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.