Upper respiratory tract infections have been shown to be responsible for many days of lost productivity every year. The common cold generally lasts five days, while the more serious influenzas can continue for much longer.
Common herbal remedies widely used in the community for colds and flus include echinacea, garlic, rosehips, astragalus and ginger. Of these medicinal plants, echinacea has gained widespread popularity in recent years, particularly in Europe. There are more than 300 preparations containing echinacea for sale in Germany. In 1993 the three most popular of these accounted for 2.5 million medical prescriptions.1
In 1994, a review of 26 controlled clinical trials on the immunomodulatory activity of products containing extracts of echinacea was carried out.1
Primary authors claimed that 30 of the 34 treatment strategies showed the echinacea-containing products to be superior to controls. The reviewers found that oral doses of echinacea were well tolerated. However the variation between studies in all aspects of research design and in the species and mode of preparation of the herbs used, meant that further comparison and extrapolation of results was very difficult.
In contrast to this, a recent report by Mullins2 in the Medical Journal of Australia raised the possibility of echinacea being the causal agent in the anaphylactic reaction experienced by a 37 year old woman. Mullins cites the woman's immediate pharyngeal irritation with echinacea as a reason for not examining other possibilities as causative agents. However, colleagues at Southern Cross University point out, that 'pharyngeal tingling' is common from liquid preparations of two of the three common species of echinacea widely consumed in the Australian community. It is caused by the isobutylamide constituent echinacein, and is not an indication of individual sensitivity to the remedy.3
Mullins also raised concerns about the possibility of widespread sensitivity to echinacea in the community due to cross-reactivity, however such reactions to this plant have not previously been documented in the literature. Interestingly, sunflower seeds are in the same genus as echinacea and as they would share many antigens it could be presumed they too should be highly allergic. Sunflower seeds however are considered safe and are widely consumed in breads, cakes, biscuits and snack foods. Given the immense quantity of echinacea consumed by the global community each year, and the relative low level of reported adverse reactions, it is not inappropriate to presume that it is well tolerated medication.
The British Herbal Compendium4 recommends a dose of 1g three times daily of dried echinacea root (or equivalent) when it is used as a simple (single herb, not in combination). In practice, especially when echinacea is one of a number of remedies combined, the effective dose will be much lower than this.
Sue Evans is a lecturer in herbal medicine at the School of Natural and Complementary Medicine, Southern Cross University, Lismore, NSW, Australia.
email sevans2@scu.edu.au
References
1. Melchart D Linde K et al Immunomodulation with Echinacea - a systematic review of controlled clinical trials. Phytomedicine 1 1994 245-254
2. Mullins RJ Echinacea-associated anaphylaxis. Medical Journal of Australia 168 170-171
3. Myers SP, Wohlmuth H Echinacea-associated anaphylaxis. Letter. Medical Journal of Australia 168 583
4. Bradley P (ed) British Herbal Compendium Volume 1. British Herbal Medicine Association 1992 UK
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