Warning on echinacea: allergy experts

Allergy specialists are warning that echinacea, a herb commonly taken to prevent colds, can cause life-threatening allergic reactions.

Echinacea, or the purple coneflower, is believed to boost the immune system. It's one of the five most popular herbal remedies in the world.

Only three of the nine species of purple coneflower are used medicinally. Various Native American tribes used the herb throughout the 17th and 18th centuries, to alleviate tooth aches, sore throats, coughs, infections, snake bites and other conditions.

Two specialists in Australia studied the remedy and published the results in the January issue of Annals of Allergy, Asthma, and Immunology.

They studied five people who had been skin tested for a possible reaction to echinacea. Three of the five tested positive. They then gave the participants some echinacea to watch their reactions.

After taking the remedy, two of the five people developed a life-threatening reaction called anaphylaxis the airways swell and the blood pressure drops to deadly levels.

A third person had a sudden asthma attack 10 minutes after their first-ever dose of echinacea.

The fourth person had multiple mild asthma attacks each time echinacea was taken. And the last person had a rash within two days of taking the herb, which came back when the echinacea was taken again.

Sensitized through grass, pollen exposure

The findings raise an alarming point: the only way to develop an allergic reaction to a substance is to have been exposed to it before. In this study, at least one of the people had never taken echinacea before.

The researchers concluded that a person can become sensitized to echinacea by coming in contact with other plants in the environment, such as grass or pollens.

They also say people with other allergies are more likely to have a reaction to echinacea.

The results seem to mirror those of a previous study showing one in five people with allergies had a positive skin allergy test to echinacea, even though most had not taken it before.

The researchers also discovered at least 51 other cases of echinacea allergies in Australia, four of which required hospitalization.

"There is a common assumption that natural products are always safe. That is simply not true. When medicines such as echinacea are used so commonly and usually unsupervised, even rare side effects are almost inevitable," said the researchers in their study.

People should always consult their doctor before taking herbal or natural remedies. There's always a chance it could interfere with the drugs you're already taking or with some other health issue.