Bronchitis is a common disease clinically, typically presenting symptoms such as coughing, expectorating phlegm, chest tightness, etc. Whether this disease is contagious or not depends on specific analysis. If bronchitis is caused by physical, chemical factors, or allergies, it is not contagious. However, if it is caused by pathogenic microorganisms, it could be contagious. For example, bronchitis caused by influenza virus or Mycoplasma pneumoniae infection is infectious, and isolation should be considered.