Insufficient evidence for using zinc to prevent or treat colds

Compared with placebo, supplementing with zinc may lead to little or no difference in the proportion of people developing a cold over 5 days to 7 months, and little or no reduction in the mean number of colds occurring over 5 to 18 months.

Those taking zinc supplementation to treat colds had a significantly shorter duration of illness, by about 2.4 days, but the evidence was of low certainty and it was unclear whether zinc reduced global symptom severity.

No serious adverse events were noted in the studies. There was an increased risk of non-serious adverse events for those treating the common cold with zinc. The most common side effects were aberrations of taste, gastrointestinal discomfort, oropharyngeal or nasopharyngeal dryness, pain, irritation or sensitivity of the mouth or nose, and headache.