Echinacea

I have just the thing for that cold … Echinacea

The echinacea flower is widely believed to be an effective remedy for your sniffles and snot. Many people believe that echinacea is an immune stimulator that helps protect your body against getting colds or even fights them off. Unfortunately, there is little scientific evidence in support of echinacea fighting colds.

Studies including as many as 3,000 people have looked at whether echinacea prevents colds and whether it treats upper respiratory tract infections or colds. For neither purpose does echinacea stand up to scrutiny. The results of the studies are difficult to combine into a final set of results because they look at different parts of the plant and they use different methods for their studies. Nonetheless, an overview of the studies suggests that echinacea just does not perform as well as we would like it to.

In 2006, a Cochrane systematic review examined all of the evidence from studies of echinacea. The Cochrane systematic reviews are considered the highest-quality reviews that summarize the science of a particular subject. In sixteen studies of the herb, echinacea did no better than a sugar pill (placebo) for preventing or treating colds. In the best studies, where the volunteers either received a placebo or else received echinacea, the majority of studies did not find any benefit for echinacea in preventing colds. When you look only at the less well done studies, those that did not use placebos, scientists more often find just a suggestion that echinacea helps to prevent colds. When only the lower-quality studies show an effect, we worry that biases and bad science are influencing the outcome. The results from the better-quality studies are more trustworthy. These studies tell us that echinacea does not prevent colds. The summary of the high-quality studies also concludes that echinacea does not work to treat colds or cold symptoms. In an example of one of the well-crafted studies that was published in the New England Journal of Medicine, doctors divided 400 volunteers into groups that either took a sugar pill or took echinacea. They found that taking echinacea did not change the severity of a volunteer’s cold, nor did it change how the cold progressed.

Some of the studies examining whether echinacea treats colds have found a small improvement in the duration of cold symptoms when echinacea is used for adults. In these, echinacea led to slightly shorter colds in adults, but the results were mixed. For children, echinacea does not improve cold symptoms and can lead to side effects like a bad rash. Once again, when studies show only very small potential benefits, we have to temper our expectations. It is possible that echinacea has a small effect on the duration of the cold, but the effect is not powerful enough to consistently turn up in studies of the herb.

Compilations of studies that were done after the Cochrane review compilation have not provided any more convincing evidence in favor of echinacea. In 2007, a group of researchers claimed that the evidence from fourteen studies suggested that echinacea did shorten cold symptoms by a day or so. Unfortunately, other researchers claimed that those scientists did not combine the studies appropriately and that the results could not be trusted. Another group compiled studies where researchers put the cold virus right into the noses of study participants and then followed up to see if the herb did anything to stop the people with virus in their nose from getting sick.

This is a great way to design studies of whether something works for colds, but echinacea did not work. We know it can be confusing when the science does not agree on a particular topic. In this case, most of the science says that echinacea does not work. And if echinacea does work for helping cold symptoms, the results are not strong enough to produce consistent results. The bottom line is that echinacea does not prevent colds. While echinacea might make your cold linger for a little less time, that is pretty unlikely too.