[Expert consensus on diagnosis, treatment and prevention of allergic diseases (Part Ⅰ)].

Allergic diseases are mainly type I allergic reactions mediated by IgE, which can involve multiple organs and systems of the whole body, and run through a person's whole life, with genetic susceptibility. Since most hospitals in China do not have independent allergy departments, this consensus established by multidisciplinary experts will provide guidance for the diagnosis, treatment and prevention of allergic diseases. This article is the first part of the consensus, which includes the definition of terms, epidemiology, pathogenesis, diagnosis and concomitant diseases. The prevalence of allergic diseases is increasing rapidly, and the patients are getting younger, which brings serious harm. Innate immunity, hygiene hypothesis, microecological imbalance, flora imbalance, air pollution and so on are involved in the disease. The diagnosis can be made according to typical medical history, family history, symptoms, signs, allergen detection, auxiliary examination, etc. Allergens must be tested. It is often accompanied by chronic sinusitis, secretory otitis media, snoring, chronic obstructive pulmonary disease, etc.