The loss or impairment of the sense of smell.
Some loss of smell occurs normally with aging.
In most cases, there is no obvious or immediate cause, and there is no treatment. It may occur following a viral illness. These disorders may include nasal polyps , nasal septal deformities, and nasal tumors . Other disorders that may cause a loss of the sense of smell include tumors of the head or brain, head trauma , and a wide variety of endocrine , nutritional, and nervous disorders. Many medications may change or decrease the ability to detect odors.