Kava is the most commonly cited herb related to liver toxicity. Kava, an herbal sedative with antianxiety or calming effects, is prepared by extracting the rhizomes of Piper methysticum, a South Pacific plant. The active ingredients of the plant, known as kavalactones, are found mostly in the rhizomes. Early scientific research indicated that kava was as efficacious as antidepressant drugs and tranquillizers in treating anxiety disorders. In fact, kava extracts were considered safe alternatives to drug therapy for treating anxiety disorders before 1998. However, by 2003, 11 cases of hepatic failure had been reported related to the use of kava, including 7 patients requiring liver transplantation and 4 deaths. In 2003, kava was banned in the European Union and Canada, and the FDA issued another warning. By 2009, more than 100 cases of hepatotoxicity had been linked to kava exposure. Many have followed co-ingestion with alcohol, which appears to potentiate the hepatoxicity.
