Is oral zinc associated with a shorter duration, decreased severity, and reduced incidence of the common cold compared with placebo ?
When initiated within 24 hours of symptom onset, oral zinc is associated with a shorter duration of the common cold in healthy people. However, there is no association between oral zinc and symptom severity, and the prevalence of adverse effects with zinc lozenges is high. Given the high heterogeneity of data, these results should be interpreted with caution. Used prophylactically, oral zinc is associated with a reduced cold incidence in children. Prophylactic use has not been studied in adults.
Das RR, Singh M. Oral Zinc for the Common Cold. JAMA. 2014;311(14):1440–1441. doi:10.1001/jama.2014.1404