Echinacea is a perennial herb with slender, rough
leaves arranged opposite each other on a stem that
grows to a height of about 18 in (45 cm) and produces
a single large purplish flower. Both the above ground
parts of the plant and the roots are used in dietary
supplements. Fresh leaves are pressed and the resulting
juice is used in extracts or tinctures, or it is combined
with other ingredients to make a paste that can
be applied to the skin. Dried leaves and roots are
powered and made into tea or capsules. An injectable
form of echinacea is available in Europe, but not in the
United States. The active ingredients of echinacea
have not been adequately identified. As a result, it is
difficult to compare the strength and potency of different
forms of the herb or the same formulation made by
different manufacturers.
Safety and effectiveness of Echinacea
Although echinacea has been used for hundreds of
years, only recently have researchers started to examine
its effectiveness in large, independent, rigorously
controlled studies. Many early studies done in Germany
suggested that the herb was effective in treating
certain conditions. In the United States, the National
Center for Complementary and Alternative Medicine
(NCCAM), a government organization within the
National Institutes of Health, is currently conducting
studies on the safety and effectiveness of echinacea in
treating a variety of conditions.
In the United States, the Food and Drug Administration
(FDA) regulates dietary supplements such as
echinacea using the same laws that regulate food,
rather than the laws that regulate prescription and
over-the-counter medications. Unlike conventional
drugs, dietary supplements are not required to
undergo rigorous testing to show that they are safe
and effective before they are marketed to the public.
One consequence of this is that there are many fewer studies of dietary supplements, and some of those
studies are sponsored by the manufacturers who
have an economic investment in positive outcomes.
Too often, studies of dietary supplements are small,
poorly designed, poorly controlled, or incompletely
reported, making it is difficult to draw hard conclusions
about the effectiveness and safety of the product.
The most common use of echinacea in the United
States and Europe is to prevent or shorten and reduce
the severity of symptoms of the common cold, including
sneezing, runny, nose, cough, and fever. Natural
Standard, an independent organization that evaluates
studies, scientific evidence, and expert opinion on complementary
and alternative treatments and makes
impartial judgments concerning their safety and effectiveness
has found that the evidence of effectiveness of
echinacea in treating cold symptoms is mixed. Some
studies have shown that individuals who take echinacea
during cold season are less likely to catch a cold,
but more have found that echinacea has no effect on
whether an individual catches a cold.
On the other
hand, more than half of a substantial number of welldesigned
European studies found that people who take
echinacea at the first sign of a cold feel better sooner
than those who take a placebo or who take nothing.
These results have been contradicted by several large,
well-designed American studies, including one in 2005
of children ages 2–11 that found on average echinacea
did not reduce the length of time the children showed
cold symptoms. Two studies sponsored by NCCAM
also found echinacea did not shorten the symptoms of
colds or influenza or prevent colds.
For years, echinacea has been taken to improve
general health and to treat a variety of infections
because it is thought to boost the immune system.
Laboratory analyses of the ingredients in echinacea
and some animal studies have suggested that echinacea
does stimulate immune system cells. However, this
result has not been confirmed in humans. Research
continues on this use of echinacea.
Claims have also been made that individuals with
AIDS, cancer, and genital herpes can benefit from
taking echinacea. Although there is some theoretical
basis for these claims, there is no clear evidence that
echinacea has an effect on these conditions in humans.
Despite mixed evidence about the effectiveness of
echinacea, the herb generally appears to be safe when
taken by adults in moderate amounts. There is no
standardization of the amount of active ingredient in
products containing echinacea. Guidelines of normal
doses for a 150 lb (70 kg) adult taken three times a day
are:
-1–2 g dried leaves or root brewed into tea
-2–3 mL tincture
-200 mg powdered extract
Lower doses of echinacea for children, based on
the weight of the child, are generally thought to be
safe, although in the cold study mentioned above,
children showed an increased risk of developing a
rash. One study of pregnant women using echinacea
found that moderate use of the herb during the first
three months of pregnancy did not increase the likelihood
of the baby being born with major birth defects.
The safety of echinacea use in breastfeeding women
has not been adequately studied.
