Kava: Is It Safe?

The South Pacific herb, Kava Kava, is a best-seller — ranking ninth in
retail U.S. sales in mainstream markets in 2000 — based on its proven
ability to relieve stress, anxiety and tension. Recently kava has come
under the scrutiny of the United States Food and Drug Administration
(FDA), which is acting on reports from Europe that kava may damage the
liver. The agency noted that German and Swiss health authorities have
identified approximately 30 cases of sometimes-serious liver toxicity,
including four cases requiring transplantation, and one death, that are
believed to be associated with kava consumption. Based on these reports,
the U.K. has banned sales of kava products and German authorities have
notified manufacturers of kava products that their licenses to market
the herb could be withdrawn.

The Evidence So Far

Closer examination of the scant details available on the 30 European
cases reveals that the vast majority, 21 cases in all, involved the
concomitant use of hepatotoxic drugs and/or alcohol. This is not
significant evidence of hepatotoxicity

Jerry Cott, PhD., former Chief of the Psychopharmacology Research
Program at the National Institute of Mental Health said, “If the
incidence of liver toxicity for kava is correct, then according to
German researchers it is very similar to that of conventional
pharmaceutical anti-anxiety and antidepressant prescription drugs. These
are generally considered to be acceptable (though small) risks,” he
said, referring to the risk-benefit comparison by which conventional
medicines are evaluated. Cott also pointed out that a small clinical
study from Duke University published in October showed no adverse
effects from kava on the liver.

The fact is, you are far likelier to suffer from liver damage by taking
the prescription anti-anxiety drug, Valium, as you are kava, yet it is
taken by millions daily with little question-and with no major adverse
publicity. The over-the counter pain medication, acetominphen (Tylenol),
also has a high incidence of liver toxicity, especially when combined
with alcohol.

The Research

Kava has a long traditional use in the South Pacific at often
considerably higher doses than those used in Europe i with few reported
liver toxic effects, and its safety/toxicity has been studied
extensively in recent years. In 1990 the German government’s Commission
E, a panel of herbal experts in the fields of medicine and pharmacy,
evaluated the scientific and medical literature and had approved the use
of kava as a nonprescription medicine for “nervous anxiety, stress, and

The longest running study conducted to date, with 101 people for 6
months taking 70mg 3/day had negligible side effects, and in fact, more
of the placebo subjects reported side effects than those taking kava.
The researcher concluded that, “in contrast to both benzodiazapines and
antidepressants, kava possesses an excellent side-effect profile.” ii
The safe and effective benefits of kava to relieve symptoms of anxiety
were also supported in a meta-analysis, a systematic statistical review
of seven human clinical trials published in 2000 in the Journal of
Clinical Psychopharmacology, and again in a similar critical review in
2001. The reviews did not find significant adverse effects related to
liver toxicity.

The Industry Response

There has been a strong response by the herbal industry to ensure kava’s
safety. “We are actively proceeding with a number of initiatives on
this issue, both within and outside the industry, working jointly with
regulators and the scientific community to learn as much as we can about
these adverse events and the safety of kava,” said John Cardellina,
Ph.D., Vice President for Botanical Sciences, Council for Responsible

A coalition of trade associations of the dietary supplement industry are
actively engaged in evaluating the information that has been made
available by the German regulatory authorities. They have retained a
highly regarded professional toxicologist from a leading university to
ascertain the nature of the relationship between kava consumption and
liver problems. The organizations include the American Herbal Products
Association, the Council for Responsible Nutrition, the National
Nutritional Foods Association, and the Utah Natural Products Alliance.

Mark Blumenthal of the American Botanical Council emphasized that the
information now coming together on kava needs to be scientifically
evaluated and addressed. And he noted this is being done by FDA and the
trade associations and that “These considerations and cautions represent
a prudent approach to the information presently available.”

Based on the limited information made available to date, Blumenthal
stated that consumers of kava should consider the following if they are
using kava products:

Kava should not be used by anyone who has any liver problems, or by anyone who is taking any drug product with known adverse effects on the
liver, or anyone who is a regular consumer of alcohol.

Since the reports so far are associated with chronic use, Blumenthal
suggests considering that kava not be taken on a daily basis for more
that four weeks. (Note: We consider that to be overly conservative,
preferring the German Commission E’s recommendation of 3 months.)

In addition, Blumenthal noted that consumers should discontinue use if
symptoms of jaundice (e.g., dark urine, yellowing of the eyes) occur.

Consumers should consult their primary healthcare provider if they have
a history of liver problems or suspect possible liver problems before
using kava or continuing its use.

Another possible recommendation is to set maximum doses allowable for
kava, given that adverse reactions have been reported in Germany where
high doses, above recommended levels, are routinely prescribed.
Australia has such a system – with a maximum 125 mg kavalactones per
tablet or capsule, 3g of dried rhizome per teabag and 250mg kavalactones
maximum daily dose for all forms.

The FDA’s Medwatch Program

The FDA has sent a letter to doctors requesting that any adverse events
associated with the use of kava products be promptly communicated to
FDA’s “Medwatch Program.” The letter also noted that there were several
incidents of “serious injury allegedly associated with the use of
kava-containing supplements.” There are however, some problems inherent
in this reporting system, explained in the box, “Clarifying FDA

Clarifying FDA Allegations

The Medwatch site contains numerous “kava toxicity” reports of cases due
to a product sold at a 1996 New Years Eve rave (dance) event, alleged to
contain kava, but in fact, contained a highly toxic industrial chemical,
called 1,4-butane-diol — and absolutely no kava. The Los Angeles police
department toxicologists within weeks published a report to this effect.
Nonetheless, these spurious claims against kava have remained on the FDA
website ever since.

In general, anyone can report anything to Medwatch: no proof of actual
content is required for a posting, which does not protect the public
from the truly bad products, but may, as in this case, wrongfully malign

In conclusion: More thorough investigation is needed before we can draw
any conclusions about kava’s potential toxicity. The entire issue also
points out the importance, and vulnerability of the liver, the chemical
factory that is the site of metabolism of many of the essential body
compounds, and the detoxification center for ingested chemicals.
Ironically, while the topic here is the potential hepatotoxicity of an
herb, the plant kingdom provides us with such life-saving
liver-protective herbs as milk thistle. In fact, in my own clinical
practice, I will add it to the regimen of those who are or have been on
drugs that affect the liver, for protection and restoration of its vital

The current situation does point out that the liver is affected by many
substances, including prescription and non- prescription drugs, as well
as alcohol, which is a major cause of liver damage.

We must be aware that herbs are potent medicines, to be treated with the
appropriate respect regarding potential interactions and toxicity,
including to the liver. On the other hand, kava’s margin of safety far
surpasses that of it’s pharmaceutical equivalent. Nothing would be
gained by previously satisfied consumers of kava, out of fear of these
potential side effects, switching to a more toxic prescription
medication, such as a benzodiazepine, in the mistaken belief that they
were making a safer choice.

Hyla Cass, MD
Author of Kava: Nature’s Answer to Stress, Anxiety, and Insomnia

i Lichtwer Pharma AG Formulation data sheet, November 1998 Lebot V. et
al.,Kava: The Pacific Drug, Yale University Press, 1992, Page 200

ii Volz et al., 1997, Kava Kava extract WS 1490 versus placebo in
anxiety disorders – a randomized placebo controlled 25 week outpatient
trial’, Pharmacopsychiatry 30(1), p1-5.

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Written by Hyla Cass MD

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