Acute Otitis Media (AOM): This is the most common cause of unilateral ear infection, especially in children. It is characterized by inflammation of the middle ear, often due to bacterial infection, and presents with symptoms such as ear pain, fever, and hearing loss.

Otitis Externa: An infection of the outer ear canal, often caused by bacterial or fungal pathogens. It is common in swimmers or individuals who insert objects into their ears, leading to symptoms like itching, redness, and discharge.
Eustachian Tube Dysfunction: This condition affects the tube that connects the middle ear to the back of the nose and throat, leading to problems with ear pressure regulation. It can cause a feeling of fullness in the ear and hearing loss.
Middle Ear Effusion: Fluid accumulation in the middle ear without signs of acute infection, which can follow an episode of AOM or be due to Eustachian tube dysfunction.

Mastoiditis: A serious infection of the mastoid bone, located behind the ear. It can be a complication of untreated or inadequately treated AOM and requires prompt medical attention to prevent serious complications.
Petrous Apicitis: A rare but serious infection of the petrous part of the temporal bone, which can lead to severe complications if not recognized and treated promptly.
Labyrinthitis: An inner ear infection that can cause vertigo, hearing loss, and tinnitus. It requires early diagnosis and treatment to prevent permanent damage.

Relapsing Polychondritis: A rare autoimmune disorder that can cause inflammation of the cartilage in the ear, leading to ear pain, redness, and swelling.
Ear Canal Cholesteatoma: A type of skin cyst in the ear canal that can cause infection and damage to the surrounding bone and tissue.
Necrotizing Otitis Externa: A severe infection of the outer ear that can spread to the skull base and is more common in diabetic or immunocompromised patients.