What causes otitis media?

Some possibilities: An ear infection on the inner side if an eardrum is a middle ear infection (otitis media) and can start when a person gets congestion from allergies, colds, or sinusitis. Natural moisture in the middle ear then has trouble leaving the middle ear, and becomes visible liquid (can often be seen as bubbles on the inside of the eardrum). Bacteria growing in that liquid turns it cloudy with infection.

Otitis media: The middle ear space should contain air but it may become filled with fluid (mucus), which typically occurs during a cold.The mucus may then become infected by germs (bacteria or viruses). This may then lead to otitis media.