St. John's Wort is one of the best-evidenced plants for easing mild-to-moderate low mood, working about as well as standard antidepressants with milder side effects, plus moderate help for menopausal and premenstrual mood. The decisive issue is safety: it weakens a very wide range of medications and product quality varies widely. (Full Review)
| Marker | Target | Why |
|---|---|---|
| INR (if on warfarin) | Individualized target (often 2.0–3.0) | Detect loss of anticoagulation from enzyme induction |
| Cyclosporine/tacrolimus level (if transplant) | Drug- and protocol-specific therapeutic window | Detect subtherapeutic immunosuppression risking rejection |
| HAM-D or PHQ-9 mood score | Decreasing toward remission (e.g., PHQ-9 <5) | Track antidepressant response and define success |
| Liver enzymes (ALT/AST) | ALT/AST within ~10–30 U/L functional range | Screen for rare hepatic effects on prolonged use |
| Vitamin D / general health panel | 40–60 ng/mL vitamin D | Context for mood and overall health optimization |
Cadence: Mood at 2, 4, and 6 weeks, then every 4–8 weeks while in use; intensify any interacting drug's monitoring when starting and stopping St. John's Wort.