St. John's Wort Extract
Also known as: Hypericum perforatum, hypericum extract, St John's wort, hypericin, hyperforin
An extract of the flowering tops of Hypericum perforatum standardized to hypericin and often hyperforin, the most studied botanical for mood. A Cochrane review and a later meta-analysis found that standardized extracts outperformed placebo and matched standard antidepressants in mild to moderate depression with fewer side effects. Its major drawback is pharmacology: hyperforin strongly induces CYP3A4 and P-glycoprotein, reducing levels of many medications, which makes it a high-risk ingredient for multi-ingredient products aimed at broad audiences.
Research summary
Hyperforin inhibits reuptake of serotonin, norepinephrine, dopamine, and GABA, while hypericin and flavonoids contribute additional monoaminergic effects.
Dosage
Daily amounts, of extract.
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| — | 600–900 mg | — | — |
300 mg three times daily with meals, for 600 to 900 mg per day, of an extract standardized to 0.3% hypericin. Mood effects build over four to six weeks. Photosensitivity can occur at higher doses, so advise sun protection in label copy.
Standardization: 0.3% hypericin (often also 3–5% hyperforin)
Source material: flowering top extract
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Bitter, astringent; hypericin is light-sensitive, so use opaque packaging.
Formulation notes
Induces CYP3A4 and P-glycoprotein, lowering levels of oral contraceptives, anticoagulants, immunosuppressants, antiretrovirals, and many other drugs; risk of serotonin syndrome with SSRIs and 5-HTP. Requires a prominent interaction warning and is usually sold as a standalone product.
- Notable drug interactions
- Not for pregnancy
- Restricted in some countries
Sources
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