Adverse-effect profile of kava

The use of alternative therapies has increased substantially over the last decade, particularly for more chronic conditions such as anxiety. Among the most widely used treatments are medicinal herbs, or phytomedicines, such as kava (Piper methysticum), which has demonstrated anxiolytic activity in both animal models and clinical samples. Kava has several advantages over conventional pharmacologic treatments for anxiety--in clinical settings it has been associated with better tolerability and lack of physiologic dependence and withdrawal. However, phytomedicines are not rigorously regulated in the United States and systematically collected safety data are very limited. These issues are a leading concern regarding the safety of medicinal herbs such as kava. In this report, the safety profile for kava is provided, including findings from a study of its use in generalized anxiety disorder. Safety parameters assessed include occurrence of adverse events, withdrawal symptoms, effect on heart rate, blood pressure, laboratory assessments, and sexual function. No differences were found between kava and placebo on any of the parameters evaluated. The data support the safety of kava in treating anxiety at 280 mg kava lactones/day for 4 weeks.