Hay fever (pollinosis) is a series of lesions caused by sensitization of sensitive patients to pollen allergens, mainly manifesting as cicatricial inflammation of the respiratory tract and eyes, and occasionally causing lesions of the skin or other organs. [Epidemiology] In most areas, the incidence of hay fever has two annual peaks, with the spring peak occurring from April to June each year, mostly caused by tree pollen. The peak in autumn is usually in August to September and is mostly caused by weed pollen. The peak incidence varies with latitude, generally the higher the latitude, the more delayed the incidence season. Affected by climatic conditions, generally in the plant growth period, high temperatures, adequate rainfall, the early maturation of pollen, the onset of the season can be earlier. In the pollen dispersal season, dry climate and strong wind are conducive to pollen dispersal, which can make the peak of hay fever earlier. However, in the same region, the onset of the same hay fever is relatively fixed, and the difference between years is generally no more than a few days, so that patients can predict their onset date fairly accurately. The spring peak of hay fever onset in China begins in northern China in mid-March and tapers off in May. The main allergenic pollen is elm, poplar and willow pollen. The number of patients at this peak is not too many, and the symptoms are generally not too heavy. The fall peak in northern China begins in late July and gradually eases by the end of September, with symptoms generally disappearing by early October. This peak is caused by herbaceous pollen, which not only has more patients, but also has heavy symptoms. The majority of the main allergenic pollen is artemisia, ragweed, lawn grass, castor, etc.. In the southern region of China, in addition to the above pollen, sycamore, wildflowers, wood sorrel pollen, etc. also occupy a certain proportion. Since a large area of ragweed was found growing in the Shenyang area of China in the 1980s, it has rapidly spread to most provinces and cities in China. Among all hay fever patients, up to 82% are caused by ragweed pollen, and its peak incidence is in August every year; the incidence rate of the population can be as high as 15% during the epidemic season. [Pollen is the male organ of the plant and is spread mainly by wind and insects. The wind-borne pollinators are called wind-borne flowers, and the insect-borne pollinators are called insect-borne flowers. Wind-borne flowers are the main cause of allergies. The composition of pollen is extremely complex, containing about 25% water, but also polysaccharides, fats, proteins and peptides. All of these components can cause allergy, but the most important allergenic antigen component is protein. After exposure to pollen, the sensitized mast cells of the eye, nose, or bronchial mucosa become desaturated and release inflammatory mediators such as histamine, allergic slow-reacting substances, and allergic eosinophil chemotactic factors, which can cause a series of clinical symptoms. [Histamine causes capillary dilation and increased permeability. The nasal mucosa may be grayish-blue, due to capillary dilation and swelling, or pale, mainly due to inflammatory exudation and tissue edema. Cupulocytosis and epithelial cell expansion. Bronchial smooth muscle contraction causes asthma symptoms. Local tissue and sputum eosinophilia. There may be conjunctival congestion, edema, itchy eyes and lacrimation. [Clinical manifestations] Generally, it is more common in young people. It takes at least two years for pollen sensitization to occur, so hay fever rarely occurs in infants and children. The symptoms of hay fever are mainly manifested in the nose, eyes and bronchial tubes. I. Nasal symptoms: Nasal symptoms are the most common. Nasal mucous membrane edema, nasal itching and sneezing caused by stimulation of sensory nerves are the most common symptoms. Due to the intense nasal itching, patients often rub their noses with their hands continuously; sneezing episodes often last for dozens of consecutive days. Nasal secretions increase a lot and flow out after continuous sneezing. In severe cases, the flow of nasal secretions does not stop throughout the day during the onset season, and patients often describe having to wipe their noses with dozens of handkerchiefs or rolls of toilet paper a day. Nasal secretions are usually pulpy or mucous in nature. Due to the irritation of the secretion, the nasal vestibule or upper lip is often red and swollen, or even eroded. Hay fever is rarely secondary to infection and rarely causes hyposmia. Second, eye symptoms: more than half of the patients have symptoms such as itchy eyes and tearing, which are the result of allergic conjunctivitis and mucous membrane edema of nasolacrimal duct. Third, airway symptoms: about 8% to 14% of patients have concurrent asthma. Asthma is also seasonal, it occurs mostly several years after the onset of rhinitis, but can also occur simultaneously with nasal and ocular symptoms. Oral allergy syndrome: Oral allergy syndrome (OAS) refers to IgE-mediated local reactions in the mucous membrane of the mouth or pharynx within minutes after eating certain foods, such as itching and swelling of the lips, tongue, soft palate and throat, and the symptoms disappear quickly, rarely involving other organs. OAS mostly occurs in patients with hay fever. Foreign literature reports: about 35% of patients allergic to pollen are also allergic to fresh vegetables and fruits. [Laboratory tests] I. In vivo tests (a) Specific skin test for pollen antigens: Suspected allergenic pollen, directly applied to the patient’s skin, or subcutaneous inoculation intradermal test method. The allergic patient may have local skin redness, itching, papules, oozing and other manifestations. (ii) Conjunctival test: Using different concentrations of pollen infusion drops into the conjunctiva of one side of the patient’s eye, and the opposite eye only into the lysate used for antigen extraction as a blank control, the local reaction of the conjunctiva after the drops is observed to determine the patient’s sensitivity to pollen. Those with positive conjunctival test showed symptoms such as bulbar conjunctival congestion, lacrimation and itchy eyes. Heavy cases may also have eyelid skin redness, swelling, rash and other manifestations. (c) Nasal mucosa excitation test: A small amount of the tested pollen antigen is placed into one side of the patient’s nasal cavity. If the patient is allergic to the pollen, typical hay fever attack symptoms will appear within a few minutes after the pollen is placed; in a few patients, asthma may be induced. (4) Bronchial excitation test: The patient’s asthma symptoms, pulmonary signs and lung function changes are observed by quantitative intratracheal drops or aerosol inhalation with an infusion of suspected allergenic pollen, which can determine whether the patient is allergic to the pollen and the degree of allergy. In vitro test (a) Measurement of serum specific IgE and IgE in nasal secretion: radioallergen adsorption test (RAST) or enzyme-labeled allergen adsorption test (ELISA) can be used to detect. (B) Eosinophil count in nasal secretions: Eosinophils are significantly increased in nasal secretions of hay fever patients. (iii) Histamine, kinin, leukotriene detection in nasal secretions, and histamine release from antigen-induced leukocytes. [Diagnosis and differential diagnosis] During the season of hay fever, the diagnosis of hay fever can be clarified based on typical medical history and various examinations, and effective anti-allergic treatment measures; attention should be paid to the differentiation from influenza and chronic rhinitis, etc. [Treatment] I. Avoidance of pollen exposure: The methods to avoid pollen exposure include easy avoidance and in situ avoidance: easy avoidance means that the patient temporarily moves to an area with less allergenic pollen or no such allergenic plants during the onset season, or permanently moves to an area without such pollen. In situ avoidance means that without shifting the area, less outdoor activities, less excursions or less dense vegetation growth during the onset of hay fever season, and do not open windows and drive into the wind; it is advisable to move to the upper floors of high-rise buildings, and place air filters in the workplace or bedroom, and continuously circulate and filter the indoor air with electrostatic adsorption or activated carbon adsorption filter membrane to minimize the pollen content in the air of the living environment. Second, antihistamine drugs: Xantamine, Xismin, Keminan, Tefenadin and other oral, used for symptomatic treatment of seasonal pollen allergic reactions have a certain effect. Corticosteroids: Only the onset time is used, and corticosteroid preparations with fewer side effects are chosen. The corresponding treatment can be given according to the patient’s specific condition, such as rhinitis, asthma, conjunctivitis and skin allergy all have different treatment plans, and different treatment plans are given by the doctor according to the patient’s condition. Mast cell membrane protectors: such as sodium cromoglycate endotracheal or intranasal aerosol inhalation, 20 mg each time, 3 times a day. Ketotifen orally, 1mg per dose, twice daily. Immunotherapy: After various in vivo or in vitro specific tests, it is confirmed that the patient has an allergic reaction to a certain pollen, and the patient has been ill for more than 2 months, desensitization of the allergenic pollen can be considered according to the patient’s allergenic pollen condition and medical conditions, in order to improve the patient’s adaptability or tolerance to the allergenic pollen. The method is to use the pollen to which the patient is allergic to make allergen leachate for the patient to inject subcutaneously repeatedly, from small to large doses and from dilute to concentrated. Until the patient can tolerate larger doses without allergic reactions.