Annals of Internal Medicine reports today that the popular supplement Echinacea doesn't have a substantial effect on the length or severity of the common cold. Researchers in Wisconsin assigned 719 people who had early cold symptoms to receive no study drug, a pill that they knew contained Echinacea, or a pill that could be Echinacea or a placebo. Patients were asked to keep a record of their cold symptoms twice a day for about a week. Although cold duration was approximately 7 to 10 hours shorter in people who took Echinacea, the difference wasn't statistically significant, and no significant difference in severity was noted, either.
The study's lead author, Bruce Barrett, MD, PhD, told USA Today that echinacea's supporters would probably consider the findings positive but that those who oppose it for the common cold would consider the study "the nail in the coffin." The director of the study's primary funding source, the National Center for Complementary and Alternative Medicine, told USA Today that the center doesn't plan to support future similar research, since existing data make clear that Echinacea's benefit for the common cold, if any, is "very modest."
For more on herbal supplements in internal medicine practice, see this ACP Internist article from October 2009.