Medical history is the cornerstone of diagnosis: For the treatment of allergic diseases, Professor Ye Shitai, the founder of the discipline of allergic reactions in China, has summarized four words: avoid, i.e., avoid contact with the substance that causes allergy; avoid, do not contact or eat the substance that causes allergy; substitute, if you are allergic to an item, find another substance to replace it; move, leave the environment that causes allergy. As you can see, finding the allergen is a prerequisite. Wang Lianglu said that there is a crossover phenomenon between allergens: there is a crossover between food, such as people who are allergic to pistachios, may be allergic to kumquats and peppers; there is a crossover between food and pollen, such as people who are allergic to artemisia, are allergic to pears, peaches, lychees, longan and other fruits; there is a crossover between pollen and different molds. Therefore identifying allergens enables patients to develop the necessary awareness of precautions. In addition, over time, some patients will have more allergens, while others have allergies that can heal themselves. For example, children who are allergic to milk and eggs have the potential to heal themselves as their gastrointestinal immunity and shielding functions improve. Therefore, allergen testing should be reviewed regularly according to the condition. At present, there are many hospitals in China that carry out allergen testing programs, but there are many irregularities, the most prominent of which is the lack of attention to medical history. Wang Lianglu pointed out that the diagnosis of allergens, the need to combine medical history and skin tests, blood test results to determine the comprehensive, which plays a decisive role is the medical history. Patients should try to give clues to the doctor, just like ranking suspects, recalling the symptoms, duration, seasonality, occasion, weather during the attack, and if it is related to food, how long after eating the attack, whether it is exercise, etc., based on which laboratory tests are conducted. The hospital once received a patient from the northeast who had a skin test at the local hospital, which resulted in more than 20 red pockets each much larger than 3 x 3 mm, and all with a red halo. So, the doctor told him that chicken, duck, fish and meat can not be eaten, rice, white flour, corn and other grains can not be eaten. As a result, this patient for several years can only take potatoes as the main food, the side dish is boiled cabbage in salt water, even dare not put soy sauce. When he came, his whole face was yellow and thin, and he was already malnourished. In fact, this patient was not allergic to any of these things, but the skin was just too reactive, creating the illusion. “So, when explaining the skin test results to patients, we usually don’t say ‘positive’ or ‘negative’, but rather that there is a reaction, no reaction, and how strong the reaction is, so as not to mislead patients.” Wang Lianglu said. In addition, blood sampling should also be screened first, check the inhalation group of allergens or food allergens two categories, to see the results and then a detailed investigation. Blood tests are also available in various combinations, such as dust mite group, tree pollen, weed pollen, pasture pollen, etc. “Asking for more than one medical history can save a lot of money for the patient, never spread a big net like testing.”