Hypericum perforatum
Hypericum perforatum
Other names: St John's wort
Yellow flowers; translucent dots in the leaves.
Golden flowers and opposite leaves.
- Family
- Hypericaceae
- Plant type
- Perennial herb
- Safety level (indicative)
- Caution
What the safety levels mean (expand legend)
- Generally recognised as safe. Often a common herb with reasonable harvest and use; still read the specific warnings on the card.
- Information. Primarily informational — details in the text and warnings below matter most.
- Caution. Needs extra care (dose, duration, sensitive groups, interactions).
- Risky. Significant risks — verify sources, contraindications and professional guidance.
- Not for home experimentation. Not suitable to experiment with at home without knowledge and certainty.
- High risk for internal use. Particular risk with internal use (e.g. alkaloids); avoid prolonged or irresponsible dosing.
- Not specified. Level not filled in yet — rely on individual warnings and links below.
Photograph on Wikimedia Commons (CC BY-SA 4.0).
Plant habit
Safety — read before use
For this herb it is important to check warnings, mix-ups and cautions. Start with the Safety section.
Quick overview
A practical summary; details are in the sections below.
- Safety grade
- Caution·details
- Scientific sources on the card
- Yes — sources are listed with claims·Science section
- When and what to harvest
- Flower — June–August
- Processing methods
Herbal infusion (tea), Herbal oil, Honey macerate, Capsules
All methods and recipes on the card- Topics and symptoms
Mood swings, Sadness and melancholy, Topic…
Topics section · Symptoms overview
Identification and mix-ups
Perennial herb with erect, branched stems bearing two distinct longitudinal ridges (the so-called 'two-lined stem'). Leaves opposite, sessile, ovate-lanceolate, with numerous pale translucent oil glands visible when the leaf is held up to light (hence the epithet 'perforatum') and dark black glands along the leaf margin. Flowers golden-yellow, five-petalled, petals with black dots along the margins.
Possible mix-ups and risks
The most significant risk of confusion is with imperforate St John's wort (Hypericum maculatum), which has a distinctly four-angled (square) stem without longitudinal ridges, and translucent leaf glands are sparse or absent — the leaves appear virtually unspotted. The hybrid H. × desetangsii (H. maculatum × H. perforatum) shows intermediate characters. Reliable identification rests on the combination of two longitudinal stem ridges and numerous pale translucent glands scattered across the full leaf blade.
Similar herbs
- Melissa officinalis
Často spolu v diskuzi o „klidu“ a bylinných čajích — třezalka má zvláštní témata interakcí a slunce.
Topics and symptoms
More topics are in the symptoms and topics overview.
- Mood swingsTraditional· Traditional / cultural framing
- Sadness and melancholyTraditional· Traditional / cultural framing
- TopicScientific· Preliminary or weaker scientific findings
- TopicScientific· Preliminary or weaker scientific findingsTraditional· Traditional / cultural framing
- Trauma - gentle symbolic supportTraditional· Traditional / cultural framing
Drug interactions and photosensitivity
Information on the card — not a substitute for professional medical care or individual assessment.
Drug interactions
Hypericum preparations induce CYP3A4, CYP2B6, CYP2C9, CYP2C19 and P-glycoprotein. Concomitant use is contraindicated with: coumarin-type anticoagulants (e.g. warfarin), ciclosporin, everolimus, sirolimus, tacrolimus (systemic), fosamprenavir, indinavir and other HIV protease inhibitors, nucleoside reverse transcriptase inhibitors (NRTIs), irinotecan, imatinib and other cytostatic agents metabolised by the above CYP isoenzymes. Reduced plasma concentrations of hormonal contraceptives may result in unintended pregnancy. Pharmacodynamic interaction: serotonin syndrome (perspiration, tachycardia, agitation, tremor) has very rarely been reported when combined with SSRIs (e.g. sertraline, paroxetine) or buspirone.
Photosensitivity
During treatment, intense UV exposure (sunlight, sunbeds) should be avoided. The photosensitisation risk is attributed to hypericin content.
Sources
Identification
Confusion risk
Drug interactions
Phototoxicity
Geographic occurrence
Czechia
Common (expected wild occurrence in the region)
Widespread occurrence in the Czech Republic in suitable habitats.
Austria
Common (expected wild occurrence in the region)
Wave 1 (seed): broad range in Central Europe — verify with floras and national checklists.
Germany
Common (expected wild occurrence in the region)
Wave 1 (seed): broad range in Central Europe — verify with floras and national checklists.
Hungary
Common (expected wild occurrence in the region)
Wave 1 (seed): broad range in Central Europe — verify with floras and national checklists.
Poland
Common (expected wild occurrence in the region)
Wave 1 (seed): broad range in Central Europe — verify with floras and national checklists.
Slovakia
Common (expected wild occurrence in the region)
Wave 1 (seed): broad range in Central Europe — verify with floras and national checklists.
France
Common (expected wild occurrence in the region)
France: occurrence for the main European catalogue taxa — refine with national atlases / red lists.
Japan
Occasional (garden, cultivation, or fringe of the range)
Japan top 20: temperate and East Asian context — verify Japanese flora and cultivation.
Canada
Occasional (garden, cultivation, or fringe of the range)
Canada / North America top 20 — verify with floras, naturalised populations, and cultivated spread.
Australia
Occasional (garden, cultivation, or fringe of the range)
Australia top 20: archaeophytes and endemics — verify with national floras and introduced-species references.
Harvest
- FlowerJune–August
léto
Region: CzechiaNotes: Flowering tops — watch for photosensitivity.
Storage
- Drying(Leaf)
Keep dried plant material in a sealed container.
- Light:
- Out of direct UV.
- Moisture:
- Low relative humidity.
Processing methods on this herb card
Infusion or brief extraction in hot water; usually without long boiling.
Full method description (from the catalogue)
In the narrow sense, “tea” often means an infusion: you pour water just off the boil over the dried plant matter and let it steep for a few minutes. Temperature, steep time, and the herb-to-water ratio change both flavour and what dissolves into the liquid.
Compared with a decoction, heat exposure is shorter and gentler; tender leaves and flowers are often better as an infusion than with prolonged simmering. For each herb, always follow the plant card for suitable plant part, preparation, and safety notes — general rules never replace species-level judgement.
Traditional context for this method: yes·Scientific context for this method: no
Macerating herbs in a vegetable oil (cold or with gentle heat).
Full method description (from the catalogue)
Herbal oil is made by steeping dried or fresh material in oil (e.g. olive, sunflower) over time, sometimes with gentle warming. The result is not steam-distilled essential oil — it is a different extract type and usage (often topical or culinary per recipe).
Temperature, light, and material moisture affect shelf life; rancid oil must be discarded.
Traditional context for this method: yes·Scientific context for this method: no
Macerating plant material in honey (a honey conserve).
Full method description (from the catalogue)
Honey as a maceration medium creates a viscous mixture with its own biochemistry: water activity, acidity, and enzymes influence shelf life and flavour. Traditionally it is used with delicate flowers or herbs when you want aroma bound into honey.
Infant botulism guidance for honey and honey safety in general sit outside a single herb page; maceration time, ratios, and storage must follow a vetted recipe and source, not this general overview alone.
Traditional context for this method: yes·Scientific context for this method: no
Filling capsules with dried herb or powder; home and industrial variants.
Full method description (from the catalogue)
Capsules allow precise dosing and mask bitter tastes. Home fillers exist, but hygiene, blend uniformity, and storage are harder than with tea.
Follow supplement legislation where it applies.
Traditional context for this method: no·Scientific context for this method: yes
Traditional / spiritual use
Kept separate from science — entries are cultural or symbolic, not medical advice.
Related guides in the library
St John's wort, midsummer, and a yellow field
General
Traditional useFolk useHerbal loreSt John's wort links in many countries to midsummer feasts and a yellow field in the longest days. Calendar and open-land symbolism sit apart from modern drug interaction and photosensitivity warnings on the card.
- Form:
- čaj, olejové maceráty v lidové praxi
- Claim strength:
- Tradition
- Source note:
- Calendar and Christian-cultural layers in Europe; not a spiritual dosing guide.
Scientific notes
Each claim lists a study type and a source (URL or DOI) where available. Dose notes from the literature are informational only.
How to read evidence strength and study type labels
Labels summarise how the catalogue entry is tagged — they are not a medical verdict on efficacy. For every row, read the summary, limitations and source link.
Evidence strength
- Evidence level not specified
- The author did not grade the record; judge from the summary, limitations and source link.
- Narrative / orientational literature
- Descriptive or expert literature without controlled group comparison — context rather than proof of effect.
- Weak evidence
- Study or conclusion with major methodological limits; treat only as a pointer for further reading.
- Preliminary findings
- First or smaller studies — interesting direction, not the final word on efficacy or safety.
- Moderate strength of evidence
- Moderate strength by study design; sample and context limits still apply.
- Stronger evidence
- Stronger design or consistency of results within the study's stated limits.
- Review article
- A review summarises multiple sources; quality depends on review method and field.
Study type
- Narrative / expert text
- Expert text or overview without a classical study design.
- In vitro study
- Cell culture or test-tube experiment — does not show an effect in the body.
- Animal study
- Animal model — transfer to humans is not automatic.
- Observational study
- Observing groups without random treatment assignment; confounding is possible.
- Clinical trial
- Human clinical trial; sample size and control group matter.
- Randomised controlled trial
- Randomised controlled trials are among the stronger designs when well conducted.
- Review study
- A review aggregates multiple papers — quality depends on selection rules.
- Systematic review
- Systematic review with explicit search and selection methodology.
- Meta-analysis
- Statistical pooling of studies; outcome depends on input data and heterogeneity.
- Regulatory assessment / monograph (EMA, WHO…)
- Regulatory body summary for a herbal product — different context from a single RCT; often about products, not home tea.
- Expert monograph (herbal preparations)
- Structured literature summary for a plant or drug — quality depends on author and edition year.
Hypericum perforatum extracts (standardised) show antidepressant activity in several meta-analyses; photosensitivity and extensive CYP450 interactions are well established.
Review articleSystematic reviewYear: 2008Limitations: Not comparable to casual garden tea; induction of drug metabolism can lower levels of oral contraceptives, immunosuppressants, and others; UV skin reactions documented.
Linde K, Berner MM, Kriston L — Cochrane Database of Systematic Reviews
St John's wort for major depression (Cochrane systematic review)
A clinical interactions review summarizes that St John's wort induces CYP3A4 and P-glycoprotein (hyperforin-dependent) and can lower the levels of several drugs (e.g. immunosuppressants, anticoagulants, oral contraceptives); the degree of induction correlates with the hyperforin content of the preparation.
Moderate strength of evidenceReview studyYear: 2020Limitations: Not all commercial preparations contain the same hyperforin level; open-access full text also at PMC7056460; this summary does not replace individual assessment with a doctor or pharmacist.
Meyer zu Schwabedissen HE — British Journal of Pharmacology
Clinical relevance of St. John's wort drug interactions revisited
DOI: 10.1111/bph.14936
The EMA HMPC monograph for St John's wort aerial parts describes approved preparations and a safety framework including interactions; a hot flower infusion is not the same as a standardized extract.
Review articleRegulatory assessment / monograph (EMA, WHO…)Year: 2022Preparation form in the study: infusion
Active compound / focus: hypericin, hyperforin, flavonoids (per the document)
Limitations: A kitchen flower tea may differ from the 'herba' in the monograph; drug interactions remain relevant.
Dose note (from literature): Do not use concurrently with medication without checking with a doctor.
EMA Committee on Herbal Medicinal Products (HMPC) — European Medicines Agency
EMA: Final assessment report on Hypericum perforatum L., herba (revision 1)
Images
The main photo is in the card header. More images will appear here when available.
Safety
What the warning types mean
The type on each warning helps group themes — it does not replace the separate severity badge.
- Internal use
- Risks from swallowing, extracts, duration of use or concentration for internal use.
- Interactions / medicines
- Possible effect on medicines or concurrent treatment — check sources and a professional.
- Raw plant parts
- Raw, unripe or poorly prepared plant parts can be dangerous.
- Toxins and regulation
- Toxic constituents or regulated compounds (e.g. in distillates).
- Contact with the plant
- Skin or mucosa irritation from contact with fresh plant or sap.
- Allergy
- Allergic reactions, often linked to family sensitisation.
- Harvesting and contamination
- Contamination, species mix-ups or harvesting from unsuitable places.
- Photosensitivity and drug interactionsModerate severityInteractions / medicines
St. John's wort can alter the effect of certain medications and increase skin sensitivity to sunlight.