Milk thistle

Also known as silymarin, silybum marianum, milk thisle.

Last reviewed October 9, 2026 · Jump to references

What is Milk thistle?

In plain words

Milk thistle is a plant whose extracts contain a group of substances called silymarin. The body absorbs only a small amount of these substances and breaks them down, mainly in the liver. Researchers study milk thistle for possible effects on liver health. Human studies have not clearly shown that it treats liver disease, and it can cause stomach upset or allergic reactions.

Technical definition

Milk thistle (Silybum marianum) is a botanical whose fruits contain silymarin, a mixture of flavonolignans that includes silybin (silibinin). Silymarin has no single established receptor target; laboratory studies describe antioxidant effects and modulation of inflammatory signaling, while oral absorption is limited and its constituents undergo extensive metabolism. Milk thistle is marketed as a dietary supplement in the United States and is not FDA-approved to treat liver disease.

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Evidence by use

Each use is rated on its own. There is no single overall effectiveness score.