August 2020

Is There a Difference Between Hyposmia and Anosmia?

Most patients who experience smell loss have hyposmia- a relative loss of smell. While most patients, after they lose smell function, will complain that they “cannot smell” they can indeed detect many, but not all odors and can recognize some, but not all odors. This loss of acuity causes patients to say that they have “lost their smell” and most physicians relate this to the term anosmia. However, this is not the case.

Anosmia is defined as the inability to detect or recognize any odor. It is a rare condition affecting no more than 2% of patients who experience smell loss. These patients can neither detect nor recognize any odor.

Hyposmia is defined as the decreased ability to detect or recognize any odor. It is a common condition affecting most patients who experience smell loss. These patients can detect some odors although they may not be able to describe their character. Some patients may be able to detect and recognize some odors but if they do so, it is at a much reduced intensity so that at usual levels of concentration, the patient cannot tell the character of the odor. If the concentration of the odor is increased, the patient may obtain a hint of the odor character, but not at the levels experienced prior to their loss of smell.

Reference

• See: Henkin, et al. American Journal of Otolaryngology, Head Neck Surg 2019: 2, 1070 for quantitative analyses which distinguish anosmia from hyposmia.