How Much Zinc Is Needed to Cut Cold Duration, Symptoms?
While trials on the efficacy of zinc lozenges for cold symptoms have led to mixed results, a new meta-analysis has found that high-dose zinc acetate lozenges may reduce the duration of some cold symptoms by nearly 50%. These findings have been published in the journal BMC Family Practice.
A prior meta-analysis indicated that low-dose zinc lozenges (<75mg/day) had no effect on symptom duration, but high-doses (>75mg/day) reduced the duration by 42%. In this study, three randomized placebo-controlled trials were identified in which the efficacy of high-dose zinc lozenges on duration of colds and the duration of nasal discharge, nasal congestion, sneezing, scratchy throat, sore throat, hoarseness, cough, muscle ache, headache, and fever.
After pooling the data, the results showed that zinc acetate lozenges shortened the duration of nasal discharge by 34% (95% CI: 17–51%), nasal congestion by 37% (15–58%), sneezing by 22% (−1–45%), scratchy throat by 33% (8–59%), sore throat by 18% (−10–46%), hoarseness by 43% (3–83%), cough by 46% (28–64%), and muscle ache by 54% (18–89%). No difference was seen in the duration of headache and fever with zinc lozenge use; however, they were infrequently reported in the three studies and the authors could not draw any definitive conclusions for these two symptoms. Similar to the previous meta-analysis, a 42% reduction in the total cold duration was observed.
Despite the evidence that zinc lozenges are slowly dissolved in the pharyngeal region and the effects of zinc appear to be local, the researchers found no support for reduced effects of zinc lozenges in reducing the duration of nasal symptoms vs. respiratory symptoms originating in lower anatomical regions. High-dose zinc lozenges, therefore, could be a helpful treatment when initiated within 24 hours for reducing the duration of the common cold and its associated symptoms.
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