Silybum marianum is used in traditional Chinese medicine to clear heat and relieve toxic material, to soothe the liver and to promote bile flow. Though its efficacy in treating diseases is still unknown, Silybum marianum is sometimes prescribed by herbalists to help treat liver diseases (cirrhosis, jaundice and hepatitis). Both in vitro and animal research suggest that Silibinin (syn. silybin, sylimarin I) may have hepatoprotective (antihepatotoxic) properties that protect liver cells against toxins.

A 2000 study of such claims by the AHRQ concluded that “clinical efficacy of milk thistle is not clearly established”. A 2005 Cochrane Review considered thirteen randomized clinical trials which assessed milk thistle in 915 patients with alcoholic and/or hepatitis B or C virus liver diseases. They question the beneficial effects of milk thistle for patients with alcoholic and/or hepatitis B or C virus liver diseases and highlight the lack of high-quality evidence to support this intervention. Cochrane concluded that more good-quality randomized clinical trials on milk thistle versus placebo are needed