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Kava kava

Awa; Ava; Piper methysticum; Yagona

Kava kava (Piper methysticum) has been used as a ceremonial drink in the Pacific Islands for hundreds of years. Some people report its effects are similar to alcohol.

The roots are chewed or ground into a pulp and added to cold water. The resulting thick brew, which has been compared to the social equivalent of wine in France, is offered to guests and dignitaries visiting the Pacific Islands.

In addition to its ceremonial uses, kava is best known for its relaxing qualities. Kava is said to elevate mood, well being, and contentment, and produce a feeling of relaxation. Several studies have found that kava may be useful in the treatment of anxiety, insomnia, and related nervous disorders.

However, there is serious concern that kava may cause liver damage. More than 30 cases of liver damage have been reported in Europe. However, researchers have not been able to confirm that kava is toxic to the liver. It is not clear whether kava itself causes liver damage, or whether taking kava in combination with other drugs or herbs is responsible. It is also not clear whether kava is dangerous at previously recommended doses, or only at higher doses. Some countries have taken kava off the market. It remains available in the United States. But the Food and Drug Administration (FDA) issued a consumer advisory in March 2002 regarding the "rare" but potential risk of liver failure associated with kava-containing products.

It is impossible to say what, if any, dose of kava might be safe. You should not take kava unless you are under a doctor's close supervision.

Kava may cause liver damage. DO NOT take kava unless you are under a doctor's supervision. Evidence suggests kava may be helpful for the following health problems:


A number of clinical studies, though not all, have found kava to be effective in treating symptoms associated with anxiety. In a review of 7 scientific studies, researchers concluded that a standardized kava extract was significantly more effective than placebo in treating anxiety. Another study found that kava substantially improved symptoms after only 1 week of treatment. Other studies show that kava may be as effective as some prescription antianxiety medications. According to one study, kava and diazepam (Valium) cause similar changes in brain wave activity, suggesting they may work in the same ways to calm the mind.

Research on using kava for anxiety has decreased because of reports of liver toxicity.

A 2004 study found that 300 mg of kava may improve mood and cognitive performance. That is significant because some prescription drugs used to treat anxiety, such as benzodiazepines (like Valium and alprazolam or Xanax), tend to decrease cognitive function.


Preliminary evidence suggests that kava may help improve sleep quality and decrease the amount of time needed to fall asleep. Due to concerns about kava's safety, and the fact that other herbs can treat sleeplessness, kava is not the best choice for treating insomnia.


Plant Description

Kava is a tall shrub that grows in the islands of the Pacific Ocean. This shrub produces large, green, heart-shaped leaves that grow thickly on the branches. Long, slender flowers grow where the branches meet the stems. The roots look like bundles of woody, hairy branches. The root is the part of the plant used medicinally.

In Fiji, the plant is called "yaquona." In Hawaii, it is known as " 'awa." In Aboriginal tribes, it is referred to as "grog."

What's It Made Of?

The main active ingredients in kava root are called kavalactones (kavapyrones). These chemicals (including kawain, dihydrokawain, and methysticum) have been extensively studied in laboratory and animal studies. They have been found to reduce convulsions, promote sleep, and relax muscles in animals. They also have pain-relieving properties, which may explain why chewing kava root tends to cause a temporary numbness and tingling sensation on the tongue.

Available Forms

In some parts of the world, whole kava roots are chewed for their medicinal value. Kava is also available in liquid form, as tinctures or standardized extracts, and powdered in capsules or tablets.

How to Take It

Because some people have developed severe liver damage, even liver failure, after taking kava, you should only take it under a doctor's close supervision. If you have liver disease (such as cirrhosis or hepatitis), you should not take kava at all.

Kava comes in dried extracts, tablets, capsules, or liquid drops. You can also make a tea by simmering the roots of the plant in water.


Kava should not be given to children.


Given reports of liver damage, it is now impossible to say what dose of kava may be safe. You should take kava only under a doctor's supervision.

DO NOT take kava for more than 4 weeks.


The use of herbs is a time-honored approach to strengthening the body and treating disease. However, herbs contain components that can trigger side effects and interact with other herbs, supplements, or medications. For these reasons, you should take herbs with care, under the supervision of a health care provider qualified in the field of botanical medicine. This is particularly true for kava, because there is evidence it may cause liver damage.

Reports in the United States and Europe have linked kava with severe liver problems. Kava-containing products have been associated with at least 25 reports of liver-related injuries (including hepatitis, cirrhosis, liver failure, and death).

We don't know much about kava's effect on the liver. It may be that the kava supplements some people took were contaminated with other substances that caused liver damage. Or it is possible that some people already had liver problems before taking kava, or that they took a combination of kava and other prescription medications or herbs that damaged their livers. It is also possible that the doses generally recommended for kava affect people differently. So a dose that would cause liver damage in one person might have no effect on the liver in another person.

Because of the uncertainty around kava, you should take it only with your doctor's supervision. If you have taken kava and are having symptoms of:

  • Liver damage, such as yellow skin (jaundice)
  • Fatigue
  • Abdominal pain
  • Loss of appetite
  • Nausea and vomiting; and
  • Joint pain

Seek immediate medical attention.

DO NOT take kava if you have depression, liver disease, such as hepatitis, or Parkinson's disease. Pregnant or breastfeeding women should not take kava.

DO NOT take kava if you are going to have surgery (and tell your surgeon if you have taken it in the past). Kava can prolong the effect of anesthesia.

DO NOT drink alcohol while taking kava.

Other side effects associated with kava include:

  • Allergic skin reactions (such as contact dermatitis)
  • Dizziness
  • Drowsiness
  • Restlessness
  • Stomach upset
  • Tremors

Long-term use at high doses may cause:

  • Flaky, dry, and yellowish discoloration of the skin
  • Hair loss (alopecia)
  • Partial loss of hearing
  • Loss of appetite

Like alcohol, kava may have intoxicating effects and should not be taken before operating a car or other machinery.

Possible Interactions

DO NOT take kava unless you are under the supervision of a doctor, especially if you are being treated for disease. DO NOT take kava with prescription or over-the-counter medications.

Kava may interact with the following:

Anticonvulsants. Kava may increase the effects of medications, such as phenytoin (Dilantin), that are used to treat seizures.

Alcohol. DO NOT use kava and alcohol together. The risk of impairment and the risk of liver damage are greatly increased.

Anti-anxiety agents. Kava may increase the effects of CNS depressants such as benzodiazepines, used for sleep disturbances or anxiety (particularly alprazolam or Xanax), and barbiturates (such as pentobarbital), which are used for sleep disorders and seizures. Benzodiazepines include:

  • Alprazolam (Xanax)
  • Diazepam (Valium)
  • Lorazepam (Ativan)
  • Triazolam (Halcion)
  • Chlordiazepoxide (Librium)

Diuretics (water pills). These drugs help rid the body of excess fluid. Kava can make the effects of these drugs stronger, raising the risk of dehydration.

Phenothiazine medications. Kava may increase the risk of side effects associated with phenothiazine medications (often used for the treatment of schizophrenia), including chlorpromazine (Thorazine); and promethazine (Phenergan), which is used as an antihistamine.

Levodopa.There has been at least one report that kava may reduce the effectiveness of levodopa, a medication used to treat Parkinson's disease. You should not take kava if you are taking any medications containing levodopa or if you have Parkinson's disease.

Medications metabolized by the liver. Because it works on the liver, kava may affect medications that are metabolized by the liver. Speak to your doctor about any medication you are taking before taking kava.

Supporting Research

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Boerner RJ, Sommer H, Berger W, et al. Kava-Kava extract LI 150 is as effective as Opipramol and Buspirone in Generalised Anxiety Disorder--an 8-week randomized, double-blind multi-centre clinical trial in 129 out-patients. Phytomedicine. 2003;10 Suppl 4:38-49.

Cagnacci A, Arangino S, Renzi A, et al. Kava-Kava administration reduces anxiety in perimenopausal women. Maturitas. 2003;44(2):103-109.

Christl SU, Seifert A, Seeler D. Toxic hepatitis after consumption of traditional kava preparation. J Travel Med. 2009;16(1):55-56.

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De Smet PA. Safety concerns about kava not unique. Lancet. 2002;360(9342):1336.

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Ernst E. The risk-benefit profile of commonly used herbal therapies: Ginkgo, St. John's Wort, Ginseng, Echinacea, Saw Palmetto, and Kava. [Review]. Ann Intern Med. 2002;136(1):42-53.

Escher M, Desmeules J, Giostra E, et al. Hepatitis associated with kava, a herbal remedy for anxiety. BMJ. 2001;322:139.

Fu PP, Xia Q, Guo L, Yu H, Chan PC. Toxicity of kava kava. J Environ Sci Health C Environ Carcinog Ecotoxicol Rev. 2008;26(1):89-112. Review.

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      Review Date: 1/1/2017  

      Reviewed By: Steven D. Ehrlich, NMD, Solutions Acupuncture, a private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network. Also reviewed by the A.D.A.M Editorial team.

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