How do we get ear infections? Why do we get earaches?

Dear Dr. Cory:

How do we get ear infections? Why do we get earaches?

Jessie Backman Morris, Minnesota

Nash Stanton Wenatchee, Washington

Dear Jessie and Nash:

Behind your eardrum is a small cavity called the middle ear. The cavity continually produces a small amount of fluid to keep the middle ear moist. Extra fluid is drained to the throat through a tiny tube called the eustachian (you-STAY-shen) tube. The eustachian tube also allows air to flow up to the middle ear, keeping air pressure equal on both sides of the eardrum.

Most ear infections get started when you get a cold or a sore throat, and the germs that are making you sick travel up the eustachian tube to your middle ear. The eustachian tube becomes swollen and blocks the flow of fluid out of the ear cavity. This buildup of fluid can be very painful, so you also get a earache. Because the infection is behind the eardrum, eardrops will not treat it. You need to see a doctor to get special medicine that goes into your bloodstream to reach the infection behind the eardrum.