The Food and Drug Administration (FDA) has issued a "Dear Colleague" letter notifying healthcare professionals that the agency is investigating whether the use of dietary supplements containing kava (also known as kava kava or Piper methysticum) is associated with liver toxicity.

"To help us determine whether there is a problem in the United States, we are asking that you review your cases of liver toxicity to determine if any may be related to the use of kava-containing dietary supplements," the letter stated.

Dietary supplements containing kava are promoted for a variety of uses, including relaxation (e.g., to relieve stress, anxiety, and tension), insomnia, and premenstrual syndrome. The products are marketed to all segments of the population, including children, women, men, and the elderly.

Products containing herbal extracts of kava have been implicated in about 25 cases of serious liver problems in Germany and Switzerland. Side effects have included hepatitis, cirrhosis, and liver failure. At least one patient required a liver transplant.

Based on their assessment of the adverse events reported to them, the regulatory authority in Switzerland has prohibited the sale of products containing the kava extract under review. The German authorities went further by issuing a proposal to remove all kava extract-containing products from the market.

The FDA is investigating whether the use of kava-containing dietary supplements in the United States poses similar public health concerns. The agency has received several reports of serious injury allegedly associated with kava, with at least one report of hepatic failure requiring a liver transplant in a previously healthy young female.

"Due to the potentially serious nature of these concerns, we urge you to report any cases of hepatic toxicity that you think may be related to the use of kava-containing dietary supplements," the letter stated. "Adverse events associated with the use of dietary supplements should be reported as soon as possible."

SOURCE:
U.S. Food and Drug Administration (http://www.fda.gov)