St. John's Wort

Best for

Improve everyday quality of life

Faint early signal · 810 mg/day for 12 weeks · 1 study , n=81

6 papers · 4 claims · 16 outcomes scored · 4 positive

Outcomes

What st. john's wort actually does, by outcome

Each row is one outcome with effect size, evidence base, the dose that worked in trials, and time to first effect. Magnitude tiers come from native-unit MCID where available, Cohen's d otherwise.

Outcome Effect size Evidence Dose Weeks Rank

Improve everyday quality of life Faint early signal

Fewer days where health problems dictate what you can and cannot do.

1 RCT n=81 810 mg 12 wk

21632064

small

1 RCT n=81

810 mg

12 wk

—

Ease depression symptoms Likely real but unnoticeable

Lowers the weight of sadness, low energy, and emotional numbness over weeks.

3 meta-analyses n=8.1k 810 mg 12 wk #7/41

21632064·27589952·40014460

trivial

3 meta-analyses n=8.1k Meta-analyzed I²=81%

810 mg

12 wk

#7 /41

Ease winter depression symptoms Likely real but unnoticeable

Compensates for the sunlight deficit when days get short.

3 meta-analyses n=8.1k 810 mg 12 wk #5/39

21632064·27589952·40014460

trivial

3 meta-analyses n=8.1k Meta-analyzed I²=81%

810 mg

12 wk

#5 /39

Ease depression tied to chronic pain Likely real but unnoticeable

When pain loosens its grip, mood follows.

3 meta-analyses n=8.1k 810 mg 12 wk #5/39

21632064·27589952·40014460

trivial

3 meta-analyses n=8.1k Meta-analyzed I²=81%

810 mg

12 wk

#5 /39

Outcome	Effect	Evidence	Dose	Weeks	Rank
Improve everyday quality of life Faint early signal	small	1 RCT n=81	810 mg	12 wk	—
Ease depression symptoms Likely real but unnoticeable	trivial	3 meta-analyses n=8.1k Meta-analyzed	810 mg	12 wk	#7/41
Ease winter depression symptoms Likely real but unnoticeable	trivial	3 meta-analyses n=8.1k Meta-analyzed	810 mg	12 wk	#5/39
Ease depression tied to chronic pain Likely real but unnoticeable	trivial	3 meta-analyses n=8.1k Meta-analyzed	810 mg	12 wk	#5/39

Risk profile

Adverse events and known drug interactions

Safety events

drowsiness mild

gastrointestinal upset, headache, sleep disturbance, dizziness mild

headache mild

allodynia mild

erythrodermia mild

hypophosphatemia mild

paresthesia mild

nausea mild

Drug interactions

Drug:Warfarin major decreases concentration

Warfarin major decreases effect

Cyclosporine major decreases concentration

Ethinyl Estradiol major decreases concentration

Norethindrone major decreases concentration

Indinavir major decreases concentration

Ritonavir major decreases concentration

Nevirapine major decreases concentration

Methadone major decreases concentration

Imatinib major decreases concentration

Sources

Generated August 14, 2026

St. John's Wort

What st. john's wort actually does, by outcome

Adverse events and known drug interactions

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