Does echinacea work to prevent colds?

What the evidence says

Many parents wonder if echinacea, a popular herbal supplement, can stop a cold before it starts. The short answer from the best research is no, not reliably.

The Canadian Paediatric Society looked at the evidence for children and found that taking echinacea for 8 to 12 weeks as a preventive did not actually stop colds from happening. There just wasn't enough solid proof that it works in kids.

A large Cochrane review, which combines many studies to get a clearer answer, looked at echinacea in both adults and children. None of the individual studies on prevention showed a real difference between echinacea and a fake pill (placebo). When researchers combined the results afterward, there was a hint of a small benefit, but the researchers themselves said this evidence was weak.

In Canada, this matters for another reason too. Health Canada does not allow companies to put "prevents colds" on echinacea product labels, because the proof isn't there. Canadian dietitians say the same thing plainly: there isn't enough evidence that echinacea prevents colds.

An older 2007 study did find a bigger benefit, suggesting echinacea cut the odds of getting a cold by over half. But the more recent and more thorough Cochrane review looked closely at this study and felt its conclusions were too optimistic compared to the fuller body of evidence.