JAMA : the journal of the American Medical Association
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Are Echinacea products associated with a reduced incidence and a shorter duration of common colds compared with placebo? ⋯ Individual prophylaxis trials show no association with prevention of the common cold, but exploratory meta-analysis suggests that Echinacea products may be associated with a small reduction in cold incidence. In treatment trials, there was no association of Echinacea products with a shorter duration of colds.