A caveat: more than 200 viruses are known to cause the symptoms of the common cold. So echinacea’s effectiveness may depend on which virus you’re exposed to. In most of the studies volunteers were exposed to colds naturally in their ordinary environment. When the data was limited to three studies in which volunteers were directly inoculated with a single virus, echinacea still upped their chances of avoiding symptoms, but only by 18.5 percent. One such study, published in the New England Journal of Medicine in 2005, found that echinacea did no better than a placebo.
It’s also important to know that not all store brands of echinacea are reliable. In a 2004 evaulation of 19 brands, Consumer Reports found that the amount of echinacea actually present in the supplement varied considerably from brand to brand and even from bottle to bottle. The magazine’s best picks for all-around value: Spring Valley, Origin and Sundown. One more note: echinacea can cause allergic reactions, may interact badly with some common medications and should be avoided by anyone with an autoimmune disease and a handful of other illnesses. Check with your doctor before taking it.
