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Echinacea bottles at my local food supplement store claim that taking the pills will reduce the length and severity of symptoms experienced when infected with the common cold.

Do these claims have any basis? Is there any peer-reviewed research proving the benefits of echinacea?

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Echinacea may well be one of the next substances around the corner to be accepted as medicine proper. The evidence is not striking, but there are convincing indications. With further experimentation, we may be able to single out the active agents so as to be able to devise a test that clearly differentiates it from placebo effects.

The Cochrane Collaboration has done a meta study of 16 of the most rigorous scientific trials of echinacea and the review shows that, for treatment

a significant effect was reported in nine comparisons, a trend in one, and no difference in six.

No significant effect was shown for using Echinacea as prevention.

The reviewers conclude that

Echinacea preparations tested in clinical trials differ greatly. There is some evidence that preparations based on the aerial parts of E. purpurea might be effective for the early treatment of colds in adults but the results are not fully consistent. Beneficial effects of other Echinacea preparations, and Echinacea used for preventative purposes might exist but have not been shown in independently replicated, rigorous RCTs. * Cochrane Collaboration

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    Good link, but I disagree with the intro you typed for it; it does not reflect the outcome of the study, but is more speculation. The conclusion of the meta-research is that it is not consistent .(several recent studies find no connection at all, but as I can't seem to reach pubmed at the moment I can't link atm. might look into it later.) – Nanne Mar 4 '11 at 11:08
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    @Nanne: those are indeed my reflections, and you are at liberty to disagree :) I was trying to differentiate its current state of "there are indications, but we haven't scientifically proven this one" from "this is absolute woo woo bullshit that doesn't even make sense, don't buy into it", which I think is an essential distinction to make in skepticism. The choice of words "The evidence is not striking yet" is especially poor, I'll give you that. It implies that the evidence will come up, which of course we cannot know. – David Hedlund Mar 4 '11 at 11:20
  • agreement and acceptance of terms :) (i didn't disagree that much, as i would've added an answer myself :) – Nanne Mar 4 '11 at 11:22
  • @Nanne: bah, now I'm all bummed about the "no evidence yet"-sentence, anyway. That's such a woo woo thing to say! I'll have to remove that. – David Hedlund Mar 4 '11 at 11:54
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    In any case, the likelyhood that the pills in your store will help is very low, as even the studies are using much bigger doses than your typical pill contains. I have a bottle of pills that my mum brought. I'd have to eat 50 pills a day to come up in the levels that are recommended by herbologists. – Lennart Regebro Mar 4 '11 at 18:28

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