The middle ear is the space behind the eardrum, which is connected to the back of the throat by a passageway called the Eustachian tube. Middle ear infections, also called otitis media, can occur when congestion from an allergy or cold blocks the Eustachian tube. Fluid and pressure build up, so bacteria or viruses that have traveled up the Eustachian tube into the middle ear can multiply and cause an ear infection.
Middle ear infections are the most common illness that brings children to a pediatrician and the most common cause of hearing loss in children. Middle ear infections can also cause a hole (perforation) in the eardrum or spread to nearby areas, such as the mastoid bone. Adults also can get middle ear infections.
Children in day care have an increased risk of middle ear infections. The increased exposure to other infected children increases your child's chances of getting infected.