How common are inner ear infections in adults?

Ear infections are common in infants and children, and occur less frequently in adults, according to MedlinePlus. Males, individuals who live in households with smoking, and individuals with poor immune systems are more prone to ear infections.

Recurrent ear infections are more common in individuals with abnormalities of the palate; individuals with chronic respiratory illnesses, such as asthma and cystic fibrosis; and individuals with a family history of chronic ear infections, explains WebMD. Ear infections are caused by bacteria that gather when the ventilating function of the eustachian tube is impaired, often due to allergies, post nasal drainage and sinus infections.