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St. John's Wort

St. John's wort is a yellow-flowered herb whose extracts appear to act on brain chemistry, slowing the reuptake of messengers like serotonin, dopamine and norepinephrine so they stay active longer. Most people look at it for depression, and the evidence is strong: across three pooled analyses covering over 3,000 people, depression symptoms improved. Those results mainly concern mild to moderate depression, and the effect size was moderate rather than dramatic.

Sources: PMID 15684231; PMID 27468236

Best evidence
Grade A
Conditions studied
1
Outcomes
1
Graded outcomes
1000

Evidence by condition

  • Strong
  • Moderate
  • Limited
  • Very limited

1 condition

Depression

Depression: outcomes studied for St. John's Wort
GradeOutcomeEffectSizeStudiesPeopleStudies list
Depression Symptoms

Moderate Improvement

Improves (the measure goes down)Moderate effect3 studies3,064 people

Studies that measured depression symptoms

Key findings

  • Depression SymptomsDepressionImproves (the measure goes down)

Studies cited

3 studies from PubMed

  1. St John's wort for major depression.Cochrane Database Syst Rev · PMID 18843608
  2. St John's wort for depression: meta-analysis of randomised controlled trials.Br J Psychiatry · PMID 15684231
  3. A meta-analysis on the efficacy and safety of St John's wort extract in depression therapy in comparison with selective serotonin reuptake inhibitors in adults.Neuropsychiatr Dis Treat · PMID 27468236

Protocols that include St. John's Wort