Bronchitis refers to an inflammatory lesion of the bronchial mucosa caused by biological, physical, chemical stimuli, or allergies, among other factors. Bronchitis generally occurs sporadically without epidemic tendencies. It is more common in elderly and frail patients. The primary clinical symptoms include coughing and expectoration, often occurring in cold seasons or when there are significant changes in temperature. Clinically, bronchitis can present with fever in some patients. Initially, there may be a dry cough or a small amount of sputum, which can increase in volume over time. Some patients may experience worsening coughs occasionally accompanied by bloody sputum. The cough can persist for two to three weeks. If it persists, it can develop into chronic bronchitis or pneumonia, which should be taken seriously.