This summary provides basic information about the herb echinacea--common names, uses, potential side effects, and resources for more information. There are nine known species of echinacea, all of which are native to the United States and southern Canada. The most commonly used, Echinacea purpurea, is believed to be the most potent.

Common Names--echinacea, purple coneflower, coneflower, American coneflower

Latin Names--Echinacea purpurea, Echinacea angustifolia, Echinacea pallida

Echinacea has traditionally been used to treat or prevent colds, flu, and other infections.

Echinacea is believed to stimulate the immune system to help fight infections.

Less commonly, echinacea has been used for wounds and skin problems, such as acne or boils.

The aboveground parts of the plant and roots of echinacea are used fresh or dried to make teas, squeezed (expressed) juice, extracts, or preparations for external use.

On July 28, 2005, The New England Journal of Medicine published the results of a National Center for Complementary and Alternative Medicine (NCCAM)-funded clinical trial of echinacea for the prevention and treatment of the common cold. The researchers were from the University of Virginia School of Medicine, Charlottesville (principal investigator Ronald B. Turner, M.D.), Karl-Franzens Universitaet, Graz, Austria, and Clemson University, Clemson, South Carolina.

The research team tested three laboratory-made preparations made from the roots of a species of echinacea called Echinacea angustifolia. The extracts were made at three different strengths that are most represented in the worldwide literature on echinacea for the common cold. This design allowed clinical effects from different strengths of echinacea to be observed.

Four hundred and thirty-seven healthy, young-adult volunteers were assigned at random to receive either one of the echinacea preparations or a placebo. There were seven subgroups among the volunteers that received various combinations of echinacea and/or a placebo, in two phases: a "prophylaxis" (i.e., preventative) phase and a treatment phase. The prophylaxis phase lasted 7 days. On the seventh day, the already treated volunteers were exposed to a nasal mist containing common-cold virus. Then, they were isolated for 5 days while the team observed and tested them, using state-of-the art measurements and instruments, as to the appearance and severity of cold symptoms.

The team found that taking echinacea had no clinical or significant effects on whether volunteers became infected with a cold or, in those who developed colds, on how severe their symptoms were or how long those symptoms lasted.

Stephen E. Straus, M.D., Director of NCCAM, offered the following comments:

Echinacea is a popular therapy within the area of complementary and alternative medicine (CAM). In fact, a 2004 national survey on CAM use by Americans found that among those who used natural products, echinacea was the most popular product that they used.

The common cold is a major burden on society, and there is not much that conventional medicine can do to prevent it or ease its symptoms. Thus, there is a lot of appeal in the idea of a readily available remedy that might prevent us from getting a cold or make us feel better if we do get one. However, it's important to ask whether science has proven that echinacea really does work for these purposes.

This well-designed study, led by a team with expertise in the preparation and study of herbal medicines and the treatment and prevention of respiratory virus infections, clearly showed that echinacea did not prevent or treat the common cold. These results confirm and extend those of a previous NCCAM study published in 2003 that found a popular echinacea product was not effective in treating colds in children.

There have been criticisms of many prior studies of herbal supplements, such as products not being consistent, dosages being too low or infrequent, or treatment having been started too late or too soon. However, this study addressed these issues through testing to ensure the echinacea products were chemically consistent throughout the study, using internationally recognized doses, and using the current most-powerful approach for testing treatments for the cold virus.

NCCAM is supporting other studies to find out more about echinacea and about other biologically based CAM therapies. These range from studies in the laboratory, to studies carefully establishing dosages, to studies of these therapies for diseases and conditions, building on promising and compelling earlier evidence.

Side Effects and Cautions

When taken by mouth, echinacea usually does not cause side effects. However, some people experience allergic reactions, including rashes, increased asthma, and anaphylaxis (a life-threatening allergic reaction). In clinical trials, gastrointestinal side effects were most common.

People are more likely to experience allergic reactions to echinacea if they are allergic to related plants in the daisy family, which includes ragweed, chrysanthemums, marigolds, and daisies. Also, people with asthma or atopy (a genetic tendency toward allergic reactions) may be more likely to have an allergic reaction when taking echinacea.

Preparations of echinacea, like any herb, can be variable--what's on the label may not always be what's in the bottle. In addition, herbs are biologically active, so there can be side effects or potential herb-drug interactions. At The Women’s Healthcare Group, we feel that it is imperative that you inform us if you are using herbal products or are thinking about using them. We will provide you with accurate, up-to-date information about the product and how it may interact with other medications you may be using.  

For More Information

Visit the NCCAM Web site and view:

     "What's in the Bottle? An Introduction to Dietary Supplements"

      "Herbal Supplements: Consider Safety, Too"

NCCAM Clearinghouse
Toll-free in the U.S.: 1-888-644-6226
TTY (for deaf and hard-of-hearing callers): 1-866-464-3615
E-mail: info@nccam.nih.gov

CAM on PubMed
Web site: www.nlm.nih.gov/nccam/camonpubmed.html

NIH Office of Dietary Supplements
Web site: ods.od.nih.gov