But what exactly is fluid in the ear? Fluid in the ear means a buildup of mucus, or fluid, behind the eardrum. A healthy middle ear is filled with air, not fluid. Having fluid in there can be ...

When you have a cold, inflammation and mucus can cause problems with the eustachian tube. This tube connects the middle ear (located behind the eardrum) to the back of the throat and nose.

This mucus can become infected and cause ear ... can potentially impair hearing due to the fluid build-up behind the eardrum.