Our ears are connected to the nasopharynx by a tube that is medically known as the eustachian tube. This tube opens when we chew, yawn, or swallow, so that gas can enter the ear through the eustachian tube, thus maintaining the balance between the air pressure inside the ear and the outside world. If this tube is blocked for various reasons, the gas inside the ear will be absorbed and the outside air pressure will press the eardrum inward, resulting in symptoms such as tinnitus, ear congestion and hearing loss. After a person catches a cold, acute inflammation of the nasal cavity and pharynx (such as acute rhinitis, acute sinusitis, acute nasopharyngitis, acute pharyngitis, acute tonsillitis) causes edema and inflammation of the mucous membrane at the mouth of the eustachian tube located on the side wall of the nasopharynx. The inflammation can also spread along the eustachian tube to the ear, causing pathogenic bacteria to invade the middle ear and cause acute otitis media, which can lead to ear pain, fever and other symptoms. To prevent this disease from occurring, you should prevent colds in general. If you have a cold, you should treat it promptly, contract the mucous membrane of the nasal cavity with ephedrine-like drugs to facilitate the discharge of nasal secretions, and prevent you from blowing your nose hard.