This list is not all inclusive, and the causes are not presented in order of likelihood. The causes of this symptom can include unlikely diseases and medications. Furthermore, the causes may vary based on age and gender of the affected person, as well as on the specific characteristics of the symptom such as quality, time course, aggravating factors, relieving factors, and associated complaints. Use the Symptom Analysis option to explore the possible explanations for an impaired sense of smell, occurring alone or in combination with other problems. The loss of smell is usually an insignificant result of nasal congestion or obstruction, but it can sometimes indicate a neurological disorder.
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.