Many hail the mystical power of echinacea, an herbal remedy used to treat the common cold. You don't need a prescription for it, and you have options: liquid vs. pill, alone vs. mixed with other herbs, one species of echinacea vs. another. As with many alternative treatments, however, there's a good chance this plant's power lies in the eye of the cold-sufferer.

What the researchers wanted to know: Can drinking echinacea before being inoculated with a cold virus stop a person from getting infected? And then, if the person is infected, can echinacea ward off cold symptoms?

What they did: Researchers assembled a group of 48 healthy adults and randomly divided them into two treatment groups. One group drank a liquid form of Echinacea purpurea, while the other downed a placebo that looked, tasted, and smelled the same as the echinacea. Neither the researchers nor the subjects knew who was receiving which treatment. After seven days of getting treatment, each subject was inoculated with the same cold virus and then isolated in a hotel room to let the virus conduct its business without interference. Subjects continued to get regular treatment throughout their seven days in the hotel. As the subjects coughed and sneezed (or didn't cough and sneeze), researchers kept a record of the symptoms for later analysis.

What they found: Echinacea was weak against the force of the virus: The little bugger infected 92 percent of echinacea recipients (95 percent of placebo recipients were infected). As for symptom control, only 58 percent of echinacea recipients actually got sick (versus 82 percent of placebo recipients), but there were so few people in the study, that could just as well have been because of chance.

What this study means to you: Someday, there will be a cure for the common cold. This probably is not it.

Caveats: The study was done on a small group of people, so the results above aren't statistically significant. Or maybe the results just aren't significant because echinacea doesn't do anything.

Find out more: The American Herbal Products Association—the trade group of companies that manufacture herbal supplements—is pretty sure that herbal supplements are a good idea (http://www.ahpa.org/index.htm). Stephen Barrett, a retired psychiatrist who runs the website Quackwatch, is pretty sure they're not (http://www.quackwatch.org/01QuackeryRelatedTopics/DSH/suppsherbs.html).

Read the article: Sperber, S.J., Shah, L.P., Gilbert, R.D., Ritchey, T.W., and A.S. Monto. "Echinacea purpurea for Prevention of Experimental Rhinovirus Colds." Clinical Infectious Diseases. May 15, 2004, Vol. 38, pp. 1367–71.