An infection that affects the sinuses, nose, oral cavity, tonsils, throat, and larynx can be defined as upper respiratory tract infection (URTI). A wide range of bacteria and viruses can cause infections in the upper respiratory tract. Acute bronchitis, the flu, the common cold, and respiratory distress syndromes are all caused by them. Because of the similarity in causes and symptoms associated with URIs, it is often difficult to distinguish between different patient conditions. Patients without evidence of pneumonia, no other medical history that could explain the patient’s symptoms, or a history of chronic obstructive pulmonary disease (COPD), emphysema, or chronic bronchitis are considered to have upper respiratory tract infections. During a URTI, the bacterium typically invades the upper airway mucosa directly. Breathing in contaminated droplets is the most common way to contract the bacterium. First, the hair lining acts as a barrier, capturing pathogens. Second, mucus, like the hair lining, traps organisms. Third, the angle between the pharynx and nose is a barrier, preventing particles from falling into the airways. Finally, ciliated cells in the lower airways eliminate the pathogens.