Since the first randomized, double- blind trial was published in 1983, zinc has been promoted as a means to lesson the duration and severity of the common cold. The lozenge form of zinc is used most often for the purpose of treating the common cold because zinc is best absorbed when it dissolves slowly and is able to coat the mouth and throat, where cold viruses thrive.5,11 However, subsequent studies have had contradictory findings, likely due to differences in the form of zinc, the dosage, and how long it was used in the studies.2 A more recent (2011) Cochrane review of 13 clinical trials3 found that zinc lozenges did not prevent colds, but if taken within a day of the onset of cold symptoms, the lozenges could reduce the severity of the cold. A variety of zinc products are available over the counter in the form of lozenges, supplements, and syrups for treating the common cold; research has yet to shed light on which form most effective.
- Eby GA, Davis DR, Halcomb WW. Reduction in duration of common colds by zinc gluconate lozenges in a double-blind study. Antimicrob Agents Chemother. 1984;25:20–24.
- Jackson JL, Lesho E, Peterson C. Zinc and the common cold: a meta-analysis revisited. J Nutr. 2000;130 (5 suppl):1512S–1515S.
- Singh M, Das RR. Zinc for the common cold. Cochrane Database Syst Rev. 2011;(2):CD001364.