Flower Hypericum perforatum

St John's Wort

Written by the VitaWhat editorial team · Medically reviewed by Steve Davis · Last reviewed 19 July 2026 · Editorial policy

A flowering herb studied for low mood — but with many drug interactions.

Benefits

  • Studied for mild-to-moderate low mood

How it's used

  • Standardised extract capsules and teas

Cautions & interactions

  • Major interactions: reduces effect of the pill, warfarin, antidepressants, HIV and transplant drugs
  • Photosensitivity

Forms & sources

  • Flowering tops (standardised to hypericin/hyperforin)

Sources & references

  1. NIH — National Center for Complementary and Integrative Health
  2. Memorial Sloan Kettering — About Herbs

How to read the evidence for botanicals

"Traditionally used for" describes historical use — it is not the same as proven effectiveness. Most botanical products have laboratory or small-trial evidence at best, and few have the large clinical trials that medicines require. In the UK, a Traditional Herbal Registration (THR) mark means a product meets quality standards, not that it has been proven to work.

Before taking any botanical: tell your doctor or pharmacist — herb–drug interactions are common (St John's Wort alone interacts with contraceptives, antidepressants, anticoagulants and transplant medication). Avoid botanicals in pregnancy, while breastfeeding, or alongside prescription medicines unless a clinician has confirmed it is safe.

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