Can echinacea cure the common cold?
BACKGROUND
It’s the season for sniffles and coughs again. The common cold is not just inconvenient; it is one of the 10 most expensive illnesses due to lost days at work and school, visits to doctors and billions spent of numerous remedies.
Echinacea is one of the best selling of all today’s herbal remedies. But some question whether its reputation is little more than an old wife’s tale. In recent years, several randomised controlled trials have tried to resolve disagreements over Echinacea. Their results have been inconsistent and only fuelled the debate.
A few days before Christmas, a new study was published which promised to provide a clearer answer. Just over 700 participants took part, making it the largest study of Echinacea.
The results found no statistically significant benefits for those taking Echinacea. However, the researchers found “trends” toward slightly shorter and milder colds. Those taking Echinacea had symptoms rated 10 per cent milder and got rid of their colds half a day earlier.
Because of this, the researchers reported that their findings would be viewed as positive by Echinacea supporters but as the “nail in the coffin” by critics.
EVIDENCE FROM THE STUDY
Determining whether any cold remedy works is challenging. Colds naturally come and go with differing severities. People vary in their symptoms and how bothersome they become. And they do go away fairly quickly. Hence the old adage: if you have a cold, do nothing and it will be gone in a week; take your favourite remedy and it will be gone in seven days.
Studying Echinacea is further complicated because three different species are commonly used. Most commercial products contain Echinacea purpureaor Echinacea angustifoliaor both. Some products are manufactured from the leaves and stems, but others use the roots. Each of these differences leads to remedies with different compounds. On top of this, some are liquid preparations and others are tablets. Little wonder the results differ when studies use completely different types of products.
This new trial was very well designed. It involved people who caught colds in the community, unlike earlier trials that experimentally induced colds. The trial also used a high-quality standardised product made from roots of the two commonly used Echinacea species.
The study was conducted in Wisconsin, US, where advertisements asked people to call the researchers when they first felt cold symptoms. Participants were randomly assigned to receive placebo, no treatment or Echinacea. They recorded their symptoms twice daily until the cold was gone.
Statistical analysis is needed because differences between groups can arise by chance, especially with cold symptoms. In this study, small differences were found, called trends, but were not large enough to be statistically significant. But there is still a very small chance the benefits were real. That is what believers in Echinacea hang onto.
PROBLEMATIC ASPECTS
Echinacea has few adverse effects. In this study, the same adverse effects were reported in all groups at the same rates. In other settings, Echinacea has led to stomach and intestinal problems in some people, and can cause allergic reactions.
Anyone allergic to plants in the daisy family should be cautious with Echinacea. The most common allergic reactions are skin rashes, sinus problems and irritated throat and mouth, which can be misinterpreted as cold symptoms. If an allergic reaction is suspected, Echinacea should be stopped.
RECOMMENDATIONS
This well-designed study found that Echinacea did not have the benefits needed for it to be viewed as statistically effective. However, the small degree of benefit might be valued by some people. Mark Blumenthal, executive director of the American Botanical Council, said he would continue to take Echinacea because “I hedge my bets”. The principal researcher said he takes ginger tea when he has a cold. It hasn’t been shown to work either, but he likes it.
The US National Center for Complementary and Alternative Medicine funded this study. After investing millions in different studies, they said the pattern was clear. If there are benefits to Echinacea, they are very modest. So, the search continues for a cure for the common cold.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University.
