Since many substances in nature can be allergens associated with disease, it is important for the allergist to have a thorough history of the patient and a good understanding of the more common allergens in nature that can sensitize the patient before performing allergen testing. A complete medical history is important for the diagnosis and treatment of allergic diseases. A comprehensive history includes the frequency and severity of symptoms, genetic history of atopy, environmental factors (e.g., living conditions, school and leisure time environment), exposure to pets and tobacco smoke, and the relationship between exposure to allergens and environmental factors (including seasonal and diurnal variations). 1. Age of onset: may indicate whether the allergic reaction is IgE-mediated. For example, approximately 90% of patients who develop symptoms of rhinitis before the age of 10 have a positive skin test, while less than 40% of those who develop the disease after the age of 40 have a positive rate. Individuals with a history of atopic dermatitis in early childhood have an increased risk of developing allergic airway disease. Patients with asthma often have a history of allergic rhinitis in early life. People with atopic disease in one or both parents have an increased chance of having a child with the same disease. 2. Characteristics of the occurrence of symptoms: The occurrence of symptoms may be intermittent, perennial, seasonal, or perennial but seasonally aggravated. Persistent symptoms that occur in spring, summer or fall may be related to allergens such as trees, flowers, plants and seeds, respectively. Perennial symptoms may be associated with long-standing airborne allergens such as dust mites, cockroaches, fungi, and pet fur. The presence of patient exacerbations at home, school, or work suggests that allergens or factors that promote allergic reactions may be present at the respective sites. In addition, many patients, not only develop the disease when exposed to allergens, but can also be triggered by smoke and other irritants. Factors present in the environment such as temperature, humidity, and air pressure may trigger or aggravate the patient’s symptoms. 3. Atopic family history and personal medical history: Those with a single parent or two parents with allergic airway disease have an increased chance of their children developing the same disease. People with a history of atopic dermatitis in early childhood have an increased chance of developing allergic airway disease. Patients with asthma often have a history of allergic rhinitis in early life.