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3Medicinal

St John's wort

Also sold as Hypericum perforatum

Effective for mild depression, and the single worst herb for drug interactions.

3TrustedSupp Tier System™ · Tier 3Take as a defined course
Check before you startThis one has documented interactions with medication classes where the consequences are serious. If you take any prescription medicine, run it past a pharmacist before starting.

How long to take it

Under medical supervision only, given the interaction profile.

Who it's actually for

Mild to moderate depression — but only after a full medication review.

Safe upper limit

Unverified
No formal limit; 300 mg extract three times daily in trials
It induces liver enzymes that clear a huge range of drugs, silently reducing their effectiveness. Contraceptive failure and transplant rejection have both been documented.
No source attached yet. Treat this as a starting point, not a citation, until reviewed.

Interactions to know about

  • AntidepressantsSSRIs, SNRIs, MAOIs, tricyclics
  • Hormonal contraceptionCombined pill, mini pill, implant, hormonal IUD
  • Blood thinners / antiplateletsWarfarin, apixaban, rivaroxaban, clopidogrel, aspirin
  • ImmunosuppressantsCiclosporin, tacrolimus, azathioprine, biologics, steroids
  • HIV antiretroviralsProtease inhibitors, NNRTIs, integrase inhibitors
  • Chemotherapy / cancer treatmentAny active oncology treatment
  • Any other prescription medicineCatches broad enzyme and absorption effects
  • StatinsAtorvastatin, simvastatin, rosuvastatin

Other supplements:

Run your full list through the interaction check.

Practical notes

  • It can make hormonal contraception fail. This is not theoretical.
  • Never combine with antidepressants — serotonin syndrome is a medical emergency.
  • Tell every prescriber you see that you take it.