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Other common name(s): purple coneflower, Kansas snakeroot, black sampson, sampson root

Scientific/medical name(s): Echinacea purpurea, Echinacea angustifolia, Echinacea pallida


Echinacea is a wild herb that grows primarily in the Great Plains and eastern regions of North America. It is also cultivated in Europe. It is a member of the family Asteraceae (also called by its older name Compositae.)Three different species of the plant are used in herbal remedies — Echinacea purpurea, Echinacea angustifolia, and Echinacea pallida. Echinacea purpurea is the species most frequently used for research and treatment. Although you can buy echinacea made from any part of these plants, there are 2 main types on the market. One type of echinacea comes from either the stabilized fresh juice of aboveground parts of E. purpurea. The other is an extract of root material (E.angustifolia and/or E. purpurea).


Although echinacea has been widely promoted to help fight colds and flu, there is little scientific evidence that it is effective in preventing, shortening the duration, or relieving the symptoms of these infections. Available scientific evidence does not support claims that echinacea increases resistance to cancer or relieves the side effects of chemotherapy or radiation therapy. Long-term use of echinacea is linked with some side effects as well as potential interference with anesthesia and certain medicines.

How is it promoted for use?

Echinacea is promoted mainly as a treatment for colds, the flu, and other respiratory infections. In Germany, echinacea is a common over-the-counter medication, and more than 300 echinacea products are reportedly sold. Commission E (Germany's regulatory agency for herbs) approved echinacea for treating respiratory infections, urinary tract infections, and poorly healing wounds.

Supporters claim echinacea boosts the body's immune system by stimulating the activity of immune system cells called macrophages, which attack and consume invading organisms, including cancer cells. Some claim that the herb stimulates the anticancer activity of natural killer cells (a type of white blood cell) and therefore could be used as a supplement to chemotherapy or radiation therapy.

What does it involve?

Echinacea is available in capsule and liquid form, but there is controversy over its usefulness in liquid form. Fresh or dried herb can be used to make tea. Although dosage may vary, most practitioners recommend 900 milligrams per day for no longer than 8 weeks to boost the immune system. An injectable form is available outside the United States. You can also buy Echinacea to be applied to the skin.

As with many herbs sold in the United States, there can be problems with quality. A study published in 2003 found that 1 in 10 bottles labeled as containing Echinacea had no measurable trace of it in the final product. Nearly half didn’t contain the species of echinacea listed on the label, and more than 4 in 10 samples didn’t meet the quality standard on the label. The FDA rules about dietary supplements changed starting in 2007, but to date there is little evidence that this situation has improved.

What is the history behind it?

Echinacea has long been used in herbal remedies by Native Americans. In the 19th century, it became a commonly prescribed tonic and was billed as a natural remedy for infections and inflammation. Its use in the United States surged along with interest in natural medicine. In the United States, products labeled as echinacea can be completely different chemical preparations, because of the variety of possible species and plant parts, extraction methods, and the addition of other plant extracts.

What is the evidence?

Many practitioners and patients, particularly in Europe, but also in the United States, are convinced that echinacea has the ability to enhance the immune system and fight off infections from colds and the flu. Although a few laboratory studies suggest that some chemicals found in echinacea might increase the activity of certain immune system cells, human studies have generally concluded that echinacea does not prevent, shorten, or relieve the symptoms of these infections.

A few human studies suggested that echinacea might be of some benefit, but reviews of these studies have found that most tested too few patients or had flaws in the study design that could make the results unreliable. More recently, larger and more rigorously conducted studies have found no benefit for children or adults.

In a 2005 study sponsored by the National Center for Complementary and Alternative Medicine, approximately 400 volunteers were given a standard amount of cold virus. These volunteers were randomly assigned to receive 1 of 3 possible treatments: echinacea starting 1 week before infection, echinacea starting at the time of infection, or a placebo. The volunteers were isolated in hotel rooms to reduce other sources of infection. The researchers found that echinacea was not effective in preventing colds. It also did not reduce how long they lasted or how bad the volunteers’ symptoms were. The researchers even measured the amount of nasal mucus in each volunteer, the number of immune system cells in their noses, and the levels of an immune system hormone in their noses. None of the measurements were influenced by echinacea.

A 2006 review of 22 studies concluded that echinacea does not appear to be effective in preventing colds.

Another study published in 2010 looked at how well Echinacea root worked in people who already had colds. The researchers randomized people into groups to receive placebo (inactive pills) or echinacea, and found no significant differences in how long the colds lasted. .

In terms of how people with cancer use echinacea, the consensus of available scientific evidence does not support claims that echinacea increases resistance to cancer or reduces the immune suppression resulting from chemotherapy.

Are there any possible problems or complications?

This product is sold as a dietary supplement in the United States. Unlike companies that produce drugs (which must be tested before being sold), the companies that make supplements are not required to prove to the Food and Drug Administration that their supplements are safe or effective, as long as they don't claim the supplements can prevent, treat, or cure any specific disease.
Some such products may not contain the amount of the herb or substance that is on the label, and some may include other substances (contaminants). Actual amounts per dose may vary between brands or even between different batches of the same brand. In 2007, the FDA wrote new rules to improve the quality of manufacturing for dietary supplements and the proper listing of supplement ingredients. But these rules do not address the safety of the ingredients or their effects on health.
Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.

Although echinacea is relatively safe, some natural medicine practitioners caution that it may cause liver damage or suppress the immune system if used for more than 8 weeks. They urge people taking medications known to cause liver toxicity, such as anabolic steroids, amiodarone (a drug for heart rhythm problems), and the chemotherapy drugs methotrexate and ketoconazole, to avoid echinacea use. Echinacea may also interact with other drugs. Some of these combinations may be dangerous. Always tell your doctor and pharmacist about any herbs you are taking.

Most practitioners recommend that people with autoimmune disorders such as multiple sclerosis or HIV, people with leukemia, and women who are pregnant or breast-feeding not take echinacea. Careful observation of volunteers who have participated in clinical studies of echinacea have found that serious side effects are uncommon. The most frequent side effects are headache, dizziness, nausea, constipation, and abdominal pain. Rashes may occur, especially in children.

Serious allergic reactions to echinacea have been reported rarely, including itching, trouble breathing, swelling of the face or throat, rash, and wheezing. They are more likely in people who have other allergies or asthma. People with severe allergies to chamomile, ragweed, mugwort, chrysanthemums, asters, sunflowers, zinnias, dandelions, sagebrush, yarrow, tansy, or other members of the Asteraceae family should use caution taking echinacea.

Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.

To learn more

More information from your American Cancer Society

The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-227-2345).

Dietary Supplements: What Is Safe?

The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management

Complementary and Alternative Methods and Cancer

Placebo Effect

Learning About New Ways to Treat Cancer

Learning About New Ways to Prevent Cancer


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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.

Last Medical Review: 07/25/2011
Last Revised: 07/25/2011