Echinacea: What Makes It Work?

Extrapolations from pharmacological research have led some authors to suggest restrictions or contraindications for the use of Echinacea. This article examines the known chemistry and pharmacology of the various Echinacea species and products, and challenges some of these popular concepts. In particular, the hypotheses that Echinacea is a T cell activator and that it will accelerate pathology in HIV/AIDS, are found to be unsupported by careful analysis of known data. These misunderstandings have arisen mainly from enthusiastic extrapolations of in vitro data on polysaccharide components. The low levels of polysaccharides in most Echinacea products, particularly traditional extracts and tinctures, and their poor bioavailability suggest in most cases the therapeutic activity of Echinacea is due to other component fractions, including the alkylamides. The suggestion that Echinacea should not be prescribed for extended periods of time will be examined in a second article. (Alt Med Rev 1997;2(2):87-93) Echinacea is probably the most widely used herbal medicine in the English-speaking world. Despite its popularity, however, the scientific understanding of how Echinacea works on the immune system is incomplete. The existing scientific information has often been overenthusiastically applied or even misinterpreted. Unfortunately, this has led some writers to suggest restrictions and contraindications for the use of Echinacea which are premature at best, and probably ill-advised. The purpose of this article is to examine the possible pharmacological activities of Echinacea on the immune system, specifically in respect to the suspected active compounds of the herb. Through this process, some of the recently-suggested restrictions of how and when to use Echinacea will be challenged. The first complicating factor is that the term “Echinacea” describes many different preparations currently in use around the world. They include: 1. The stabilized juice of Echinacea purpurea tops, which is often sold under the trade name “Echinacin.” 2. Fresh or dried whole plant or aerial preparations of Echinacea purpurea, E. angustifolia or E. pallida. 3. Fresh or dried preparations from the roots of E. purpurea, E. angustifolia or E. pallida. 4. Mixtures of any of the above. Preparations of either 2, 3, or 4 above are given in various dosage forms including tablets, liquids (in ethanol-water mixtures or other), capsules, and spray-dried powders (in tablets or capsules). Some preparations, especially category 1 above, are often administered by intramuscular injection. It would be unreasonable to expect these diverse preparations and dosage forms to contain the same chemical profile and have the same pharmacological effects in the human body.