If you have the following symptoms: frequent sneezing, runny nose, watery eyes, itchy pharynx, nose, eyes and external ear canals, coughing, difficulty in breathing, wheezing, a mass of rubella on the skin, etc., which are relieved by the onset of winter, it is very likely that you are suffering from “hay fever”. Plant pollen is the main “culprit” that causes people’s allergies. The diameter of pollen is generally about 30 to 50 microns, and it is very easy to be inhaled into the respiratory tract and adhered to the conjunctiva of the eyes when they are scattered in the air. People with a history of pollen allergy will have an allergic reaction when they come into contact with these pollens, which is known as pollen allergy. The reason why pollen can cause human allergy is because pollen is rich in proteins, and some of the protein components are the main allergens that produce allergy. The pollens that cause allergic reactions in northern patients include corn pollen, sunflower pollen, Artemisia pollen, ragweed pollen and grass pollen. How to prevent pollen allergy? Usually try to reduce the high protein, high calorie diet, less consumption of refined food. People with a history of allergy, such as allergic asthma, allergic rhinitis, urticaria or atopic dermatitis, wet diagnosis of this kind of patients, as little as possible to go to the flowers and plants, trees and lush places, and do not just go to smell the flowers and grasses; go out on a picnic the best to wear goggles, hats, masks and wear long-sleeved clothing, try to avoid direct contact with the pollen, take fast-acting anti-allergy drugs, if the skin itchy, fever, cough, shortness of breath, should quickly leave the place. In case of itchy skin, generalized fever, cough, shortness of breath, you should leave the place quickly, and once asthma symptoms appear, you should go to the hospital in time for consultation and treatment. However, it is difficult to avoid the pollen of wind-borne flowers completely. Patients with hay fever should pay attention before the blooming season, and should not wait until the onset of the disease to start treatment. Nowadays, many anti-allergy drugs not only have therapeutic effects, but also preventive effects. Therefore, in the pollen is not yet ‘rampant’ time, can be one to two weeks in advance, began to take anti-allergy drugs, but also the application of pollen blocker to reduce pollen exposure, if necessary, the application of hormone aerosol nasal spray or airway inhalation to control airway inflammation. After the fall, patients should go to the regular hospital “allergy department” (allergy department) for allergen testing and targeted immune desensitization treatment. Immunotherapy (i.e. desensitization therapy) is the main preventive tool for hay fever. The principle of immunotherapy is to inject the patient’s sensitive pollen extracts into the patient’s body in gradually increasing doses from small to large (the most commonly used immunotherapy and the more effective one is the method of subcutaneous injection), so that the patient’s body produces immunological changes, which is conducive to improving the patient’s immunity to the pollen. From years of observation at home and abroad, it has been confirmed that with proper case selection, accurate testing, high quality of allergens and correct methods, immunotherapy is quite effective. How long should immunotherapy be applied? There is no definite conclusion, but it is generally advocated that effective cases should persist for 3 years. Patients with pollen with vegetable or fruit allergy cannot be treated with immunotherapy, although food-induced symptoms cannot be treated with immunotherapy, due to the cross-reactivity between pollen and vegetables or fruits. After 1 year of immunotherapy with the pollen to which they were sensitized, not only did the hay fever symptoms improve, but a significant number of patients were able to eat the foods to which they were previously allergic.