Echinacea Found to Be Ineffective

In the past studies on the effectiveness of echinacea for treating the common cold have yielded mixed results. Part of the reason for this may involve the variety of echinacea preparations used in testing. A new study attempted to compensate for these variations by testing the efficacy of three types of Echinacea. The team, lead by Turner RB et al, found that none of the three echinacea preparations they tested fared better than placebo at preventing or treating a cold. Their results are published in the July 28, 2005 edition of New England Journal of Medicine.

Echinacea, also known as purple coneflower, has long been a popular cold remedy in the United States and is currently the primary remedy for minor respiratory infections in Germany. There are three varieties of echinacea used in cold remedies. The effectiveness of echinacea may be affected by the part of the plant used, the method used to extract the "active" material, where the plant was grown, and the time of the year it was harvested.

In an effort to systematically study echinacea remedies, researchers created three carefully defined preparations of Echinacea angustifolia, which they then tested for their effectiveness in the prevention and treatment of the common cold. Four hundred and thirty seven healthy volunteers were then recruited and assigned to one of three groups: prevention, treatment or control. In the prevention group, participants received 300 mg of one of the three echinacea preparations three times a day from seven days before being exposed them to a form of the common rhinovirus and then until five days after exposure. In the treatment group patients received a placebo for seven days before researchers exposed them to the cold virus, and then received 300 mg of one of the three echinacea preparations three times a day for five days after exposure to the cold virus.

None of the three echinacea preparations taken before exposure to the cold virus significantly reduced the number of colds caught by participants, compared to placebo. In addition, none of the three echinacea preparations taken after exposure to the cold virus significantly reduced cold symptoms compared to placebo. This was determined by either the total symptom score or the proportion of study subjects with clinically defined colds. Echinacea also failed to significantly reduce the severity of any individual cold symptom compared to placebo.

One limitation of this study was that researchers did not look at whether echinacea taken before exposure to the cold virus reduced the severity of cold symptoms in volunteers who did come down with a cold. They also did not vary the dosage of echinacea given to the subjects or the source original plants they used.

Article References

Study Says Echinacea Has No Effect on Colds, site accessed on 10/02/05