Pain in the root of the ear can be caused by otitis media, and oral tumors can also cause pain in the mouth and root of the ear. Otitis media, also known as “ear bottom”, is a disease that causes pain in the head and sometimes pus from the ear. Although it is not a major disease, it causes endless pain. Acute otitis media is an acute purulent inflammation of the mucous membrane of the middle ear, most commonly caused by infection of the eustachian tube. The inflammation in the pharynx and nose spreads to the eustachian tube after a cold, causing congestion and swelling of the mucosa of the pharyngeal opening and lumen of the eustachian tube, and impairment of cilia movement. The common pathogenic bacteria are mainly pneumococcus and Haemophilus influenzae, so the prevention of colds can reduce the chances of developing otitis media. 2. Incorrect methods of blowing the nose can also lead to otitis media. When swimming, avoid swallowing water in the mouth so that the water does not enter the middle ear through the nasopharynx and cause otitis media. 4. If an infant or toddler eats milk in the supine position, because the eustachian tube is relatively straight, and the lumen is short and the inner diameter is wide, milk can choke into the middle ear via the eustachian tube and cause otitis media. 5. In addition, smoking cigarettes can also cause otitis media.