Published: September 2011

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Complementary Corner: Echinacea - not to be sneezed at

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Prescriber Update 32(3): 26
September 2011

Many herbal medicines contain pharmacologically active ingredients that have the potential to cause adverse reactions or interact with conventional medicines. One such herbal substance is echinacea.

Preparations containing the roots and aerial parts of Echinacea species are traditionally used for the prevention and treatment of the common cold.^1-3 Three Echinacea species are used: E. purpurea, E. angustifolia and E. pallida.² As for other herbal medicines, commercial preparations have been found to differ appreciably in their composition, mainly due to the use of variable plant material, extraction methods and the addition of other components.³

Constituents identified in echinacea species thought to have pharmacological activity include saturated pyrrolizidine alkaloids, alkylamides, caffeic acid glycosides and polyacetylenes.²,⁵

Echinacea is a member of the Asteraceae (Compositae, daisy) family, which are known to cause allergic reactions. Individuals with allergic tendencies, particularly those with known allergy to other members of the Asteraceae family (e.g. chamomile) should be advised to avoid echinacea preparations.²

CARM has received four reports of allergic-type reactions in which echinacea has been reported as an ingredient in a suspect medicine. Case reports of allergic reactions to echinacea in the literature describe events such as angioedema, pruritis, rash, urticaria, and erythema. Positive skin-prick test results for echinacea have been reported in patients who have experienced allergic reactions temporally associated with echinacea.⁴

Echinacea is postulated to act by stimulating the immune system. A 2006 Cochrane review found some evidence that preparations based on the aerial parts of E. purpurea might be effective for the early treatment of colds in adults; however the results were not consistent between studies.¹

The review also reported that beneficial effects of other echinacea preparations, and echinacea used for preventive purposes might exist but have not been shown in independently replicated, rigorous randomised controlled trials. Clinical efficacy in children remains unclear.

Healthcare professionals are encouraged to ask patients about their use of complementary and alternative medicines and to report all suspected adverse reactions to CARM.

References

1. Linde K, Barrett B, Bauer R, Melchart D, Woelkart K. Echinacea for preventing and treating the common cold. Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD000530. DOI: 10.1002/14651858.CD000530.pub2.http://onlinelibrary. wiley.com/o/cochrane/clsysrev/articles/CD000530/pdf_fs.html. Available at: http://onlinelibrary.wiley.com/o/cochrane/ clsysrev/articles/CD000530/pdf_fs.html
2. Barnes J, Anderson LA & Phillipson JD. 2007. Herbal Medicines (3rd Ed.) London: Pharmaceutical Press. pp217-36.
3. World Health Organization. WHO Monographs on Selected Plants. Volume 1. Geneva: WHO. pp125-44.
4. Mullins RJ, Heddle R. 2002. Adverse reactions associated with Echinacea: the Australian experience. Ann Allergy Asthma Immunol. 88: 42-51.
5. Newall CA, Anderson LA, Phillipson JD. Herbal medicines. A Guide for Helath-care Professionals. 1996. London: Pharmaceutical Press.