Note: The study discussed here has also been covered by Mark Crislip. I wrote this before his article was published, so please forgive any repetition. I approached it from a different angle; and anyway, if something is worth saying once it’s probably worth saying twice.
Is Echinacea effective for preventing and treating the common cold or is it just a placebo? My interpretation of the evidence is that Echinacea does little or nothing for the common cold. Initial reports were favorable, but were followed by four highly-credible negative trials in major medical journals. A Cochrane systematic review was typically wishy-washy. The Natural Medicines Comprehensive Database rates it as only “possibly effective” commenting that:
Clinical studies and meta-analyses show that taking some Echinacea preparations can modestly reduce cold symptom severity and duration, possibly by about 10% to 30%; however, this level of symptom reduction might not be clinically meaningful for some patients. Several other clinical studies found no benefit from Echinacea preparations for reducing cold symptoms in adults or children…
A review on the common cold in American Family Physician stated that Echinacea is not recommended as a treatment.
I have a friend who believes in Echinacea. She says for the last several years she has taken Echinacea at the first hint of a cold, and she hasn’t developed a single cold in all that time. I told her that if that was valid evidence that it worked, I had just as valid evidence that it didn’t. For the last several years I have been careful not to take Echinacea at the first hint of a cold, and I haven’t had a single cold in all that time either. So I could claim that not taking Echinacea is an effective cold preventive! I thought my “evidence” cancelled out hers; she said we would just have to agree to disagree.
A recent study looked at the effect of belief on response to Echinacea and dummy pills. “Placebo Effects and the Common Cold: A Randomized Controlled Trial” was published by Barrett et al. in the Annals of Family Medicine. (more…)