Kava comes from the root of a shrub (Piper methysticum) that grows in the South Pacific. It is ingested as a tea or in capsule form. Active ingredients are thought to be kavalactones.
Strong scientific evidence supports use of kava as an anxiolytic and sleep aid. Mechanism is unknown. Some people use kava for asthma, menopausal symptoms, and UTIs. Dose is 100 mg of standardized extract tid.
Over 20 people in Europe developed liver toxicity (including liver failure) after taking kava, which prompted the FDA to mandate a warning label on kava products. Safety is under continuing surveillance.
When kava is prepared traditionally (as tea) and used in high doses (> 6 to 12 g/day of dried root) or over long periods (up to 6 wk), there have been reports of scaly skin rash (kava dermopathy), blood changes (eg, macrocytosis, leukopenia), and neurologic changes (eg, torticollis, oculogyric crisis, worsening of Parkinson's disease, movement disorders). Also, kava may prolong the effect of other sedatives (eg, barbiturates) and affect driving or other activities requiring alertness.
Last full review/revision May 2009 by Ara DerMarderosian, PhD
Content last modified February 2012