Background: Zinc is an essential mineral. Beneficial zinc absorption takes place via enteral, parenteral, or cutaneous routes. However, direct application to the olfactory epithelium has been reported to cause loss of smell. Recently, intranasal zinc gluconate has been recommended as a treatment for the common cold. Severe posttreatment hyposmia and anosmia have been observed.
Methods: The case report of a typical patient is presented and analyzed in detail, followed by a series of patients with severe hyposmia or anosmia after the use of intranasal zinc gluconate.
Results: Although interindividual variation in drug response and drug effect is apparent, the severe hyposmia or anosmia appears to be long lasting or permanent in some cases. The mechanism of olfactory loss is thought to be the direct action of the divalent zinc ion on the olfactory receptor cell.
Conclusions: Zinc ions are toxic to olfactory epithelium. Reports of severe hyposmia with parosmia or anosmia have occurred after intranasal use of zinc gluconate.