Rob McCaleb, president and founder of Herb Research Foundation in Boulder, Colo., calls echinacea "the great herbal convincer."
McCaleb, who has been taking echinacea as needed for the past six years, says people often are surprised to find that the herb works for them.
"Everyone has anecdotes about echinacea," he says.
That's the case with Larry Hickman, staff pharmacist for Home Care Pharmacies in Hagerstown.
Several years ago his daughter, Allison, had a tough time fighting off colds, and she often missed school for five to seven days at a time.
Hickman started giving her a Chinese preparation of echinacea he'd read about, and he says the results were like the difference between night and day.
"She went from missing 30 days a year to missing one or two," he says.
Echinacea is a perennial flower that is easy to cultivate in the garden.
There are several varieties, including purpurea, angustifolia and pallida.
Echinacea purpurea, commonly known as purple coneflower, has produced the most beneficial results in studies.
The plants are harvested for their roots, flowerheads, seeds and juice and can be made into capsules, extracts, tinctures and tea. There are hundreds of echinacea products on the market, including echinacea lozenges.
Interest in echinacea and other natural remedies is growing for a number of reasons, says Dave Russo, pharmacist and owner of The Medicine Shoppe and Natural Health Concepts in Hagerstown.
Natural products don't have the many side effects traditional over-the-counter products do, and they are perceived to be safer, he says.
Hickman says there are no known side effects associated with echinacea. Echinacea is in the same family as ragweed, and some people may be allergic to it.
Natural remedies also are less expensive.
"People are turning to natural medicines because the cost of traditional medicines has gone sky high," Russo says.
What are the risks?
Because echinacea is a dietary supplement and not a drug, it hasn't been evaluated by the U.S. Food and Drug Administration.
There is some controversy over whether echinacea is appropriate for people with autoimmune disorders, McCaleb says.
The herb loses its effectiveness if taken continuously.
Studies have shown that echinacea suppresses the immune system after a period of six to 12 weeks, Hickman says.
He says he takes echinacea capsules at the first sign of a cold or flu, and he combines them with vitamin C. He repeats the dose three or four times a day, and he says the symptoms usually disappear in about a day.
"I think of it as adjunct therapy, something that complements what the body is trying to do in the first place," Hickman says.
Martin Wall, a botanical photographer and herbalist who lives near Greensboro, N.C., says he only uses echinacea when he's feeling run-down.
"I take a lot of it the first day or two. The trick is to take it soon enough, to take enough, and to repeat the dosage," Wall says.