There are many reasons for sneezing, which are commonly seen in the following aspects: 1. Physiological reaction: when the nasal cavity is stimulated by special odors in the air, dust, cold air and other factors, there can be a protective sneezing reaction; 2. Pathological reaction: common viral colds are the most common, which mostly occurs in winter and spring seasons, and the clinical manifestations are usually based on the symptoms of the nose, and the patient can have sneezing, nasal congestion, runny nose, and in addition to the symptoms of sore throat, dry throat and cough. Sore throat, dry throat, cough and other symptoms, a small number of patients can appear fever, most of the patients in the course of a week or so to heal; 3, allergic rhinitis: if often itchy nose, runny nose, sneezing, the patient is mostly in contact with allergic substances in the allergic reaction, such as contact with animal fur, pollen, the manifestation of itching in the nose, nasal congestion on both sides, paroxysmal bunches of sneezing, and snot is mostly clear water-like.