NEW YORK (Reuters Health) - While the jury is still out on whether the popular supplement echinacea fights the common cold, it does seem the innocent-sounding herb can pack drug-like side effects. A 41-year-old man realized this while using echinacea for his flu-like symptoms, according to Canadian researchers.

The case study, published in the February issue of the Journal of the American Academy of Dermatology, highlights the dangers of self-treating and the common misconception that herbal remedies are harmless.

Tender nodules formed under the skin of the man's legs 4 to 5 days after taking the herb. And although the bumps disappeared after several weeks, the man experienced three more episodes of the condition, called erythema nodosum, before being taken off the herb.

Erythema nodosum is a condition that affects the area beneath the skin and causes tender, bruise-like sores, explained co-author Dr. Richard Crawford, a dermatologist and pathologist at the University of British Columbia in Vancouver.

``It's a condition we call reactive. In other words, it is usually instigated by another illness or by a medication. When that instigating agent is taken away, usually the erythema nodosum goes away as well,'' he told Reuters Health.

``When we had (the man) stop taking his echinacea, the episodes of erythema nodosum stopped completely even when he was followed over a year period,'' Crawford said.

Although the use of alternative medicines such as echinacea and other herbs has grown over the past decade, this case study demonstrates that many herbal remedies still generate side effects, just as traditional medical treatments do.

``(Patients) should consider echinacea to be like a prescription medicine in terms of the possibility of producing side effects,'' Crawford noted. ``So if they have any unexplained reaction in their skin, or elsewhere, they could consider herbal medications...along with over-the-counter medications and prescription medications as possible cause for the reaction.''

There is also the possibility that herbal remedies can interact with prescribed drugs. As a result, Crawford said, he encourages patients to report their herbal or alternative medicines to their doctors.

``I think we're at a level of knowledge now that we know that it is potentially very important that traditional physicians know what herbal or alternate medications their patients are taking, just as it would be important for an (alternative) practitioner to understand the traditional therapies that a patient is undergoing,'' he said.

SOURCE: Journal of the American Academy of Dermatology 2001;44:298-299.