Pediatric bronchitis is an infection of the bronchial mucosa caused by various pathogens. Clinical presentations commonly begin with symptoms of upper respiratory infection such as nasal congestion, sneezing, runny nose, or low-grade fever, followed by coughing as the main symptom. Initially, the cough is dry, later accompanied by phlegm. Symptoms can be more severe in infants and young children, often including fever, vomiting, and diarrhea, generally without systemic symptoms. Auscultation of the lungs reveals coarse breath sounds, with fixed and scattered dry rales, and medium to coarse moist rales. Infants and young children often have difficulty expelling phlegm, which may be audible in the throat and lungs as a rattling sound. If the infant or young child has wheezing bronchitis accompanied by eczema, or other allergic histories, they may develop pronounced symptoms of difficulty breathing, and may even progress to asthma.