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Other common
name(s): kava-kava, kavalactones
Scientific/medical
name(s): Piper
methysticum
Description
Kava is a large shrub with broad, heart-shaped leaves, a
member of the same family as black pepper (the Piperaceae family).
It is native to many Pacific islands, including New Guinea, Fiji,
Tahiti, Samoa, Tonga, and Hawaii. The roots of the plant are used in
herbal remedies and for ceremonies or rituals.
Overview
Some studies support the use of kava for reducing anxiety, and
it is widely used to help with sleep. It may have several effects on
the brain, some of which are similar to prescription tranquilizers. The
safe dosage of kava needed to reduce anxiety is uncertain. Reports of
more than 50 cases of severe liver impairment in people taking kava
supplements have led several countries to ban or restrict sales of
kava. Some of the patients had liver transplants and some died. Side
effects appear to increase with larger doses taken over longer periods
of time. Kava appears to increase the effects of some medicines and can
interfere with anesthesia as well.
How is it promoted for use?
Kava supplements are promoted mainly for anxiety, nervous
tension, stress, restlessness, and, at higher doses, sleeplessness.
Many users say the herb improves mood and brings on a sense of
well-being, relaxation, and even euphoria.
In South Pacific folk medicine, a drink made from the kava
root has been used to treat uterine inflammation, headaches, colds,
rheumatism, and menopausal symptoms. In these traditional settings, the
kava root is chewed, ground, or beaten, then soaked in cold water or
coconut milk. Users drink the liquid to relieve headaches, restore
vigor, promote urination, soothe upset stomachs, ease symptoms of
asthma and tuberculosis, and cure fungal infections. Some users believe
that kava inhibits the growth of the gonorrhea bacteria. The leaves and
branches of the kava plant are sometimes applied to the skin. Kava
creams are used to soothe stings and inflamed skin.
Kava is not promoted as an anti-cancer treatment. While its
reputation for easing mild anxiety may be of interest to people with
cancer, there are many effective prescription medicines and many
non-medical treatments (including complementary mind-body methods) for
anxiety that patients can discuss with their doctors.
What does it involve?
Kava is available as a tablet, capsule, cream, and as a
powder, which can be made into tea or mixed with other drinks. Daily
doses range from 50 to 240 milligrams of kavalactones (the active
ingredient in kava). For anxiety, it may be taken several times a day.
For sleep, it is taken about an hour before bedtime.
Kava dietary supplements are made by using solvents to extract
kavalactones from kava roots. There are reports that some manufacturers
have also used the peelings from kava stems, which contain a possible
toxin. Differences in quality and type of ingredients and methods of
extraction mean that the kava used as a dietary supplement is not the
same as the kava used in the traditional Fijian, Samoan, and Tongan
cultures. There is some question about whether the differences between
the plant as used traditionally and kava dietary supplements may
account for the rare but extreme cases of toxicity that have been
linked to supplements.
Because of reports of liver failure caused by kava
supplements, Germany, France, the United Kingdom, the Netherlands,
Canada, and Switzerland have all banned or restricted kava. The U.S.
Food and Drug Administration (FDA) and the Centers for Disease Control
and Prevention have issued warnings about liver failure to U.S.
consumers.
What is the history behind it?
The people of the South Pacific have used kava socially,
ceremonially, and medicinally for thousands of years. A beverage
prepared from the kava root is traditionally offered to visiting
royalty and dignitaries and served at meetings of village elders. The
drink is also often shared at social gatherings.
Accounts of kava first came to the West from the English naval
officer Captain James Cook, who encountered the plant during a trip to
Polynesia in the 1770s. Interest in kava spread quickly. Kava first
underwent medical investigation in the 1860s and by the end of the 19th
century, kava preparations were available in German pharmacies.
What is the evidence?
Kava has been the focus of dozens of medical studies, some of
which support claims made about the herb’s usefulness for
mild anxiety. Kava appears to ease symptoms of tension, nervousness,
and stress. In recent studies, patients with varying levels of anxiety
took kava extract, and many reported relief within days or weeks. It
does not appear to be very effective in those with moderate to severe
anxiety.
Some researchers have found that kava compares well to
prescription anti-anxiety medicines. In clinical studies, it caused few
side effects and did not appear to be addictive. One study showed that
kava did not impair reaction time and even improved concentration. In
comparison, common prescription drugs for anxiety slow reaction time.
In other recent clinical trials, however, kava was no more effective
than placebo in treating anxiety or insomnia.
Exactly how kava works is still uncertain. Some scientists
think that kava works in the brain in a similar way to the group of
prescription tranquilizers called benzodiazepines. In addition, it
appears to block dopamine, which may explain how it can produce a
sensation of pleasure. It may also act in other parts of the brain and
other organs.
More research is needed on long-term use and safe dosing.
Studies are also needed to find out whether the cases of liver failure
were caused by the way the kava was processed or by the kava root
itself, and whether the problem can be addressed so that these serious
effects can be avoided in the future.
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.
In rare cases, kava can lead to liver failure and other
life-threatening problems. Even moderate use can lead to abnormal organ
function, including increased levels of liver enzymes. According to the
FDA, people who have had liver problems and those taking medications
that may affect the liver, such as cholesterol-lowering drugs, should
check with their doctors before taking kava. The FDA further recommends
that kava be stopped if symptoms of liver disease, such as jaundice
(marked by brown urine and yellowing of the eyes or skin) occur. Other
symptoms of liver disease include nausea, vomiting, light-colored
stools, unusual tiredness, weakness, stomach pain, and loss of
appetite. People who drink alcohol regularly have a higher risk of
liver damage.
Kava may affect reflexes and judgment, so it should not be
used by people driving or operating heavy machinery. Other side effects
of kava include severe involuntary movements, headache, upset stomach,
drowsiness, trouble breathing, poor appetite, weight loss, scaly skin,
red eyes, abnormal blood cells, blood in the urine, poor coordination,
and muscle weakness. Kava may worsen symptoms in people who have
Parkinson’s disease, seizures, depression, or bipolar
disorder. Studies have not been done on children or women who are
pregnant or breast-feeding, and no safety data is available. Although
rare, some allergic reactions to kava have been reported.
Kava should not be taken with drugs that cause drowsiness,
such as anti-anxiety medicines, muscle relaxants, sedatives, pain
relievers, or alcohol, due to the risk of extreme drowsiness or even
unconsciousness. People taking antidepressants or drugs that affect
dopamine (such as haloperidol, risperidone, metoclopramide, or l-dopa)
should not use kava. Those taking blood-thinning medications may have
increased risk of bleeding. Because of its potential to interact with
anesthetics, people who are planning to have surgery should stop taking
it for 2 to 3 weeks before surgery. In addition, other potential
interactions between kava and other drugs and herbs should be
considered. Always tell your doctor and pharmacist about any herbs you
are taking.
A safe dosage of kava has not been determined. Kava should not
be taken for more than 4 weeks unless recommended by a doctor. 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
Blumenthal M, ed. The
Complete German Commission E Monographs: Therapeutic Guide to Herbal
Medicines. Austin, TX: American Botanical Council; 1998.
Bressler R. Interactions between kava and prescription
medications. Geriatrics.
2005;60;24-25.
Cerrato PL. Natural tranquilizers? RN. 1998;61:61-62.
Connor KM, Payne V, Davidson JR. Kava in generalized anxiety
disorder: three placebo-controlled trials. Int Clin Psychopharmacol.
2006;21:249-253.
Cupp MJ. Herbal remedies: adverse effects and drug
interactions. Am Fam
Physician. 1999;59:1239-1245.
Ernst E. Herbal remedies for anxiety - a systematic review of
controlled clinical trials. Phytomedicine.
2006;13:205-208. Epub 2005 Aug 15.
Gruenwald J. PDR
for Herbal Medicines. 3rd ed. Montvale, NJ: Thomson PDR;
2004.
Jacobs BP, Bent S, Tice JA, Blackwell T, Cummings SR. An
internet-based randomized, placebo-controlled trial of kava and
valerian for anxiety and insomnia. Medicine (Baltimore).
2005;84:197-207.
Kava: a human health risk assessment. technical report series
no. 30, June 2004. Food Standards Australia New Zealand Web site.
http://www.foodstandards.gov.au/_srcfiles/30_Kava.pdf. Accessed June 6,
2008.
Kava. Memorial Sloan-Kettering Cancer Center Web site.
http://www.mskcc.org/mskcc/html/69272.cfm. Updated September 17, 2007.
Accessed June 6, 2008.
Kava. University of Washington Department of Family Medicine
Web site.
http://www.fammed.washington.edu/predoctoral/CAM/images/kava.pdf.
Accessed June 5, 2008.
Overton A. Kava: Case. Utox Update. Utah Poison Control Center.
2001;3:1-2.
Pittler MH, Ernst E. Kava extract for treating anxiety.
Cochrane Database of Sys Rev. 2003;(1):CD003383.
Wong AH, Smith M, Boon HS. Herbal remedies in psychiatric
practice. Arch Gen
Psychiatry. 1998;55:1033-1044.
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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