Bronchitis can be caused by microbial infection, physical or chemical irritation, or allergies. Bronchitis caused by microbial infections may be contagious, while bronchitis caused by other causes is generally not contagious. Bronchitis due to viral infections, such as influenza virus and neocoronavirus, may be airborne or contact transmitted, leading to the induction of the disease in normal people. Most bronchitis caused by bacterial infections are not contagious, but bronchitis caused by specific bacteria such as Mycobacterium tuberculosis, for example, can be spread through droplets and is somewhat contagious. In addition to this, bronchitis can be caused by damage to the mucous membranes of the bronchial tubes caused by exposure to cold air or irritating gases. Or bronchitis is caused by an allergic reaction of the bronchial mucosa caused by inhalation of pollen, fungal spores, animal fur and other allergens. These conditions are not contagious. Bronchitis patients should go to the hospital in time to check the specific cause of the disease and choose the appropriate method of treatment, try to avoid causing the spread of the disease.