Neither E. purpurea root nor E. augustofolia root were approved by
theGermany's commission E.
"People allergic to ragweed, chrysanthemums, and daisies may also be
allergic to echinacea with fatal results.
Chronic use of echinacea may suppress the immune system or potentially cause
liver damage. So the recommendation is not to use it for more than eight
weeks at a time."
http://ohioline.osu.edu/hyg-fact/5000/5408.html
". Two randomized clinical studies in Germany concluded that Echinacea did
not significantly reduce the number, length, or severity of colds and
respiratory infections compared to placebo (an inactive substance or
treatment).
"
Brinkeborn RM, Shah DV, Degenring FH. Echinaforce and other Echinacea fresh
plant preparations in the treatment of the common cold. A randomized,
placebo controlled, double-blind clinical trial. Phytomedicine. 1999;6:1-6.
Grimm W, Muller, HH. A randomized controlled trial of the effect of fluid
extract of Echinacea purpurea on the incidence and severity of colds and
respiratory infections. Am J Med. 1999;106:138-143.