Chronic otitis media is usually caused by eustachian tube dysfunction but may also result from a hole (perforation) in the eardrum that failed to heal after trauma or an acute infection of the middle ear. It can also result in a noncancerous (benign) growth of white skinlike material (cholesteatoma). People may have a perforation without ever having any symptoms, but sometimes a chronic bacterial infection develops.

Chronic otitis media may flare up after an infection of the nose and throat, such as the common cold, or after water enters the middle ear while bathing or swimming. Usually, flare-ups result in a painless discharge of pus, which may have a very foul smell, from the ear. Persistent flare-ups may result in the formation of protruding growths called polyps, which extend from the middle ear through the perforation and into the ear canal. Persistent infection can destroy parts of the ossicles—the small bones in the middle ear that connect the eardrum to the inner ear and conduct sounds from the outer ear to the inner ear—causing conductive hearing loss (see see Causes). Other serious complications include inflammation of the inner ear, facial paralysis, and brain infections. Some people with chronic otitis media develop a cholesteatoma in the middle ear. A cholesteatoma, which destroys bone, greatly increases the likelihood of other serious complications. A doctor diagnoses chronic otitis media when seeing pus or skinlike material accumulating in a hole or in a pocket in the eardrum that often drains.