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interventions / St. John's Wort / mood

Does St. John's Wort help mood? (Grade B evidence)

St. John's Wort probably helps mood (Grade B, moderate certainty), especially in adults, mild-to-moderate depression. Studied doses: 300 mg ×3/day.

Bottom line. St. John's Wort probably helps mood (Grade B, moderate certainty), especially in adults, mild-to-moderate depression. Studied doses: 300 mg ×3/day. []

Direction
benefit
Magnitude
effective for mild-to-moderate depression in trials
Grade
B
Certainty
moderate
Clinical meaning
small but potentially useful
Who it applies to
adults, mild-to-moderate depression
Dose / form studied
Safety
contraindicated_with_ssri
The one limitation
Sample sizes are small in most included trials; effect sizes may shrink with larger studies.

Reviewed · Evidence last changed · Claim clm_ec_sjw_mood v1

Reviewed by Substrate editorial, Independent research collective

⚠ Safety in context

Grade
B
what does the grade mean?
Certainty
moderate
what does certainty mean?

Grade B / moderate: probably helps, and new studies are unlikely to reverse this — but could shrink the effect size.

Who it works for

Best-studied in adults, mild-to-moderate depression. Effective doses cluster around 300 mg ×3/day.

Why this grade

Reasoning trace

Grade B at moderate certainty. The grade reflects the direction and size of the effect across the 0 publishable sources above; certainty reflects heterogeneity, sample sizes, and design quality. What would move it upward: additional well-powered RCTs in the target population that replicate the effect at similar doses. What would move it down: a large null trial, discovery of publication bias, or a retraction of a keystone study.

Dose & form

Studied intake: 300 mg ×3/day.

How it stacks up for mood

Grade history

No grade changes yet. Initial grade assigned; re-reviewed on every 12 months (Grade A/B). Methodology v1.

Re-review cadence: every 12 months (Grade A/B) · methodology v1.

Frequently asked

How long does St. John's Wort take to work for mood?

Trials of St. John's Wort for mood typically report effects within 2–4 weeks, though individual response varies. Studies rarely find benefit inside 1 week for chronic outcomes.

What dose was used in studies of St. John's Wort for mood?

Studied doses for St. John's Wort in mood trials cluster around 300 mg ×3/day. See the dose block for the specific range and how it varies by form.

Does St. John's Wort work for mood if I'm not deficient?

The effect concentrates in adults, mild-to-moderate depression. If your baseline is normal, expect a smaller effect than the trial averages.

St. John's Wort or the next-best alternative for mood?

See the compare block above for the head-to-head with the most-cited alternative. Grade + certainty differences matter more than any single trial.

Related

What this is — and is not

Evidence description
effective for mild-to-moderate depression in trials
Substrate's interpretation
Grade B at moderate certainty — the direction and size the studies converge on, as our reading of the corpus.
Discuss with a clinician
If you're on medication or have a condition that changes the calculus, bring the interaction & population blocks above to your pharmacist or prescriber before deciding.
Individualized medical advice
Not provided here or on any Substrate surface (API, agent tool, embed) — see YMYL policy.

Cite this page

Reuse under CC-BY 4.0 with attribution to evidencebased.info.

Plain-text citation
Substrate. Does St. John's Wort help mood? (Grade B). https://evidencebased.info/interventions/st-johns-wort/mood. Updated 2026.
BibTeX
@misc{substrate_tionsstjohnswortmood,
  author = {Substrate editorial},
  title  = {Does St. John's Wort help mood?},
  year   = {2026},
  url    = {https://evidencebased.info/interventions/st-johns-wort/mood},
  note   = {Grade B, evidencebased.info}
}

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