An ear infection is a common cause of ear pain and discomfort. It is caused by a bacterium or virus in the middle ear, which often results from another illness such as a cold, flu, or allergy that causes congestion and swelling of the nasal passages, throat, and eustachian tubes. The eustachian tubes are a pair of narrow tubes that run from each middle ear to high in the back of the throat, behind the nasal passages. The throat end of the tubes open and close to regulate air pressure in the middle ear, refresh air in the ear, and drain normal secretions from the middle ear. Swollen eustachian tubes can become blocked, causing fluids to build up in the middle ear. This fluid can become infected and cause the symptoms of an ear infection.

Other causes of ear infections include allergies, post-nasal drainage, sinus infections, common cold viruses, and adenoid problems, which can all interfere with the eustachian tubes ability to let air pass into the middle ear. In children and infants, the eustachian tube is often too soft or immature and has a harder time staying open, making them more susceptible to ear infections.

It is important to note that an ear infection is different from having a bug or worm in the ear, which is a rare occurrence. Symptoms of having a bug in the ear include persistent ear pain, swelling, redness, itching, unexplained tingling and/or tickling sensation, suspicious buzzing, ringing in the ear, bleeding or pus draining from the ear, mild hearing loss along with the impression that the ear is clogged and muffled external sounds, and a perception of a foreign object in the ear. If the bug stays in the ear for a long time, inflammation of the ear canal can occur, and other problems that can arise from a bug in the ear include rupture of the tympanic membrane, hearing loss, and inflammation of the ear.

In summary, an ear infection is caused by a bacterium or virus in the middle ear, which often results from another illness such as a cold, flu, or allergy that causes congestion and swelling of the nasal passages, throat, and eustachian tubes. Other causes of ear infections include allergies, post-nasal drainage, sinus infections, common cold viruses, and adenoid problems.