FEBRUARY 2002 - TOPIC OF THE MONTH
Press release / Topic of the month - January 2002
Allergic reactions to Echinacea "not to be sneezed at"
SYDNEY (Jan 25, 2002). Allergic reactions to Echinacea may be more common than previously thought, a new study suggests.
Echinacea is a commonly used traditional medicine to ward off colds and help fight infections. An estimated 200 million doses are used by Australians each year.
Reporting 4 new cases of allergic reactions to Echinacea, Australian researchers Dr's Raymond Mullins (University of Canberra) and Robert Heddle (Flinders Medical Centre, Adelaide), also examined reports of adverse reactions to alternative/complementary medicines reported to the Australian Adverse Drug Reactions Advisory Committee (ADRAC).
"Of 483 adverse drug reports, over 10 per cent involved Echinacea, and 26 of these reactions appeared allergic". "The reactions were not to be sneezed at" state Mullins and Heddle, "and included acute asthma attacks, top to toe rashes, throat swelling and even life-threatening anaphylaxis".
Many of the reactions could not be predicted. "Four of the subjects had allergic reactions to their first ever dose". "This is unusual, because you normally have to be exposed to something to become allergic to it".
The authors suggest that patients with allergies might develop allergy to Echinacea by first becoming allergic to similar substances within other plants such as grass or tree pollens.
"This would be consistent with the fact that 1 in 5 patients with allergies had a positive allergy test to Echinacea, even though most had not taken it before". "Unfortunately, allergic people appeared to be at highest risk of reactions, yet 1 in 20 surveyed allergic patients were actually using it as well".
"This was not an 'Australian phenomenon' ". Adverse reactions to Echinacea were found by the authors to have been reported in the USA, UK, Canada and New Zealand.
In an accompanying editorial, Dr Leonard Bielory (New Jersey Medical School) points out that complementary/alternative therapies (CAM) need to be subject to the same benefit/risk analysis as synthetic pharmacological agents. "...there is a need to know not only what CAM can do for us, but also what it can do to us".
The researchers conclude that "we need to challenge the common assumption that natural products are always safe. That is simply not true. When substances like Echinacea are used commonly and largely unsupervised, even rare side-effects are almost inevitable. Allergic patients are most at risk and should be warned appropriately".
SOURCE: Mullins RJ, Heddle R. Adverse Reactions Associated with Echinacea: The Australian Experience. Ann Allergy Asthma Immunol 2002; 88: 42-51.
OTHER REFERENCE:
Bielory L. Adverse reactions to complementary and alternative medicine: ragweed's cousin, the coneflower (echinacea), is "a problem more than a sneeze". Ann Allergy Asthma Immunol 2002; 88: 7-9.
Mullins RJ. Echinacea-associated anaphylaxis. Med J Aust 1998; 168: 170-1
CONTACTS
Dr Raymond J. MULLINS
MB BS, PhD, FRACP, FRCPA
Suite 6, John James Medical Centre
175 Strickland Crescent, Deakin, ACT 2600 AUSTRALIA
Tel: 02-6282 2689
Fax: 02-6282 2526
Email:
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Dr Robert Heddle
MB BS, PhD, FRACP, FRCPA
Department of Immunology, Allergy and Arthritis
Flinders Medical Centre
Bedford Park, Adelaide, SA 5042 AUSTRALIA
Tel: 08-8210 9422 or 08-8204 5511
Email:
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STUDY ABSTRACT:
Background:
Fifty per cent of Australians use complementary and alternative medicines (other than vitamins) in any 12 month period, of which Echinacea-containing products are increasingly popular. Recent reports have highlighted the risk of allergic reactions to complementary medicines in atopic patients.
Objective:
To determine the characteristics of adverse reactions linked to use of the popular herbal remedy Echinacea.
Methods:
Five privately-referred patients were evaluated by the authors in their office practice via skin prick testing on the volar aspect of the forearm and RAST following adverse reactions to Echinacea. As there was little published information on adverse reactions to Echinacea, reports to the Australian Adverse Drug Reactions Advisory Committee (ADRAC) were reviewed. Those suggestive of possible allergic reactions were evaluated in greater details by anonymously surveying the health professionals who had reported the cases and from one unreported case. Serum was collected for further analysis where possible.
Results:
Five cases of adverse reactions to Echinacea were personally evaluated by the authors. Two patients suffered anaphylaxis and a third had an acute asthma attack 10 minutes after their first ever dose of Echinacea. The fourth patient suffered recurrent episodes of mild asthma each time Echinacea was ingested and fifth developed a maculopapular rash within 2 days of ingestion which recurred when rechallenged. Three of the patients had positive skin prick tests. Three reported repeated spontaneous "challenges" and symptoms after further ingestion of Echinacea.
Fifty-one Australian adverse drug reports implicating Echinacea were also reviewed. There were 26 cases suggestive of possible IgE-mediated hypersensitivity (4 anaphylaxis, 12 acute asthma, 10 urticaria/angioedema). Of these 26 patients, age ranged from 2-58 years, 78 % were female and over half were known to be atopic. Four were hospitalised, four reacted after their first known exposure, and one patient suffered multiple progressive systemic reactions.
Twenty percent of 100 atopic subjects who had never taken Echinacea also had positive skin prick tests to this substance when tested by (author details suppressed) in his office practice.
Conclusion:
Some atopic subjects have positive skin prick tests to Echinacea in the absence of known exposure. Atopic subjects are also over-represented in those experiencing reactions to Echinacea. The possibility that cross-reactivity between Echinacea and other environmental allergens may trigger allergic reactions in "Echinacea naive" subjects is supported by the Australian data. Given its widespread (and largely unsupervised) community use, even rare adverse events become inevitable. Atopic patients should be cautioned appropriately.
This press release is also available @ www.allergy.org.au
- the website of The Australasian Society of Clinical Immunology and Allergy (ASCIA).
ASCIA is the peak professional body of Clinical Allergists and Immunologists in Australia and New Zealand.
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For further information on allergies, asthma and immune diseases, visit ASCIA Education Resources (AER) @ www.allergy.org.au. A range of AER information bulletins are available, which have been peer reviewed by ASCIA members and represent the available published literature at the time of review .
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