What is Loss of Smell (Anosmia) and How Common Is It?

Anosmia is the lack of olfaction (which is the ability to perceive smells). It can be either temporary or permanent. Anosmia is to smell what blindness is to sight, or deafness is to hearing. Anosmics cannot detect scents of any kind. The National Institutes of Health estimates approximately 2.5 million American adults suffer from some degree of loss of smell, but most experts believe the true number is much higher and recent studies support that view.

A related term, hyposmia , refers to a decrease in the ability to smell, while hyperosmia refers to an increased ability to smell. Some people may be anosmic for one particular odor. This is called “specific anosmia” and may be genetically based. Ageusia, a companion word, refers to a lack of taste sensation. It should be noted that sense of smell does not affect the sense of taste. In fact, even with complete anosmia, patients retain the ability to distinguish salt, sour, sweet and bitter – humans’ only taste sensations. Without a sense of smell, however, the ability to detect and distinguish flavors is affected.

Someone who is born without a sense of smell has congenital anosmia. This is rare and can be associated with other abnormalities, such as cryptorchidism, midline craniofacial defects, deafness and renal agenesis. ¹