Meta-analysis of the efficacy of the acetonic kava-kava extract WS1490 in patients with non-psychotic anxiety disorders

Phytother Res. 2005 Mar;19(3):183-8. doi: 10.1002/ptr.1609.


Introduction: The herbal medicinal product kava-kava, used for treating anxiety disorders, was assessed positively by the Cochrane Review. However, it was withdrawn from the market in Switzerland and Germany due to cases of liver failure and 'unproven' efficacy.

Methods: A protocol for the meta-analysis based on patient source data was written, a literature search was done, and six placebo-controlled, randomized trials with the kava extract WS1490 were identified. The endpoints were the change in HAMA during treatment (continuous and binary).

Results: WS1490 has an effective success rate of OR=3.3 (95% confidence interval of 2.09-5.22) in patients with non-psychotic anxiety disorders. The continuous outcome supports this result: mean improvement with WS1490 by 5.94 (95% confidence interval -0.86 to 12.8) points on the HAMA scale better than placebo. Kava seems to be more effective in females and in younger patients.

Discussion: This meta-analysis has no publication bias, no remarkable heterogeneity and is based on trials with high methodological standards. It is concluded that WS1490, and possibly other kava extracts, are effective. Therefore they remain alternatives to benzodiazepines, selective serotonin re-uptake inhibitors (SSRIs) and other antidepressants in the treatment of non-psychotic anxiety disorders.

Publication types

  • Meta-Analysis

MeSH terms

  • Anti-Anxiety Agents / therapeutic use*
  • Anxiety Disorders / drug therapy*
  • Humans
  • Kava*
  • Phytotherapy*
  • Plant Extracts / therapeutic use*
  • Randomized Controlled Trials as Topic


  • Anti-Anxiety Agents
  • Plant Extracts
  • WS 1490