Assessment of the Efficacy of Withania somnifera Root Extract in Patients with Generalized Anxiety Disorder: A Randomized Double-blind Placebo- Controlled Trial

Curr Rev Clin Exp Pharmacol. 2021;16(2):191-196. doi: 10.2174/1574884715666200413120413.


Background: Anxiety disorders are the most universal psychiatric problems in the general population. Due to their chronic nature, these diseases are managed with a multi-drug regimen lasting for a long period of time. Medication discontinuation leads to 25% and 80% recurrence in the first month and the first year, respectively. Despite several treatment approaches, there is no specific and optimal method for patient management. Therefore, it is necessary to find some new therapeutic approaches with fewer side effects. Withania somnifera is a plant with GABAergic property responsible for its anxiolytic effect. The aim of this study was to investigate the effect of W. somnifera root extract as an alternative therapy to reduce standard Generalized Anxiety Disorder (GAD) symptoms.

Methods: Forty patients who met the inclusion criteria (with a confirmed diagnosis of GAD as stated in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) took part in this randomized double-blind placebo-controlled trial and were randomly selected for participation in the treatment group (W. somnifera extract, 1g/day; n = 22) or the placebo group (n = 18). All patients were under treatment with Selective Serotonin Reuptake Inhibitors (SSRIs) and were prescribed one capsule of the extract or placebo per day for six weeks. The Hamilton anxiety rating scale (HAM-A) was used to assess the severity of GAD symptoms at baseline as well as the second and sixth weeks of the trial.

Results: Comparison of the HAM-A scores during the course of the trial revealed a significant amelioration ofHAM-A score in the treatment group versus placebo (14 and 8 units reduction, respectively (P < 0.05)). Moreover, there was a significant difference in the reduction of GAD score between the second (P =0.04) and sixth week (P =0.02) in the treatment group. The extract was safe and no adverse effect was observed during the trial.

Conclusion: W. somnifera extract offers some potential advantages as a safe and effective adjunctive therapy to SSRIs in GAD. The clinical trial protocol has been registered under the Iranian Registry of Clinical Trials (IRCT20180615040105N1).

Keywords: Herbal medicine; Withania somnifera; generalized anxiety disorder; mental disorder; randomized controlled trial.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Anti-Anxiety Agents* / adverse effects
  • Anxiety Disorders / drug therapy
  • Humans
  • Iran
  • Plant Extracts / adverse effects
  • Withania*


  • Anti-Anxiety Agents
  • Plant Extracts