Double-blind placebo controlled trial of the anxiolytic effects of a standardized Echinacea extract

Phytother Res. 2020 Mar;34(3):660-668. doi: 10.1002/ptr.6558. Epub 2019 Dec 25.


Earlier studies suggested that specific Echinacea preparations might decrease anxiety. To further study the issue, we performed a double blind, placebo controlled trial with a standardized Echinacea angustifolia root extract. Participants were volunteers scoring above 45 points on the state or on the trait subscale of the State Trait Anxiety Inventory (STAI). They were treated with 40 mg Echinacea or with placebo tablets twice daily for 7 days followed by a 3 week-long washout period. Participants were also administered the Beck Depression Inventory (BDI) and the Perceived Stress Scale (PSS). In the Echinacea group, state anxiety scores decreased by approximately 11 points by the end of the treatment period, whereas the decrease was around 3-points in the placebo group (p< 0.01). The effect maintained over the washout period. The difference from placebo was significant from the 7th day of treatment throughout. Changes were less robust with trait anxiety scores, but the preparation performed better than placebo in patients with high baseline anxiety. Neither BDI nor PSS scores were affected by the treatments. Adverse effects were rare and mild, and all were observed in the placebo group. These findings suggest that particular Echinacea preparations have significant beneficial effects on anxiety in humans.

Keywords: Echinacea; STAI; anxiety; clinical trial.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Anti-Anxiety Agents / pharmacology*
  • Anxiety / drug therapy*
  • Arachidonic Acids / adverse effects
  • Arachidonic Acids / chemistry
  • Arachidonic Acids / pharmacology*
  • Double-Blind Method
  • Echinacea / chemistry*
  • Endocannabinoids / adverse effects
  • Endocannabinoids / chemistry
  • Endocannabinoids / pharmacology*
  • Female
  • Humans
  • Male
  • Placebos
  • Plant Extracts / adverse effects
  • Plant Extracts / chemistry
  • Plant Extracts / pharmacology*
  • Plant Roots / chemistry
  • Polyunsaturated Alkamides / adverse effects
  • Polyunsaturated Alkamides / chemistry
  • Polyunsaturated Alkamides / pharmacology*
  • Psychiatric Status Rating Scales
  • Psychometrics


  • Anti-Anxiety Agents
  • Arachidonic Acids
  • Endocannabinoids
  • Placebos
  • Plant Extracts
  • Polyunsaturated Alkamides
  • anandamide