St. John's Wort Dosing for Major Depression
For adults with mild to moderate major depression, use St. John's wort standardized extract (0.3% hypericin) at 300 mg three times daily (900 mg/day total) for 6-12 weeks, or alternatively 600 mg once daily.
Dosing Regimen
Based on the American College of Physicians guidelines and supporting evidence 1:
- Standard dose: 300 mg three times daily (total 900 mg/day)
- Alternative single-dose regimen: 600 mg once daily
- Higher dose for more severe depression: 600 mg twice daily (1200 mg/day total)
- Extract standardization: 0.12% to 0.3% hypericin content
- Treatment duration: 6-12 weeks minimum to assess response
The evidence shows that dosages in clinical trials ranged from 300 mg/day to 1800 mg/day 1, with most effective studies using 900-1200 mg/day. Research specifically demonstrates that both 600 mg/day (single dose) and 1200 mg/day (600 mg twice daily) are safe and effective, with the higher dose showing more patients achieving remission 2.
Clinical Efficacy Context
St. John's wort demonstrates comparable efficacy to second-generation antidepressants for mild to moderate depression 3. Meta-analyses show similar response rates (52% vs 54%) and remission rates (30% vs 36%) compared to SSRIs, but with significantly better tolerability—patients have lower discontinuation rates (12% vs 16%) and fewer adverse events (4% vs 7%) 1.
Critical Safety Warnings
Absolute Contraindications
- Do not combine with MAO inhibitors or serotonin reuptake inhibitors (serotonin syndrome risk) 3
- Avoid in patients taking oral contraceptives (reduced efficacy due to CYP3A4 induction) 3
- Contraindicated with immunosuppressants (reduced drug levels) 3
Drug Interactions
St. John's wort is a potent CYP3A4 inducer 3. It reduces bioavailability of numerous medications including anticoagulants, antiretrovirals, chemotherapy agents, and cardiovascular drugs. The hyperforin component drives these interactions—products with <1 mg hyperforin daily minimize interaction risk 4.
Photosensitivity Risk
Hypericin causes photosensitivity 5, 6. Patients must avoid UVA phototherapy and excessive sun exposure during treatment. Studies show St. John's wort lowers the minimal erythema dose to UVA1 irradiation 6.
Important Caveats
Quality control is a major concern: St. John's wort is not FDA-regulated in the United States, meaning no standardization exists for contents and potency 3. Patients may not reliably obtain preparations with similar effectiveness to those used in clinical trials. Some formulations have been found to contain undisclosed corticosteroids 5.
Limited evidence for severe depression: The trials predominantly enrolled patients with mild to moderate depression 1. Evidence for severe depression is insufficient, though some data suggests higher doses (600 mg three times daily) may be needed 7.
Pregnancy and lactation: Safety is unknown 5. St. John's wort affects placental calcium transport 8, raising concerns about use during pregnancy.
Common Adverse Effects
Mild and generally well-tolerated 3:
- Gastrointestinal symptoms (most common)
- Dizziness or confusion
- Fatigue or sedation
- Skin reactions
- Restlessness
- Headache
- Dry mouth
These occur at significantly lower rates than with SSRIs 1.
Practical Implementation
Start with 300 mg three times daily with meals to minimize GI upset. If adherence is a concern, use 600 mg once daily. For patients not responding after 6 weeks, consider increasing to 600 mg twice daily (1200 mg/day total) 2. Ensure the product is standardized to 0.3% hypericin content. Screen thoroughly for all medications and supplements before initiating treatment due to extensive drug interactions 3.