Kava (Piper methysticum) is a plant native to islands of the South Pacific, where it was traditionally used in a beverage to foster relaxation and improved thinking. It is also known as kava kava.

Some clinical studies have found standard doses of kava to be effective in reducing the symptoms of mild to moderate anxiety. (Determining the amount of the active components, called kavalactones, in some of the products sold can be difficult, however.)

In the brain, kavalactones facilitate GABA transmission and bind to sodium and calcium channels, prolonging inactivation. Slow-wave activity on the EEG is increased. Studies in animals have found only weak antiseizure effects, however, and kava has not been tested against seizures in humans.

A study of mice found that some tolerance developed after long-term use of kava. We don't know whether this happens in humans and whether rebound excitability might occur if kava was stopped suddenly after continual use.

Concerns in Germany and Switzerland about cases of serious liver damage in people who used products containing kava prompted the U.S. Food and Drug Administration to issue an advisory to consumers in March 2002. People with liver disease or those taking medications that may affect the liver were warned to consult a doctor before using kava, and anyone who uses kava was advised to be on the lookout for symptoms of liver problems. Kava products were banned from stores in Canada and the UK.

Kava is not recommended for pregnant women or anyone taking antidepressants or benzodiazepines, including Klonopin, Frisium, Ativan, or Valium.

Read more about kava in the "About Herbs" section of the Memorial Sloan-Kettering Cancer Center website. (If you have not visited the site before, the information on kava will be preceded by a Disclaimer.)

Much of the information in this article is based on Spinella M: Herbal medicines and epilepsy: The potential for benefit and adverse effects. Epilepsy Behav 2001; 2(6):524-532. (PMID 12609386)

Topic Editor: Steven C. Schachter, M.D.
Last Reviewed:12/15/06