What Is Milk Thistle? What the Research Says and How to Read a Label

Quick answer: Milk thistle is a thistle plant whose seeds are used in traditional herbal preparations, and its main constituent is a mixture called silymarin. Research on its use for liver conditions is mixed and often early, so it should not be treated as a replacement for medical care.

Last updated: 12 October 2026

What is milk thistle?

Milk thistle, also known as Mary thistle or holy thistle, is a plant with purple flowers and white-veined leaves. Its seeds are used to make extracts. NCCIH says the main constituent of milk thistle extract is silymarin, a mixture of compounds, and that historically it was used for liver disorders and to increase breast milk production.

What does the research say?

Research is mixed. A review in American Family Physician concluded that there was insufficient evidence to recommend milk thistle for viral hepatitis and alcohol-related liver disease, and weak evidence for its use as a protective supplement against liver toxins, while noting it appears safe. An evidence report from the US Agency for Healthcare Research and Quality found the evidence was not enough to show whether milk thistle works better for some liver diseases than others, and that it is associated with few, generally minor, adverse effects. That is why GenieHeal does not claim that milk thistle treats or protects the liver.

Safety points

• NCCIH advises talking to your health care provider before using milk thistle if you take any medicine, because some herbs and medicines interact in harmful ways.
• People allergic to plants in the daisy family, such as ragweed and marigold, may react.
• If you are pregnant or breastfeeding, speak to your doctor first.
• If you have a liver condition, ask your doctor before taking any supplement and do not stop prescribed treatment.

See also Can I take herbal supplements with my medication?.

How to read a milk thistle label

1. Look for the Latin name (Silybum marianum or Carduus marianus).
2. Check whether the product states its silymarin content, not just “milk thistle extract”.
3. Read the full ingredient list for other herbs, fillers and allergens.
4. Check the directions and who should not use it.

Milk thistle in GenieHeal Liver Medicine

Milk Thistle (Carduus Marianus) is one of the ingredients in GenieHeal Liver Medicine, alongside Dandelion Extract and Turmeric Root Extract. Liver Medicine is a food supplement, not a medicine, and it is not intended to diagnose, treat, cure or prevent any disease. See our Liver Medicine guide for the full ingredient list and safety information.

Frequently asked questions

Sources

• NCCIH: Milk thistle
• American Family Physician: Milk thistle (2005)
• AHRQ evidence report: Milk thistle effects on liver disease and cirrhosis

Keep reading

• Liver Medicine guide: ingredients and safety information
• Can I take herbal supplements with my medication?
• What is ginger?

Browse all GenieHeal herbal food supplements, learn about GenieHeal, or contact our team.

GenieHeal products are food supplements, not medicines. They are not intended to diagnose, treat, cure or prevent any disease, and they should not replace a varied, balanced diet or medical advice. This article is general information, not medical advice. If you are worried about your health, speak to your GP or pharmacist.