Immunmodulation with Echinacea-Containing Drugs

Author(s): Linde, K., Worku, F., Bauer, R., Wagner, H.

Abstract: Objective: To evaluate the evidence for the immunomodulative efficacy of drugs containing extracts of Echinacea.Methods for identifying relevant trials: Multiple methods including on-line searches in Medline and Embase, contacts with researchers and manufacturers, checking references in obtained articles.Study selection: All controlled clinical trials on the prophylactic or therapeutic immunomodulatory efficacy of drugs containing Echinacea in humans.Evaluation of studies: Assessment of methodological quality according to predefined criteria, registration of primary authors' conclusions, and estimation of the amount of evidence by the reviewer.Results: A total of 26 controlled clinical trials was identified; 6 of these tested three different mono-extracts, and 20 tested three different preparations also containing other ingredients. 19 trials investigated the efficacy of the prophylactic or curative treatment of infections, 4 trials the reduction of side-effects of antineoplastic therapies and 3 trials the modulation of various laboratory immune parameters. The primary authors claimed for 30 of the 34treatment strategies an efficacy superior to that of the control group. The methodological quality of most studies was low and only 8 trials scored more than half of the maximum possible score points.Conclusions: The existing controlled clinical trials indicate that preparations containing extracts of Echinacea can be efficacious immunomodulators. However, the evidence is still insufficient for clear therapeutic recommendations as which preparation to use in which dose for a specific indication. Further methodologically sound, randomized clinical trials should be conducted.

Keyword(s): Echinacea

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