Current Research Shows No Causal Link Between Zinc Gluconate and Loss of Smell

The safety of zinc cold remedies is well documented. No serious adverse events related to their use have been reported in any clinical trial. In studies of lozenges and nasal sprays, the most commonly reported side effects were headache, dry mouth and/or dry throat, taste alteration, nasal irritation or burning, and gastrointestinal disturbances (such as nausea and constipation).

In randomized placebo-controlled clinical trials focusing exclusively on intranasal zinc gluconate gel, the overall incidence of side effects also was low, with no statistically significant difference between the adverse event rates for the treated and placebo subsets. ^{1 2}

In no clinical trial of intranasal zinc gluconate gel products has there been a single report of lost or diminished olfactory function (sense of smell). Nevertheless, some authors have speculated that there is a link between the use of these products and anecdotal reports of anosmia. Two authors based their conclusions on findings from 1930’s studies evaluating the nasal administration of a concentrated solution of zinc sulfate for polio prevention. ³

The courts have repeatedly rejected this extrapolation as unscientific, unsupported and unreliable, given that zinc gluconate and zinc sulfate are different compounds with different constituents, molecular weights, disassociation constants and materially different levels of zinc.

Zinc nasal gel for the treatment of common cold symptoms: A double-blind, placebo-controlled trial.

Effect of zincum gluconicum nasal gel on the duration and symptom severity of the common cold in otherwise healthy adults.