The etiology and pathogenesis of eczema are quite complex, involving a variety of factors both internal and external. Allergic reactions play an important role in the pathogenesis of eczema, and eczema is a late-onset allergic reaction. The disease often occurs in individuals with allergic qualities. Anyone with this quality is prone to allergic reactions to various allergenic substances inside and outside the body, such as proteins in food, especially fish, shrimp, eggs and cow’s milk, as well as chemicals, plants, animal leather and feathers, parasites in the intestines, foci of infection, etc. Some even physical stimuli such as sunlight, wind and heat, and cold can induce eczema. In addition, the occurrence of eczema may also be related to neurological dysfunction, endocrine disorders, indigestion, intestinal diseases, metabolic abnormalities, etc. In short, the onset of eczema is often the result of many factors interacting with each other. Since eczema has more rash forms and the course of the disease is often recurrent and stubborn, it is often difficult for lay people to recognize eczema, so let’s briefly introduce it first. Now, eczema is considered a general term for a class of inflammatory skin diseases caused by a variety of internal and external factors. The pathogenesis of this disease is complex, and the exact cause is often unclear. It has the following clinical features: polymorphic: erythema, dense corn papules, papules, surface vesicles, oozing, crusting, thickening, lichenification and chapping, etc. Again, one form is predominant, sometimes several forms are mixed, like beads in a kaleidoscope, constantly combining. Recurrence: It means that the disease can be cured, but then it often recurs, either because of exposure to certain substances, inhalation of certain dust impurities, ingestion of certain foods; or it recurs in a certain season. This is due to the increased sensitivity of the patient and the multi-source nature of the allergenic substances. Persistent: This refers to eczema that does not respond well to treatment and is unsatisfactory with multiple treatments. Even now, with the introduction of topical corticosteroid creams, it can be effectively “suppressed”, but once the medication is discontinued, the eczema resurfaces and changes from acute to chronic in a repetitive manner. Symmetry: The rash is mostly issued in batches and symmetrically on the trunk and extremities, and the rash is basically symmetrical and very similar in appearance. Pruritus: Regardless of the site of occurrence, all phases of eczema are intensely itchy, which is the most prominent and torturous symptom. The pathological histology of eczema is characterized by plasma exudation that collects between epidermal cells and forms spongy and small blisters. This is a microscopic reflection of the essential characteristic of eczema, which is “wetness”. What is the incidence of eczema? There are many cases of ringworm in dermatology clinics, but eczema is more common than ringworm. According to current statistics, eczema can account for up to 85% of daily outpatient visits. A survey in the United States showed a prevalence of 1.8% for all types of eczema. It is one of the first skin diseases to develop in humans. Eczema occurs in infancy; it can occur from birth to death; and it is a common disease at any age. Is eczema hereditary? Eczema is the result of the interaction of a variety of internal and external factors, allergic qualities are the main factor in the development of allergy, allergic qualities and genetics have a significant correlation, so that eczema can be inherited. It has been found that individuals with a family or personal history of allergic qualities are susceptible to allergic disorders such as asthma, allergic rhinitis, eczema, and urticaria. According to statistics, if both parents have eczema, the risk of their children developing eczema is greater than 70%, and if only one parent has eczema, the risk is greater than 30%. Is eczema contagious? So far there is no evidence that eczema is contagious to others. The medical community has conducted numerous experiments to prove that Staphylococcus aureus is a component of the normal human skin flora, and that eczema patients can have significant migration of Staphylococcus aureus in their lesions.