Milk thistle
Silybum marianum
Herbs & Roots. Western & European.
Also called St. Mary's thistle, Lady's thistle, Holy thistle, Silymarin
Spanish: Cardo mariano
May affect liver-cleared medicinesMilk thistle is a spiny plant whose seeds contain silymarin, a mix studied mainly for liver disease.
Did you know? The white veins on milk thistle leaves are said, in an old legend, to be drops of milk from the Virgin Mary.
What it may help, and how strong the proof is
- Liver. Trials in liver disease are small and mixed. Pooled data in cirrhosis show fewer liver-related deaths, but not clearly fewer deaths overall.Early proof
- Infections. Tested for hepatitis C in human trials without clear benefit.Not supported
- Cleansing & detox. Sold as a liver cleanse, and there is no good evidence for that claim.Not supported
Parts of the body
Traditional use
European herbalists used milk thistle for centuries for liver and gallbladder complaints. Modern use is mostly as a seed extract supplement.
How it is classified
- Herbal actions
- Hepatic, Antioxidant, Anti-inflammatory. Energy: neutral.
How people take it
Most studies used silymarin extract capsules, often several hundred milligrams a day. Seed tea is weaker, because silymarin dissolves poorly in water.
Capsule, tablet, tea and tincture.
Where to get it
Comes from the seeds of a spiny plant native to the Mediterranean that now grows widely in North America. Sold as seed extract capsules, tablets, and tinctures.
Be careful
Can cause mild stomach upset, bloating, or diarrhea. Allergic reactions are possible in people sensitive to the daisy family. It may change how the liver clears some medicines.
Avoid if: ragweed allergy; pregnancy.
Mixing with other things
- Works well together
Common together in liver-support teas and products.
- Works well together
Often combined in liver support products.
- Worth knowingImmune-suppressing medicine (transplant drugs, some arthritis drugs)
Can slow some liver enzymes that clear medicines, so levels of immune-suppressing drugs could change.
- Worth knowingBlood thinners (warfarin, Eliquis, Xarelto, Plavix, daily aspirin)
May change how the liver clears some blood thinners, and the effect is not well studied.
The honest take
Milk thistle is one of the most studied liver herbs, but its results are still mixed. Some trials show better liver numbers, and pooled data show fewer liver deaths in cirrhosis, but clear survival gains are not proven. Claims that it cleanses the liver or helps hepatitis C are not supported.