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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
Description
Echinacea is a wild herb that grows primarily in the Great
Plains and eastern regions of North America. It is also cultivated in
Europe. 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. Liquid extracts are made from the leaves and roots or
from the whole plant.
Overview
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; however,
there is controversy over its usefulness in liquid form. 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 also available outside the United States.
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. The
herb's use in the United States has 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 immune system cells,
human studies have generally concluded that echinacea is not effective
in preventing, shortening the duration of, or relieving the symptoms of
these infections.
A few human studies suggested that there might be some
benefit, but reviews of these studies have found that most tested too
few patients or had flaws in the study design that limited the accuracy
of their results. Several larger, more recent, and more rigorously
conducted studies have found no benefit for children or adults.
In a recent 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 or reducing either their duration
or the severity of symptoms reported by the volunteers. 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. It also noted that some
studies of Echinacea
purpurea suggested it may have some value in treating
colds if given shortly after symptoms develop, but the results were not
fully consistent.
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 provide the FDA with results of detailed testing
showing their product is safe and effective before the drug is approved
for sale), the companies that make supplements do not have to show
evidence of safety or health benefits to the FDA before selling their
products. Supplement products without any reliable scientific evidence
of health benefits may still be sold as long as the companies selling
them do not 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 written on the label, and some may include
other substances (contaminants). Though the FDA has written new rules
to improve the quality of manufacturing processes for dietary
supplements and the accurate listing of supplement ingredients, these
rules do not take full effect until 2010. And, the new rules do not
address the safety of supplement ingredients or their effects on health
when proper manufacturing techniques are used.
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. Relying on this type of treatment alone and avoiding or
delaying conventional medical care for cancer may have serious health
consequences.
Additional Resources
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-ACS-2345).
References
Barrett BP, Brown RL, Locken K, Maberry R, Bobula JA,
D’Alessio D. Treatment of the common cold with unrefined
echinacea. A randomized, double-blind, placebo-controlled trial. Ann Intern Med.
2002;137:939-946.
Blumenthal M, ed. The
Complete German Commission E Monographs: Therapeutic Guide to Herbal
Medicines. Austin, TX: American Botanical Council; 1998.
Brinkeborn RM, Shah DV, Degenring FH. Echinaforce and other
Echinacea fresh plant preparations in the treatment of the common cold.
A randomized, placebo controlled, double-blind clinical trial. Phytomedicine.1999;6:1-6.
Echinacea. Memorial Sloan-Kettering Cancer Center Web site.
http://www.mskcc.org/mskcc/html/69209.cfm. Updated July 11, 2007.
Accessed June 4, 2008.
Grimm W, Müller HH. A randomized controlled trial of
the effect of fluid extract of Echinacea purpurea on the incidence and
severity of colds and respiratory infections. Am J Med.
1999;106:138-143.
Kolata G. Study says Echinacea has no effect on colds. NY Times. July 28,
2005.
Linde K, Barrett B, Wölkart K, Bauer R, Melchart D. Echinacea
for preventing and treating the common cold. Cochrane Database Syst
Rev. 2006;(1):CD000530.
Miller LG. Herbal medicinals: selected clinical considerations
focusing on known or potential drug-herb interactions. Arch Intern Med.
1998;158:2200-2211.
Modarai M, Gertsch J, Suter A, Heinrich M, Kortenkamp A.
Cytochrome P450 inhibitory action of Echinacea preparations differs
widely and co-varies with alkylamide content. J Pharm Pharmacol.
2007;59:567-573.
Natural Standard. Herbal/plant therapies: echinacea (e. angustifolia
dc, e. pallida, e. purpurea). Complementary/Integrative Medicine
Education Resources, The University of Texas M.D. Anderson Cancer
Center Web site.
http://www.mdanderson.org/departments/cimer/display.cfm?id=3323E433-E473-4529-A34548F383CD19F5&method=displayFull.
Accessed June 4, 2008. O’Neil J, Hughes S, Lourie A, Zweifler
J. Effects of Echinacea on the frequency of upper respiratory tract
symptoms: a randomized, double-blind, placebo-controlled trial. Ann Allergy Asthma Immunol.
2008;100:384-388.
Sampson W. Studying herbal remedies. N Engl J Med.
2005;353:337-339.
Taylor JA, Weber W, Standish L, Quinn H, Goesling J, McGann M,
Calabrese C. Efficacy and safety of Echinacea in treating upper
respiratory tract infections in children: a randomized controlled
trial. JAMA.
2003;290:2824-2830.
Turner RB, Bauer R, Woelkart K, Hulsey TC, and Gangemi JD. An
evaluation of Echinacea angustifolia in experimental rhinovirus
infections. N Engl J Med.
2005;353: 341-348.
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: 11/01/2008
Last Revised: 11/01/2008
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