Why People Take St. John's Wort
People primarily take St. John's wort (Hypericum perforatum) to treat mild-to-moderate major depressive disorder, where it demonstrates efficacy comparable to second-generation antidepressants but with better tolerability. 1
Primary Therapeutic Indication: Depression
St. John's wort has established clinical evidence for treating major depressive disorder (MDD). Low-quality evidence shows it may be as effective as second-generation antidepressants (SGAs) for treating MDD, while moderate-quality evidence demonstrates it is better tolerated than SGAs 1. Meta-analyses of 9 trials involving 1,513 participants showed similar response rates between St. John's wort and SGAs (54% vs. 52%) after 6-12 weeks of treatment 2. Patients treated with St. John's wort had significantly lower discontinuation rates due to adverse events (4% vs. 7%) compared to those on antidepressants 2.
The typical dosing ranges from 300 mg/d to 1,800 mg/d, using standardized extracts (most commonly 0.12% to 0.28% hypericin) 2. The active constituents hypericin and hyperforin are believed responsible for the antidepressant effects 3, 4.
Secondary Therapeutic Uses
Beyond depression, people use St. John's wort for:
- Menopausal symptoms: Clinical evidence supports efficacy comparable to standard treatments 3
- Wound healing: Traditional use supported by preclinical evidence showing enhanced collagen deposition, reduced inflammation, and accelerated epithelialization 5
- Anxiety disorders: Historical use in traditional medicine systems, though clinical evidence remains limited 6, 7
Critical Safety Considerations
St. John's wort induces cytochrome P450 3A4 (CYP3A4), creating dangerous drug-drug interactions 1, 8, 1. It may reduce bioavailability or efficacy of:
- Oral contraceptives
- Immunosuppressants
- Many other medications metabolized by CYP3A4
It is contraindicated in patients receiving:
- Monoamine oxidase inhibitors
- Serotonin reuptake inhibitors (risk of serotonin syndrome) 1
For perioperative patients, St. John's wort should be held for 2 weeks before surgery due to multiple constituents with long half-lives and CYP3A4 induction effects 8.
Important Caveats
The FDA does not regulate St. John's wort, meaning no quality control standards exist for contents and potency 1. Patients in the United States may not reliably obtain preparations with similar effectiveness to those used in clinical studies 1.
Common adverse effects include gastrointestinal symptoms, skin reactions, fatigue, sedation, restlessness, dizziness, headache, and dry mouth—though these occur less frequently than with SGAs 1.
The strongest evidence supports use specifically for mild-to-moderate depression in patients without contraindications and who are not taking interacting medications. Most other pharmacological activities (neuroprotective, anticancer, antiviral, antimicrobial) remain preclinical without robust clinical validation 3.