(Reuters Health) – Though millions will turn to the herb echinacea for some relief this cold season, a study out Monday suggests they will get little, if any, benefit.

Based on their findings, the researchers say they cannot recommend the popular herbal remedy to cold sufferers. But they are not advising people against using it, either.

Echinacea, which is derived from the coneflower, has long been touted as a way to bolster immunity and prevent or ease the common cold.

Over the years, though, studies have come to conflicting conclusions as to whether the herb really works. And even the positive ones have generally suggested modest benefits at best.

In this latest study, published in the Annals of Internal Medicine, researchers pitted an echinacea supplement against inactive placebo pills for easing cold symptoms among 719 adults and teenagers.

They found that echinacea users recovered slightly more quickly — an average of a half-day sooner — and reported somewhat less severe symptoms.

But even those small differences were not quite statistically significant, which means they could have been due to chance.

“this echinacea formulation, which is a good one, did not show any major effect,” said lead researcher Dr. Bruce Barrett, of the University of Wisconsin-Madison.

On the other hand, he told Reuters Health, the findings do not rule out the possibility of a modest benefit.

Barrett said that while some experts will consider this study the “final nail in the coffin” for echinacea as a cold fighter, the positive findings from some past studies complicate the picture.

“before this trial, the evidence was inconclusive,” Barrett said. “And I don’t think we’re past the inconclusive stage.”

So what does that mean for cold sufferers right now? according to Barrett, it depends.

“If you’re an adult who has tried echinacea in the past and been happy with it, this study does not say you should stop using it,” he said. “on the other hand, it certainly doesn’t tell you should start.”

The problem with the common cold is that it can be caused by any of over 200 different viruses. so it is ubiquitous (Americans alone come down with 1 billion colds each year) and resistant to the treatments we throw at it, with symptoms like congestion, sore throat and cough often lasting up to two weeks.

There are treatments that can make symptoms less severe, like acetaminophen for the headache and decongestants for the stuffy nose. But nothing — from cold medications to vitamin C — seems to speed recovery from the infection.

“there are no treatments out there that have been shown to reduce the duration of colds,” Barrett said.

And though a decongestant or cough suppressant might bring some temporary reprieve, they can also have side effects like dizziness, drowsiness or insomnia. so many people opt for alternative remedies that are commonly seen as safer. one study found that from 2000 to 2006, Americans shelled out between $100 million and $200 million per year on echinacea alone.

For the current study, Barrett’s team recruited 719 12- to 80-year-olds who had developed cold symptoms within the past 36 hours. They randomly assigned the patients to take nothing, use placebo tablets or use echinacea tablets; of the echinacea users, half knew they were taking the herb, while the half did not whether they were taking echinacea or the placebo.

The echinacea groups took a formulation made from the root of the plant, which is rich in constituents that, some studies suggest, would be most likely to battle cold symptoms. The patients took eight echinacea tablets on the first day of the study, then four a day over the next four days.

On average, the study found, people in both echinacea groups suffered cold symptoms for between six and seven days. The placebo and no-pill groups differed from them by only a matter of hours — roughly a half-day.

Similarly, there was no clear difference when the researchers looked at the groups’ self-rated symptom severity, which each patient had recorded twice a day while the cold lasted.

The researchers found no evidence that echinacea users suffered side effects, like headache, stomach upset or diarrhea, at a higher rate than the untreated groups.

That’s in line with the low risk of side effects studies have generally found when echinacea is taken as directed — though there is a small chance of allergic reaction.

As far as effectiveness, however, even the studies with positive results suggest echinacea has only modest benefits against cold symptoms.

“No large, well-done clinical trial has shown a large benefit,” Barrett said. “It doesn’t stop a cold in its tracks, that’s for sure.”

For people looking for non-drug ways to soften the blow of cold season, Barrett suggested tactics like getting plenty of fluids, getting enough rest and, yes, having some old-fashioned chicken soup.

Those things may not chase away a cold, but they can help you feel better while it’s around, he said.

The current study was funded by the U.S. National Institutes of Health and the Robert Wood Johnson Foundation. some of the co-researchers on the work are with Warwick, Australia-based MediHerb, maker of the echinacea product used in the study.

Sources

link.reuters.com/fuz54p Annals of Internal Medicine, December 21, 2010.

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