Seed Silybum marianum

Milk Thistle

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

A thistle whose seed compound silymarin is used for liver support.

Benefits

  • Antioxidant
  • traditionally for liver support

How it's used

  • Capsules and teas

Cautions & interactions

  • Allergy risk for those sensitive to daisies
  • May affect blood sugar and some drug metabolism

Forms & sources

  • Seed extract (silymarin)

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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