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Safety Overview
1.St. John's Wort — At a Glance
St. John's Wort, scientifically known as Hypericum perforatum, is a resilient perennial herbaceous plant belonging to the Hypericaceae family, though historically it was sometimes classified under Clusiaceae. This freely branching shrubby herb typically attains heights ranging from 40 to 80 cm.
Its stems are adorned with numerous oblong, smooth-margined leaves, generally 1 to 3 cm in length. A distinguishing feature of these leaves is the presence of minute translucent spots, visible when held against light, which are actually oil glands. The plant produces abundant five-petaled yellow flowers, each typically 1.0 to 2.0 cm wide, often displaying characteristic black dots along their petal edges.
When crushed, these vibrant flowers release a distinctive blood-red pigment, historically prized for its use in medicinal oils and dyes. By late summer, the flowers mature into small capsules, each containing numerous tiny, dark-brown seeds.
Native to Europe, Hypericum perforatum has successfully naturalized and now flourishes in temperate zones across Asia, Africa, Australia, and both North and South America. It commonly colonizes open, disturbed environments such as meadows, fields, roadsides, and waste grounds, showcasing remarkable adaptability even to poor or degraded soils.
While highly valued for its therapeutic properties, its vigorous growth can lead to its classification as an invasive species in certain regions. It is often listed as a noxious weed due to concerns over its phototoxic effects on grazing livestock, particularly those with light-colored coats, which can develop skin lesions upon exposure to sunlight after ingestion.
Trusted Scientific References
Authoritative external sources for Hypericum perforatum:
St. John's Wort should be interpreted through verified botanical identity, practical care, and responsible safety language. This recovery note adds the missing context needed for a complete profile: match light to the plant's habit, use well-drained soil, water according to season, and avoid unsupported medicinal or edible claims. For publishing, the plant can be presented as a source-backed medicinal plant with clear care guidance, common problem diagnosis, and conservative safety wording.
1.1.St. John's Wort — Distinguishing Points
- ✓Botanical Identity — Hypericum perforatum, characterized by translucent-dotted leaves and red-pigment-producing flowers.
- ✓Primary Medicinal Use — Well-researched for its efficacy in treating mild to moderate depression and anxiety.
- ✓Key Bioactive Compounds — Contains naphthodianthrones (hypericin, pseudohypericin) and phloroglucinol derivatives (hyperforin).
- ✓Broad — Spectrum Action — Exhibits antidepressant, anxiolytic, anti-inflammatory, antiviral, and antibacterial properties.
- ✓Traditional Application — Historically used topically for wound healing and internally for nervous system disorders.
- ✓Significant Drug Interaction Potential — Known to interact with a wide range of pharmaceuticals, requiring medical oversight.
- ✓Phototoxic Potential — May cause increased sensitivity to sunlight in some individuals.
- ✓Global Distribution — Native to Europe but naturalized across temperate regions worldwide.
- ✓Invasive Tendency — Can be considered an invasive weed in certain agricultural and ecological contexts.
- ✓Antioxidant Rich — Abundant in flavonoids and phenolic acids, contributing to its protective health benefits.
1.2.St. John's Wort — Quick Summary
- ✓Hypericum perforatum — A perennial herb known for its bright yellow flowers and medicinal properties.
- ✓Mood Support — Primarily used for mild to moderate depression, anxiety, and Seasonal Affective Disorder.
- ✓Active Compounds — Hypericin, pseudohypericin, and hyperforin are key constituents responsible for its therapeutic effects.
- ✓Significant Drug Interactions — Potent inducer of liver enzymes, impacting numerous prescription medications; consulting a healthcare professional is crucial.
- ✓Phototoxicity Risk — Can increase sensitivity to sunlight, requiring caution during sun exposure.
- ✓Traditional Uses — Valued in European folk medicine for wound healing and nervous system support.
2.St. John's Wort — Scientific Identity
3.St. John's Wort — Categories & Tags
4.St. John's Wort — Physical Description
5.St. John's Wort — Traditional Uses
6.St. John's Wort — Chemical Profile
- ✓Naphthodianthrones — Key compounds include hypericin and pseudohypericin, which are primarily responsible for the plant's antidepressant and antiviral activities. They accumulate in the dark glands of the plant.
- ✓Phloroglucinol Derivatives — Hyperforin is the most prominent compound in this class, known for its significant antidepressant, anxiolytic, and antibacterial effects by inhibiting neurotransmitter reuptake and acting as an ion channel modulator.
- ✓Flavonoids — A diverse group including quercetin, rutin, hyperoside, isoquercitrin, apigenin, luteolin, and kaempferol. These contribute to the plant's antioxidant, anti-inflammatory, and neuroprotective properties, and may synergistically enhance antidepressant effects.
- ✓Xanthones — These compounds, such as mangiferin and hyperxanthone, possess antioxidant and anti-inflammatory activities, further contributing to the overall therapeutic profile of Hypericum perforatum.
- ✓Tannins — Present in the plant, tannins provide astringent properties, which are beneficial for wound healing and reducing inflammation, particularly in topical applications.
- ✓Volatile Oils — Comprising monoterpenes and sesquiterpenes like alpha-pinene, limonene, and caryophyllene. While not primary contributors to mood effects, they may offer mild antiseptic and aromatic properties.
- ✓Phenolic Acids — Including chlorogenic acid and caffeic acid, these compounds exhibit antioxidant and anti-inflammatory activities, supporting the plant's overall protective and healing capabilities.
- ✓Oligomeric Proanthocyanidins (OPCs) — These polyphenolic compounds are known for their strong antioxidant activity and ability to support vascular health, contributing to the plant's overall health benefits.
7.St. John's Wort — Pharmacological Findings
- ✓Mood Enhancement — St. John's Wort is widely recognized for its efficacy in managing symptoms of mild to moderate depression and anxiety, primarily by inhibiting the reuptake of neurotransmitters like serotonin, norepinephrine, and dopamine, thereby improving mood regulation.
- ✓Seasonal Affective Disorder (SAD) Relief — Clinical research indicates that Hypericum perforatum can significantly alleviate symptoms associated with seasonal affective disorder, providing mood stabilization during periods of reduced sunlight.
- ✓Wound Healing Acceleration — Topical application of St. John's Wort oil or extracts promotes the faster healing of minor cuts, abrasions, and superficial burns, attributed to its anti-inflammatory and antiseptic properties, as well as its ability to stimulate tissue regeneration.
- ✓Antiviral Activity — Certain compounds within St. John's Wort, notably hypericin, have demonstrated in vitro antiviral effects against enveloped viruses, including herpes simplex virus (HSV), suggesting potential for topical treatment of cold sores.
- ✓Anti-inflammatory Effects — The flavonoids and phloroglucinol derivatives contribute to the plant's anti-inflammatory properties, making it useful in reducing swelling and pain associated with various conditions.
- ✓Nerve Pain Relief — Traditionally and anecdotally, St. John's Wort has been used to alleviate nerve pain, such as neuralgia and sciatica, possibly due to its modulatory effects on neurotransmitters and its anti-inflammatory actions.
- ✓Menopausal Symptom Management — Some studies suggest that St. John's Wort can help reduce certain menopausal symptoms like hot flashes, mood swings, and sleep disturbances, likely through its impact on neurohormonal balance.
- ✓Sleep Quality Improvement — By addressing underlying mood disturbances and promoting relaxation, Hypericum perforatum may contribute to improved sleep patterns and overall sleep quality for individuals experiencing mild insomnia linked to anxiety or depression.
- ✓Antioxidant Protection — The rich array of flavonoids and phenolic acids in St. John's Wort provides significant antioxidant activity, helping to protect cells from oxidative stress and damage caused by free radicals.
- ✓Antibacterial Properties — Hyperforin, a key constituent, exhibits potent antibacterial activity against various gram-positive bacteria, including antibiotic-resistant strains like MRSA, offering potential in both topical and internal applications.
7.1.St. John's Wort — Therapeutic Indications
8.St. John's Wort — Safety & Side Effects
8.1.St. John's Wort — Warnings
- ✓Phototoxicity — Increased sensitivity to sunlight, leading to sunburn-like reactions, especially in fair-skinned individuals or with high doses.
- ✓Digestive Upset — Possible symptoms include nausea, stomach discomfort, or diarrhea in some individuals.
- ✓Dizziness and Headache — Occasional reports of dizziness, lightheadedness, or headaches.
- ✓Dry Mouth — Some users may experience dryness of the mouth.
- ✓Fatigue and Sedation — While often used for mood, some individuals may experience fatigue or mild sedation.
- ✓Sexual Dysfunction — Rarely, side effects like decreased libido or sexual dysfunction have been reported.
- ✓Restlessness or Anxiety — Paradoxically, some individuals may experience increased restlessness or anxiety, especially at higher doses.
8.2.St. John's Wort — Clinical Safety Notes
- ✓Drug Interactions — Potent inducer of CYP3A4 enzymes and P-glycoprotein, significantly reducing the efficacy of numerous medications including oral contraceptives, anticoagulants, antiretrovirals, and immunosuppressants.
- ✓Serotonin Syndrome Risk — Concurrent use with SSRIs, SNRIs, or other serotonergic drugs can lead to a potentially dangerous condition known as serotonin syndrome.
- ✓Pregnancy and Lactation — Not recommended for use during pregnancy or breastfeeding due to insufficient safety data and potential effects on the fetus or infant.
- ✓Bipolar Disorder — Should not be used by individuals with bipolar disorder as it may induce mania or hypomania.
- ✓Surgery — Discontinue use at least two weeks prior to any scheduled surgery due to potential interactions with anesthetics and risk of increased bleeding.
- ✓Children — Generally not recommended for children and adolescents without strict medical supervision due to limited safety and efficacy data in this population.
- ✓Photosensitivity — Individuals should avoid excessive sun exposure and use sun protection while taking St. John's Wort due to increased risk of phototoxicity.
9.St. John's Wort — Preparation Methods
- ✓Standardized Extracts — Commonly available in capsule or tablet form, typically standardized to hypericin or hyperforin content for consistent dosing in treating depression.
- ✓Herbal Tea Infusion — Dried flowers and leaves can be steeped in hot water to make a tea, traditionally used for mild anxiety or digestive discomfort.
- ✓Tinctures — An alcohol-based extract of the fresh or dried herb, allowing for concentrated dosing and ease of absorption, often used for mood support.
- ✓Topical Oil — Macerated fresh flowers infused in a carrier oil (like olive oil) create a red-pigmented oil, excellent for external application on wounds, burns, and nerve pain.
- ✓Poultice — Fresh crushed leaves and flowers can be applied directly as a poultice to minor skin irritations, cuts, or bruises for soothing and healing.
- ✓Glycerites — A non-alcoholic extract using glycerin as a solvent, suitable for children or those avoiding alcohol, often used for its mood-supportive properties.
- ✓Ointments and Creams — Formulations incorporating St. John's Wort extract are commercially available for topical use, particularly for skin irritations, nerve pain, and wound care.
10.St. John's Wort — How to Grow
- ✓Climate Preference — Thrives in temperate climates, tolerating a wide range of conditions but preferring full sun to partial shade.
- ✓Soil Requirements — Adaptable to various soil types, but performs best in well-drained, moderately fertile, sandy or loamy soils with a pH between 5.5 and 7.0.
- ✓Propagation from Seed — Seeds can be sown directly in late autumn or early spring, or started indoors 6-8 weeks before the last frost; requires light for germination.
- ✓Vegetative Propagation — Easily propagated from root cuttings or stem cuttings taken in spring or early summer, ensuring genetic consistency.
- ✓Watering — Requires moderate watering, especially during dry spells; established plants are relatively drought-tolerant.
- ✓Sunlight Exposure — Optimal growth and production of active compounds occur in full sun (at least 6 hours direct sunlight daily).
- ✓Harvesting — Aerial parts (flowers, leaves, and upper stems) are typically harvested at peak flowering, usually in late summer, for medicinal use.
- ✓Pest and Disease Management — Generally robust, but can be susceptible to rust fungi and leaf spot; good air circulation helps prevent fungal issues.
Reviewed by the Flora Medical Global Botanical Review Panel
Multi-disciplinary editorial group · Botany · Ethnobotany · Herbal-medicine literature
Who reviewed this: This page was checked by the Flora Medical Global Botanical Review Panel — an in-house editorial group of botany graduates, ethnobotany researchers, and horticulture practitioners who collectively maintain our 7,000+ plant encyclopedia. Meet the team.
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1. Taxonomic verification
Scientific names and synonyms cross-checked against Kew POWO, World Flora Online, and The Plant List.
2. Phytochemical & medicinal cross-reference
Active compounds, traditional uses, and reported activities are cross-referenced with PubMed, USDA Dr. Duke's database, and peer-reviewed ethnobotanical literature.
3. Conservation & distribution check
Distribution, ecology, and conservation status confirmed against GBIF occurrence records and the IUCN Red List.
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Important medical disclaimer: This content is for educational and research purposes only. It is not medical advice and is not a substitute for consultation with a licensed healthcare provider. Do not use any herb to self-treat a medical condition without professional guidance.
Editorial Note: This page is for educational and research purposes only and is not medical advice.
Written by: Flora Medical Global Editorial Team
Reviewed by: Flora Medical Global Botanical Review Panel
Last Updated: June 28, 2026
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