Intranasal zinc and anosmia: the zinc-induced anosmia syndrome

Intranasal Zinc in the Management of the Common Cold

Because zinc ions may prevent rhinovirus from attaching to and infecting cells in the nasal cavity, it has been recently hypothesized that direct application of ionic zinc to the nasal mucosa would be effective in reducing the duration of rhinovirus-associated colds. Five studies that compare intranasal zinc to placebo were identified in the medical literature. These studies provide conflicting results and are reviewed in detail. In the clinical trials that found efficacy, intranasal zinc was administered within the first 24 to 48 hours of the onset of cold symptoms. Adverse effects reported in clinical trials include nasal stinging or burning, epistaxis, headache, dry nose, dry mouth, nasal irritation, throat irritation, and nasal pain. Also of importance, case reports of intranasal zinc—induced persistent anosmia (complete loss of the sense of smell) have been reported in the literature. It is important that pharmacists inform their patients who want to use intranasal zinc of this possible complication.