A review in the Open Respiratory Medicine Journal concluded that zinc lozenges may shorten the duration of common cold episodes by up to 40%.
Dr Harri Hemila of the University of Helsinki, Finland, who authored the review, said: “Controlled trials that have examined the effect of zinc lozenges on common cold symptoms have reported divergent results.
“This meta-analysis shows that a large part of the divergence can be explained by the variation in the total daily dose of zinc that the person obtained from the lozenges.”
Data from 5 trials using total daily zinc doses of less than 75 mg found no effect, but data from 3 trials using zinc acetate in daily doses of over 75 mg indicated that the mineral may reduce the duration of the cold by 42%.
Date from 5 trials using zinc salts – other than acetate – in daily doses of over 75 mg found a reduction in cold duration by 20%.
Similar results were obtained from a 2011 Cochrane review, but only if taken within a day of the onset of cold symptoms
The total economic impact of cold-related work loss is estimated to exceed $20 billion USD per year (Cochrane review). As a result, Americans spend around $2.9 billion on over-the-counter drugs (and another $400 million on prescription medicines) for symptomatic relief of cold.