Symptoms reduced in adults, but not children; bad taste, nausea are common adverse effects
MONDAY, May 7 (HealthDay News) -- Oral zinc may shorten the duration of symptoms associated with the common cold in adults, but adverse effects are common, according to a review published online May 7 in CMAJ, the journal of the Canadian Medical Association.
Michelle Science, M.D., from the Hospital for Sick Children in Toronto, and colleagues conducted a systematic literature review and meta-analysis. Randomized controlled trials comparing orally administered zinc with placebo or no treatment were included.
The researchers found 17 trials that included a total of 2,121 participants. Participants receiving zinc had a shorter duration of cold symptoms than those receiving placebo (mean difference, −1.65 days; 95 percent confidence interval [CI], −2.50 to −0.81). Zinc shortened the duration of cold symptoms in adults (mean difference, −2.63 days; 95 percent CI, −3.69 to −1.58) but had no significant effect in children (mean difference, −0.26 days; 95 percent CI, −0.78 to 0.25). Heterogeneity was high in all subgroup analyses. Compared to the placebo group, the risk ratio (RR) for any adverse event for those in the zinc group was 1.24 (95 percent CI, 1.05 to 1.46), and included bad taste (RR, 1.65; 95 percent CI, 1.27 to 2.16) and nausea (RR, 1.64; 95 percent CI, 1.19 to 2.27).
"The results of our meta-analysis showed that oral zinc formulations may shorten the duration of symptoms of the common cold," the authors write.
All studies included in the review were funded by the pharmaceutical industry.