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Using Echinacea to Treat Colds

Echinacea Studies

Among other scientifically proven actions, echinacea:

  • Increases the number and activity of immune system cells, including anti-tumor cells
  • Stimulates new tissue growth to aid in wound healing
  • Reduces inflammation in arthritis and inflammatory skin conditions
  • Induces mild antibiotic action against bacteria, viruses, fungi, and other germs
  • Inhibits the enzyme hyaluronidase and helps prevent bacterial access to healthy cells
  • Slows the spread of infection to surrounding tissues and helps to flush toxins from infected areas

In Germany, extensive research over the past few decades has uncovered a host of echinacea's infection-fighting properties, including the ability to power up the immune system, treat colds and flu, and prevent infection.

Researchers discovered this after bathing cells in echinacea extract and then exposing them to two potent viruses: those that cause influenza and herpes. Unlike the untreated cells, only a small proportion of echinacea-treated cells became infected.

A study in Germany in 1978 found that in the presence of echinacea, viruses and bacteria had a greatly diminished capacity for causing infections. That means the herb either prevents the virus from reproducing or actively competes with the virus for receptor sites on cells to which the pathogen is naturally attracted, thus preventing microbial invaders from gaining entrance to the cells.

Several research groups have tried to make sense of the echinacea studies using a process called metanalysis. This is a mathematical method that treats all the data of different studies as if the information were part of one large study.

All the groups note that the results of the research are inconsistent, but they do say that various preparations of echinacea have been shown to reduce the risk of catching a cold, to shorten the time people stay sick once infected, and to produce milder symptoms when people do get sick.

For example, one metanalysis conducted by Swiss researchers found that of the three studies that involved people taking standardized extracts of the flowering tops of Echinacea purpurea, the risk of developing a natural cold was about one-half that of people given a placebo (dummy pill). A group of German researchers concluded that extracts of Echinacea purpurea flowering tops are also generally more useful than placebo to reduce duration and severity of symptoms if started soon after a cold beings.

You may have heard about several large studies published in the past few years that came to negative conclusions about the efficacy of echinacea. However, almost all of these studies had serious flaws, which calls into question their validity.

For example, a large study (437 adults participated) of three tinctures of Echinacea angustifolia root was published in the New England Journal of Medicine in 2005. This study found that none of the extracts studied was effective for preventing or treating experimentally induced colds. However, the doses used (1.5 milliliters, or a quarter-teaspoon, three times per day) were dramatically lower than what almost any clinician would ever recommend using.

A similar problem of underdosing (3.75 to 5 milliliters, or three-quarters to one teaspoon, twice per day) was the flaw in a large study of Echinacea purpurea flower juice that found no effects in treating symptoms of natural colds in 407 children (this study was published in the Journal of the American Medical Association in 2004). Still, in this same group of children, taking these low doses did show a moderate ability to prevent them from catching colds.

To learn about how to use echinacea to treat a cold, continue to the next page.