NEW YORK (Reuters Health) - Echinacea, the popular herbal remedy that is purported to strengthen the immune system and fight infection, may cause mild or serious allergic reactions in people who use the herb to treat their allergy symptoms, according to two Australian researchers.

``Many equate 'natural' with safety, but it is naive to assume that natural products are always safe,'' study author Dr. Raymond J. Mullins of the University of Canberra in Australia told Reuters Health. ``If one can be allergic to 'natural products' like foods, why not to other plants like echinacea?''

Approximately half of Australia's population uses some type of complementary or alternative medicine, such as echinacea, during any 12-month period, previous study findings show. In fact, Australians reportedly consume about 200 million doses of echinacea per year, or approximately 10 doses per person annually. But the risks and benefits of the herb are not fully known.

To investigate, Mullins and co-author Dr. Robert Heddle of Flinders Medical Centre in Adelaide evaluated five patients who had adverse reactions to echinacea, and reviewed 51 adverse drug reports that implicated the herb. Their findings are published in the January issue of Annals of Allergy, Asthma, & Immunology

Among the five patients, allergy symptoms ranging from dizziness and burning throat to severe breathing difficulties and diarrhea appeared from as few as 5 minutes to as long as 2 days after their exposure to echinacea, the investigators report. A 19-year-old female had an acute asthma attack within 10 minutes of her first-ever exposure to tea with added echinacea.

Furthermore, in almost all of the cases described in the 51 adverse drug reports, symptoms appeared within 24 hours of exposure to an echinacea-containing product, the researchers report. In over half (62%) of the cases, symptoms appeared within 6 hours.

When the investigators used a skin prick allergy test on 100 individuals with allergies to substances other than echinacea, they found that one in five were also allergic to echinacea, even though only three of them had ever consumed the herb.

``This is unusual, because you normally have to be exposed to something to become allergic to it,'' Mullins and Heddle write in a statement. They explain that in this case, the study participants may have been allergic to pollen or some other substance that contains the same proteins or substances found in echinacea.

``The presence of positive allergy tests to echinacea in 20% allergic subjects who have never taken echinacea raises the possibility that...allergic patients may be at particular risk of developing life-threatening reactions to complementary medicines with even their first exposure,'' Mullins said.

``Even rare adverse reactions become almost inevitable when a medication--conventional or complementary--is popular, and used largely unsupervised by a large number of people,'' he added.

In addition, the study's findings are not ``an Australian phenomenon,'' according to Mullins and Heddle. Similar cases of adverse reactions associated with echinacea use have been reported in the US, UK, Canada and New Zealand.

In an accompanying editorial, Dr. Leonard Bielory of the New Jersey Medical School in Newark, writes that echinacea and other complementary/alternative medicines (CAM) should be studied to determine whether the potential risks associated with their use outweigh their expected benefits.

``No patient deserves to be treated with a remedy that is worse than the disease,'' Bielory writes.

``In conjunction with federal agencies such as the Food and Drug Administration and the National Institutes of Health to protect the common good, there is a need to know not only what CAM can do for us, but also what it can do to us,'' the editorialist concludes.

SOURCE: Annals of Allergy, Asthma, & Immunology 2002;88:7-9, 42-51.

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