Otitis media is the inflammation of the space behind the eardrum called the middle ear. Bacteria or more commonly a virus may cause this infection. Otitis media may also be caused by the presence of uninfected fluid. If there is redness of the ear drum there may be an infection present – this is called acute otitis media. If you have an acute otitis media you may be given antibiotics to kill the bacteria. If there is fluid behind the drum without any redness or infection - this is called otitis media with effusion. Effusion is another word for fluid. In this case, the fluid does not cause ear pain and typically goes away on its own. Antibiotics are not effective for non-infected effusions.