St John's Wort
Hypericum perforatum(?)
Other names: St John's Wort, St. John's Wort, Common St John's wort group, კრაზანა (k'razana), St. John's wort, зверобой (zveroboy)
Photo credit: Didier Descouens
This plant carries serious safety risks. All information is for educational reference only.
Safety information
Toxicity: Photosensitivity (severe skin reactions after sun exposure with large oral/topical doses); diarrhea, dizziness, insomnia, restlessness, paresthesia. | Generally low acute toxicity in humans. Causes photosensitivity (especially in light-skinned individuals and grazing animals). | Mild directly, but major interaction hazard; can cause photosensitivity. | Photosensitization at high doses (rare at usual therapeutic doses — ~30–50× below phototoxic level). | Photosensitisation possible (St John's wort causes sun sensitivity). | Generally low orally; causes photosensitisation (hypericin-driven, more so in fair skin and at higher doses); rarely GI upset, restlessness. | Photosensitivity — large oral doses or topical use may cause severe skin reactions after sun. Other: diarrhea, dizziness, insomnia, restlessness, skin tingling.
Contraindications: Possibly unsafe in pregnancy (birth-defect concern); breastfeeding (infant colic, drowsiness, lethargy). Caution in those on multiple medications. | None specified by source. Modern: photosensitivity; not for combined use with certain antidepressants. | Do not combine with other antidepressants; seek professional advice if on any prescribed medicine; restricted in some countries. | Caution combining with serotonergic drugs. | Pregnancy/breastfeeding caution. | Pregnancy and breastfeeding (insufficient safety data); bipolar disorder (risk of switch to mania); before surgery; concurrent serotonergic medication; planned phototherapy/strong sun exposure. | Possibly unsafe in pregnancy (may increase birth-defect risk); breastfed infants may have colic/drowsiness/lethargy. Caution with fair skin / sun exposure.
Interactions: MAJOR. Potent inducer of CYP3A4 and P-glycoprotein - weakens many drugs: oral contraceptives (contraceptive failure), cyclosporine/tacrolimus (transplant rejection), warfarin, digoxin, simvastatin, anticonvulsants (phenytoin, carbamazepine), HIV drugs (indinavir, nevirapine), some cancer drugs (irinotecan, imatinib, docetaxel), ivabradine. Serotonin syndrome risk with SSRIs/SNRIs/triptans. | None specified by source. Modern (important): a potent inducer of CYP450/P-glycoprotein - interacts with many drugs, reducing effectiveness of oral contraceptives, warfarin, ciclosporin, some HIV/cancer/transplant drugs, and causing serotonin syndrome with SSRIs/triptans. | Significant — induces liver enzymes (CYP450), reducing effectiveness of many drugs (contraceptives, anticoagulants, immunosuppressants, some HIV/cardiac drugs); can be dangerous. | Major. Elevated serotonin with SSRIs (e.g., sertraline). Induces CYP3A4, reducing activity of nonsedating antihistamines, oral contraceptives, certain antiretrovirals, antiepileptics, calcium-channel blockers, cyclosporine, some chemotherapy drugs, macrolide antibiotics, selected antifungals. | If Hypericum perforatum, a strong CYP450/P-gp inducer with major clinically significant interactions - reduces efficacy of antidepressants (serotonin-syndrome risk with SSRIs), oral contraceptives, anticoagulants, ciclosporin, antiretrovirals, digoxin and many others. (Safety gate.) | CLINICALLY IMPORTANT: potent inducer of CYP3A4 and P-glycoprotein (and CYP2C9/1A2) — reduces blood levels of many drugs: combined oral contraceptives (breakthrough bleeding/contraceptive failure), warfarin, ciclosporin/tacrolimus (transplant rejection), antiretrovirals (e.g. indinavir), digoxin, theophylline, some chemotherapeutics (irinotecan, imatinib), anticonvulsants. Pharmacodynamic serotonin-syndrome risk with SSRIs/SNRIs/triptans/MAOIs/tramadol. One of the most clinically significant herb-drug interaction profiles known. | MAJOR — potent CYP450/P-glycoprotein inducer. Weakens antidepressants, birth-control pills, cyclosporine, anticonvulsants (phenytoin, carbamazepine), digoxin, ivabradine, HIV drugs, cancer drugs (irinotecan, imatinib, docetaxel), warfarin, simvastatin. With serotonergic drugs → serotonin syndrome risk.
Pregnancy & breastfeeding: Possibly unsafe in pregnancy (birth-defect concern); breastfeeding caution (infant colic, drowsiness, lethargy). | Caution. | Contraindicated (insufficient safety data). | Possibly unsafe — may increase birth-defect risk; breastfed infants may have colic/drowsiness/lethargy.
Evidence level
Supported by clinical trials in humans.
Preparations
This plant carries serious safety risks. All information is for educational reference only.
infusion · aerial parts
Part used: aerial parts
Traditional use: Traditionally used internally as a nervine for neuralgia, anxiety and tension and (in trials) for mild depression; externally the infused oil for wounds, bruises, mild burns and sunburn.
How to prepare (traditional): Infusion: pour 1 cup of boiling water over 1-2 teaspoons of dried herb and infuse 10-15 minutes. An infused oil of the flowering tops is made for external application (e.g. for sunburn, wounds, bruises).
Dosage note (descriptive only): Drunk three times a day. Standardised extract used in studies: 300 mg three times a day (3-5% hyperforin).
Reference only — not a dosage instruction
tincture · aerial parts
Part used: aerial parts
Traditional use: Nervine / vulnerary.
How to prepare (traditional): Tincture at 1:5 in 40% alcohol.
Dosage note (descriptive only): 2-4 ml three times a day.
Reference only — not a dosage instruction
oil · flower
Part used: flower
Traditional use: Traditionally dabbed onto minor wounds and burns.
How to prepare (traditional): Infused oil made by steeping the flowering tops in oil for about 6 weeks; the red oil is dabbed onto the skin.
Dosage note (descriptive only): professional use only — not provided
Reference only — not a dosage instruction
other · flower
Part used: flower
Traditional use: Traditionally rubbed onto cramps or neuralgia.
How to prepare (traditional): Cream, rubbed onto the affected part.
Dosage note (descriptive only): professional use only — not provided
Reference only — not a dosage instruction
tincture · flower
Part used: flower
Traditional use: Traditionally taken for depression.
How to prepare (traditional): Tincture taken with water.
Dosage note (descriptive only): professional use only — not provided
Reference only — not a dosage instruction
infusion · flower
Part used: flower
Traditional use: Traditionally taken as a digestive tonic.
How to prepare (traditional): Infusion of the flowering tops.
Dosage note (descriptive only): professional use only — not provided
Reference only — not a dosage instruction
Associated conditions
Nutritional notes
Not relevant. | Not relevant; contains hypericin. | Not a food. | Not a nutritional plant. | Not a nutritional food; actives include hypericin and hyperforin.
Healing traditions
Sources (11)
- Keti 2018, "მედეადან დღემდე" (folk)
- Bussmann et al., A comparative ethnobotany ... Republic of Georgia, J Ethnobiol Ethnomed 2016;12:43
- NCCIH St. John's Wort fact sheet (Nicolussi 2020 BJP, PMID 31742659; Apaydin 2016, PMID 27589952; Ng 2017, PMID 28064110; Zhao 2023, PMID 36226689)
- NIH LactMed record for St. John's Wort
- Grieve M., A Modern Herbal — botanical.com/botanical/mgmh/s/sajohn06.html
- Encyclopedia of Herbal Medicine (book, p.106) — Andrew Chevallier, English, 2016
- Hoffmann D., Medical Herbalism (2003) — materia medica, Hypericum perforatum
- Established clinical pharmacology consensus (CYP3A4/P-gp induction; St John's wort-oral contraceptive and -ciclosporin interactions)
- St. John's Wort: Usefulness and Safety — NCCIH/NIH, 2025
- Apaydin et al., Syst Rev 2016;5:148 (PMID 27589952)
- Nicolussi et al., Br J Pharmacol 2020;177(6):1212-1226 (PMID 31742659)