The human ear, nose, pharynx and larynx are located in different parts of the head and face, and on the surface they do not appear to be connected, but in fact, they are all connected to each other with the pharynx as the center. The eustachian tube, also known as the Eustachian tube, is a channel between the tympanic chamber and the nasopharynx, with one end opening in the tympanic chamber and the other in the lateral wall of the nasopharynx. The eustachian tube is the only channel for middle ear ventilation and drainage, and its main function is to guide the nasopharyngeal gas into the tympanic chamber, which is normally closed and only opens when swallowing or yawning, in order to maintain the pressure balance on both sides of the eardrum, thus ensuring the normal vibration of the eardrum. When a cold occurs, the nose becomes inflamed and secretions increase. If the pressure in the nasal cavity increases, such as inappropriate nose-blowing movements, etc., the secretions in the nasal cavity can enter the middle ear cavity via the eustachian tube, causing otitis media. Especially in children, because the eustachian tube is wide, short and straight, nasal secretions are more likely to cause otitis media via this route. In addition, the nasal mucosa, nasopharyngeal mucosa, and the lining of the eustachian tube are connected to each other. When a cold or upper respiratory tract infection occurs, these mucosa can become swollen and congested, even causing narrowing or obstruction of the eustachian tube, and inflammation can invade the middle ear along the eustachian tube, leading to otitis media. When there is an acute infection in the nasal cavity (acute rhinitis) or other diseases affecting nasal ventilation (such as chronic rhinitis, sinusitis, etc.), the use of nasal drops is beneficial to the recovery of the function of the eustachian tube, which can reduce nasal secretions and congestion, and the swelling and obstruction of the eustachian tube will also be reduced, which is conducive to the healing of otitis media. Therefore, when doctors treat otitis media, they often prescribe some drugs like nasal drops to patients.