Echinacea
A systematic review by the Cochrane Collaboration, last updated in 2006, examines sixteen randomized controlled trials studying various echinacea preparations for prevention and treatment of the common cold. Echinacea showed no benefit over placebo for prevention. Evidence for treatment was inconsistent. Reported side effects were rare.
A 2007 meta-analyses concludes that there is some evidence that echinacea may reduce either the duration or severity of the common cold, but results are not consistent.
Use of echinacea preparations is not currently recommended.
Read more about this topic: Alternative Treatments Used For The Common Cold