Acute bronchitis is mostly caused by acute infection of tracheobronchial tubes, and may also be caused by chemical substances leading to tracheobronchial tubes damage, most of the cases are not serious, but in a few cases may leave sequelae or serious complications. 1. Acute tracheobronchial infections: bacterial, mycoplasma, chlamydia, viral infections and other pathogens can cause acute inflammatory lesions, through anti-infective treatment and symptomatic treatment and other treatment measures, in most cases, can be gradually recovered, the condition is not serious. However, in a few cases, it may be combined with pneumonia, and even lead to respiratory failure and other serious complications, even life-threatening. 2. Chemical bronchitis: for example, inhalation of concentrated hydrochloric acid and other chemical substances can lead to chemical tracheobronchitis, usually through symptomatic treatment, methylprednisolone and other drugs for treatment, can gradually recover, most of the disease is not serious. However, when the condition is severe, it can lead to narrowing of the airways, serious complications such as respiratory failure, or sequelae such as bronchiectasis. Therefore, acute bronchitis should be treated in a timely manner under the guidance of a doctor.