Ear Infections | Overview

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How does the ear work?

A tube called the eustachian (say: "you-stay-shee-an") tube connects the middle ear with the back of the nose. Normally this tube lets fluid drain out of the middle ear. If bacteria or viruses infect the lining of the eustachian tube, the tube gets swollen and fills with thick mucus. This keeps the ear from draining normally. Sometimes bacteria can grow in the fluid, increasing pressure in the middle ear behind a bulging eardrum and causing pain.

The vibration of the eardrum causes the tiny bones in the ear to move. This movement sends the sound waves to the inner ear.

What causes earaches?

A tube called the eustachian (say: "you-stay-shun") tube connects the middle ear with the back of the nose. Normally this tube lets fluid drain out of the middle ear. If bacteria or viruses infect the lining of the eustachian tube, the tube gets swollen and fills with thick mucus. This keeps fluid in the ear from draining normally. Bacteria can grow in the fluid, increasing pressure behind the eardrum and causing pain.

The eustachian tubes can also become blocked because of allergies, a cold, or other infection. In other cases, the adenoids (glands near the ear) become enlarged and block the eustachian tubes. When the tubes are blocked, even if there is no infection, air in the middle ear space is gradually absorbed and this creates a vacuum or negative middle ear pressure. This negative pressure also often creates an achy discomfort, and can lead to fluid (effusion) in the middle ear and reduced hearing. Doctors call this whole pattern “eustachian tube dysfunction.” Learn more about eustachian tube dysfunction here.

Acute ear infections usually clear up within 1 or 2 weeks. Sometimes, ear infections last longer and become chronic. After an infection, fluid may stay in the middle ear. This may lead to more infections and hearing loss.

Why are earaches so common in children?

Ear infections may be more common in children because their eustachian tubes are shorter and more narrow than those of adults. Most children will have at least 1 ear infection by their third birthday.

What are the types of ear infections?

Otitis media is a term that refers to an inflammation of the middle ear without indicating a specific cause of the condition. Conditions affecting the middle ear include acute otitis media and otitis media with effusion. Learn more about otitis media with effusion here.

Another type of ear infection involves the outer ear and ear canal. Swimmer’s ear or otitis externa is caused by water irritating the skin inside the ear. Learn more about otitis externa (swimmer’s ear) here.

Bibliography

See a list of resources used in the development of this information.

Written by familydoctor.org editorial staff

Reviewed/Updated: 05/16
Created: 01/99

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