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Botanical & herbal supplements

St John's Wort

Hypericum perforatum flowering herb extract

St John's Wort is a Hypericum perforatum extract studied mainly in people with depression. It has no established focus or productivity benefit in healthy adults and can interact seriously with many medicines. Compare the exact extract, amount per serving, disclosed hypericin and hyperforin constituents, and batch-testing documentation; equal herb weights do not establish equivalent preparations.

CalmMood SupportMonoamine RelatedWhole HerbStandardized ExtractEuropean HerbalismClinical Research
Updated October 2026/6 min read/7 citations
Reviewed by the NootropicsIndex editorial team.Method: prioritize cited human research and official safety or regulatory sources; compare retailer-listed prices without endorsing products.Affiliate disclosure
01

What is it?

What St John's Wort is

1

St John's Wort is the flowering herb Hypericum perforatum, sold in whole-herb and extract preparations. Its clinical research is mainly in people with depression; those findings do not establish general focus or productivity enhancement.

Evidence and safety snapshot1
Human evidence is mainly from specific extracts and patient populations. Medication interactions are a separate, potentially serious hazard; an ordinary short-term tolerability rating does not describe use alongside medicines.
02

Names, aliases and forms

Latin NameHypericum perforatum
Common NamesSt. John's wort; Klamath weed
Pharmacopeial NameHyperici herba
03

Potential effects and evidence map

Standardized extracts have patient-specific mood evidence, with results varying by extract, country, study quality and comparator. That research does not establish routine healthy-user benefits. Medication studies and official safety sources document reduced exposure to some medicines and serious reactions with serotonin-affecting drugs.

Effect domainMagnitudeGrade
Mood / wellbeing3
CumulativeConfidence: Medium

St John's Wort has human evidence in specific mood/depression research contexts, but this should not be generalized to routine wellness use or mixed with antidepressants.

3/5
B
Calm / relaxation1
UnknownConfidence: Low

A reliable calm or relaxation benefit in generally healthy adults has not been established.

0/5
E
Focus / attention1
UnknownConfidence: Medium

Current human clinical evidence does not establish a focus or productivity benefit in generally healthy users.

0/5
E
04

Typical dosages and timing

Typical
600-900 mg/day
Not a recommendation
Lower bound
600 mg
Profile value
Upper bound
900 mg
Profile value
Extract-specific daily doses5600-900 mg/day

The EMA monograph lists these daily amounts for some oral dry extracts, with other amounts for different preparations. They are medicinal-product context, not a universal whole-herb dose or a self-directed regimen.

Compare by extract5capsules or powder

Match the botanical name and plant part, extraction solvent and ratio, and disclosed hypericin and hyperforin amounts. Equal capsule or powder mass does not establish equivalent extracts. A certificate of analysis (COA) describes testing for a particular batch.

05

Timing & effect horizon

Effect horizonUnknown
Unknown
Study duration3

The clinical evidence comes from repeated-dose depression studies. A study course does not establish a healthy-user onset, a single-dose effect duration, or a recommended cycle.

Constituent timing differs from effect timing5

EMA reports a hypericin plasma peak at 4-12 hours and an elimination The time for blood levels to fall by half during the final elimination phase.Source of about 19-36 hours. These describe one constituent in studied preparations, not a whole-extract half-life or the onset and duration of a nootropic benefit.

06

Safety, side effects and risk profile

Medication interactions are the central risk1
Dangerous interactions are documented with many medicines, including antidepressants, birth control pills, warfarin, transplant medicines, some HIV and cancer drugs, seizure medicines, and heart medicines. The list is not exhaustive.
Pregnancy, lactation and psychiatric cautions5
EMA does not recommend use during pregnancy or lactation or oral use under age 18 because safety data are insufficient. NCCIH also reports rare worsening of psychotic symptoms in people with bipolar disorder or schizophrenia; these populations are outside the ordinary healthy-adult tolerability assessment.
Interaction risk1
Confidence: High

Documented drug interactions can be serious or life-threatening, including reduced effectiveness of critical medicines and dangerous serotonergic combinations.

5/5
B
Evidence uncertainty3
Confidence: Medium

Human evidence is extract- and context-specific; product labels are not interchangeable with clinical-trial extracts.

Unscored
B
Sedation / impairment5
Confidence: Medium

Fatigue and dizziness are reported; adequate driving-performance studies are lacking.

1/5
C
Headache / dizziness1
Confidence: Medium

Headache and dizziness can occur. GI upset and sunlight-related skin reactions are additional tolerability concerns.

1/5
C
Pregnancy / lactation caution5
Confidence: High

Pregnancy and lactation safety is not established; the EMA monograph does not recommend use in these populations.

Unscored
C
Legal / regulatory risk5
Confidence: Medium

As checked in October 2026, U.S. dietary-supplement and EU herbal-medicinal-product frameworks differ; neither implies a single worldwide authorization.

Unscored
C
General tolerability1

In adults taking no medicines, oral use for up to 12 weeks is generally well tolerated. Reported effects include stomach upset, dizziness, restlessness and sleep disturbance. Sunlight-related skin reactions are a concern, especially with high doses. Longer-term and product-specific safety are less certain.

07

Interactions and cautions

Serotonergic combinations2

Combining the herb with medicines that affect serotonin can produce serious serotonin-related toxicity, including serotonin syndrome. This risk is distinct from evidence for a mood benefit.

Drug metabolism and transport5

The herb can increase the activity of drug-metabolizing enzymes and the P-glycoprotein transporter, lowering exposure to some medicines. Hyperforin content affects interaction potential; a low-hyperforin label does not establish compatibility with all medicines.

08

Legal and regulatory status

U.S. and EU context5

As checked in October 2026, St John's Wort is marketed under the U.S. dietary-supplement framework, which does not provide FDA premarket approval of supplements for safety and effectiveness. The EU EMA/HMPC monograph concerns specified herbal medicinal preparations; national product authorizations and permitted claims vary. Neither framework establishes worldwide legal status.

09

Practical buying and quality notes

  • Compare equivalent extract specifications before price per gram or capsule. Check stated amounts of hypericin and hyperforin and whether a batch-specific COA identifies the botanical and tests contaminants. A cheaper unit price does not establish matching composition or medication compatibility.5
  • For capsules, compare the stated extract mass per capsule and capsule count. For powders, compare verified net mass and serving size. A 300 mg serving from a whole-herb powder is not automatically equivalent to 300 mg of a standardized extract. Shipping and regional availability also affect final cost. Verify the package weight and price on the merchant page, especially when a normalized cost appears implausibly low.
10

FAQ

Does St John's Wort work as a nootropic?

3

Human findings in people with depression do not establish a general nootropic effect in healthy adults. Evidence for focus, memory and acute performance remains insufficient.

What St John's Wort dosage has been studied?

5

The compact dosage field describes selected dry-extract daily amounts in the EMA monograph. Other preparations use different doses. Trial or monograph dosing cannot be transferred to an arbitrary product from its mass alone.

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

2

There is no established healthy-user focus-onset or effect-duration estimate. Depression-study courses and measured blood concentrations of constituents answer different questions; neither defines a nootropic cycle.

What should I check before buying St John's Wort?

1

Check the botanical identity, extract specification and disclosed constituent amounts. Compare verified serving and package sizes and batch testing. Medication interactions remain a separate concern even when a product has a clear label and COA.

11

References

  1. NCCIH. St. John's Wort: Usefulness and Safety.
  2. NCCIH. St. John's Wort and Depression: In Depth.
  3. Linde K, et al. St John's wort for major depression. Cochrane Database Syst Rev. 2008;(4):CD000448.
  4. Henderson L, Yue QY, Bergquist C, Gerden B, Arlett P. St John's wort (Hypericum perforatum): drug interactions and clinical outcomes. Br J Clin Pharmacol. 2002;54(4):349-356.
  5. EMA/HMPC. Hyperici herba - herbal medicinal product: European Union herbal monograph.
  6. Asher GN, Corbett AH, Hawke RL. Common herbal dietary supplement-drug interactions. Am Fam Physician. 2017;96(2):101-107.
  7. U.S. Food and Drug Administration. FDA 101: Dietary Supplements. Accessed 19 October 2026.
Note

This page is informational and summarizes available evidence. It is not medical advice, a recommendation, or a substitute for guidance from a qualified clinician.