St. John's Wort
St. John's Wort (Hypericum perforatum) is a flowering plant whose aerial parts contain hypericin, hyperforin and flavonoids. It is mostly studied for low mood.
Also listed as St. John's Wort Extract, St. John's Wort Aerial Parts, St. John's Wort Aerial Parts Extract, St. John's Wort Glycerite Liquid Extract
What it is studied for
The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.
What is St. John’s wort?
St. John’s wort, Hypericum perforatum, contains several potentially active compounds, including hypericin, hyperforin and flavonoids. Laboratory and animal work suggests effects on neurotransmitter signaling, including serotonin. The antidepressant mechanism is not fully settled. 1
Key studies
The most recent publications linked to St. John's Wort's ratings.
Why people take it
SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.
Questions people ask
Is it an established treatment for severe depression?
No. The review lacked adequate evidence for that population. 2
Does “fewer side effects” mean harmless?
No. Trials reported fewer adverse events than antidepressants but were not designed to detect rare harms. 2
Can I combine it with my antidepressant?
That requires professional review: serotonin-related interactions can be serious. 3
Are all extracts equivalent?
No. Composition and strength differ, so the preparation used in research matters. 4
Sources
- A systematic review of St. John’s wort for major depressive disorder Systematic Reviews, 2016 · Study record
- Kann Johanniskraut bei Depressionen helfen? IQWiG, 2023