, and inflammation stimulates the nerves, enhancing the itch, such as the formation of a vicious circle. In addition, scratching causes skin damage, increasing the chance of invasion of bacteria and allergens. 2. Sweat retention: The secondary skin inflammation affects the sweat gland mouth and ducts. If the temperature rises or mental stimulation increases sweat secretion, coupled with a large number of duct obstructions, it will cause sweat retention, leading to intense pruritus and persistent inflammation. 3, secondary infection: persistent inflammation causes changes in the skin of the affected area, the normal skin surface of the genus Micrococcus disappears and is replaced by coagulase-positive Staphylococcus aureus, sometimes Streptococcus hemolyticus or Pseudomonas aeruginosa. 4, loss of barrier function: acute inflammation of the skin, the stratum corneum or epidermis partly peeled off, the barrier is destroyed, skin permeability greatly increased, some of the original irritation is not easy to sensitize the drug penetration into the skin, resulting in irritation, burning sensation or cause allergies.