(Integrative Medicine) - People who suffer from asthma and allergies may be at an increased risk for developing serious adverse reactions to Echinacea purpurea, an herb commonly used to treat influenza and upper respiratory tract infections, according to a study published in the Annals of Allergy, Asthma, and Immunology.

Researchers in Australia evaluated five individuals who developed serious allergic reactions after taking echinacea and reviewed 51 adverse reaction reports submitted to the Australian Adverse Drug Reaction Committee (ADRAC) between 1979 and 2000 that involved the herb. The researchers also performed skin prick tests on 100 individuals with known allergies to substances other than echinacea (such as pollen) to determine whether they were also allergic to the herb. Skin prick tests involve the injection of a small amount of allergen extract (in this case, echinacea) into the skin. If the skin swells and becomes red, the individual is most likely allergic to the substance.

Among the five individuals evaluated, allergy symptoms ranged from dizziness and itchy eyes to chest constriction and severe difficulty breathing. Four of the five people reacted to their first-ever dose of echinacea.

Among the adverse reports submitted to the ADRAC, symptoms included rash, fatigue, severe joint and muscle pain, headache, increased blood pressure, nosebleeds, dizziness, nausea, irregular heartbeat, and kidney failure. In most cases, symptoms appeared within 24 hours of taking the herb. More than half of the 51 reports were from people with known asthma or allergies.

When the researchers performed skin prick tests on 100 people with asthma and allergies, they found that 20% were also allergic to echinacea. Notably, only three participants had ever ingested the herb.

The researchers explain that people with asthma or allergies may also be allergic to echinacea because the herb can contain proteins or substances also found in pollen or other environmental allergens. They urge such individuals to consult their healthcare provider before taking echinacea and add that "given [the herb's] widespread (and largely unsupervised) community use, even rare adverse events become inevitable."

References

Mullins RJ, Heddle R. Adverse reactions associated with Echinacea: the Australian experience. Ann Allergy Asthma Immunol. 2002;88:42-51.