Have you ever had these symptoms of nasal congestion, runny nose, sneezing and itchy nose? If so, you may now be suffering from the condition I’m about to describe – allergic rhinitis. The incidence is very high, with a global prevalence of about 20%. It means that 1 in 5 people suffer from this disease, so don’t feel bad about your disease now, because it is a common disease, only you are not very aware of it. Xiao Yong, Department of Internal Medicine, Second Affiliated Hospital of Shantou University Medical College, Shantou, China The main causes are (1) hereditary allergic constitution; (2) repeated inhalation of environmental allergens. The former is obviously familial and hereditary, and may also suffer from other allergic diseases at different stages of life, such as eczema, bronchial asthma and so on. The latter factors are many, but people generally ignore or simply do not pay attention to them, such as mites, dust, animal dander, pollen, cockroaches, etc. See, this is an important reason why your allergic rhinitis persists, because they are in your home and coexist with you every day.