Oral zinc formulations reduced the duration of cold symptoms in adults by 2.63 days.
A number of studies have evaluated zinc for the treatment of the common cold, yielding conflicting results. Michelle Science, from The Hospital for Sick Children (Canada), and colleagues completed a systematic review and meta-analysis of 17 randomized, controlled trials that involved 2,121 participants between the ages of 1 and 65 years. The team observed that zinc shortened the duration of cold symptoms in adults (mean difference −2.63 days), but no significant effect was seen among children. The researchers observed that a reduction in the duration of cold symptoms was greater with high doses (≥75 mg versus <75 mg) of ionic zinc. In addition, the researchers reported more common instances of an adverse event – most notably bad taste and nausea, in the zinc group (as compared to placebo group). The study authors report that: “The results of our meta-analysis showed that oral zinc formulations may shorten the duration of symptoms of the common cold.”
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Michelle Science, Jennie Johnstone, Daniel E. Roth, et al. “Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials.” CMAJ, May 7, 2012.