Allergic rhinitis is a multifactorial disease triggered by the interaction of genes and the environment. Risk factors for allergic rhinitis may exist in all age groups. 1. Genetic factors Patients with allergic rhinitis have an atopic constitution and usually show familial aggregation, and certain genes have been found to be associated with allergic rhinitis. 2, allergen exposure Allergens are antigens that induce specific IgE antibodies and react with them. They are mostly derived from animals, plants, insects, fungi or occupational substances. Their composition is proteins or glycoproteins and very rarely polysaccharides. Allergens are mainly divided into inhalant allergens and food allergens. Inhaled allergens are the main cause of allergic rhinitis. (1) Mites The most important mites in subtropical and tropical areas are house dust mites and dust mites. House dust mites feed on human dander and live mainly in mattresses, bed bases, pillows, carpets, furniture and plush toys. They reproduce fastest in hot (above 20°C) and humid (>80% relative humidity) environments. House dust mite allergens are contained in their excrement particles, which are exposed to the air and can be quickly re-deposited when the contaminated fabric is touched. The concentration of mite allergens in the air is associated with the development of allergic rhinitis. (2) Pollen Wind-borne pollen can affect people hundreds of kilometers away from the pollen source because of its large dispersion and ability to travel long distances. Insect-borne pollen can only be sensitized by direct contact, such as agronomists and florists. The allergenic capacity of pollen varies with season, geographic location, temperature and plant species. Most pollen sensitizers will suffer from conjunctivitis. (3) Animal dander Animal dander and secretions carry allergens. Cat and dog allergens are widely present in house dust and furniture decorations. (4) Fungal allergens Mold releases allergenic spores into the indoor and outdoor environment and grows rapidly in hot and humid environments. (5) Cockroach allergens Allergens are found in their feces and carapace, and the particles are large and do not spread in the air. (6) Food allergens Food allergic reactions are rare when allergic rhinitis is not accompanied by other systemic symptoms. On the other hand, food allergic reactions are common in cases where the patient has multiple organ involvement. In infants, most are caused by milk and soy; in adults common food allergens include: peanuts, nuts, fish, eggs, milk soy, apples, pears, etc.