Milk thistle is widely used in the treatment of viral hepatitis (particularly hepatitis C). But studies show mixed results. Some found improvements in liver function, while others did not. None of the studies compared milk thistle with interferon or other medications for viral hepatitis.
Based on traditional use, milk thistle has been used as an emergency antidote to poisoning by deathcap mushroom (Amanita phalloides). Animal studies have found that milk thistle extract completely counteracts the toxic effects of the mushroom when given within 10 minutes of ingestion. If given within 24 hours, it significantly reduces the risk of liver damage and death.
Early laboratory studies also suggest that silymarin and other active substances in milk thistle may have anti-cancer effects. These substances appear to stop cancer cells from dividing and reproducing, shorten their life span, and reduce blood supple to tumors. More studies are needed, however, to show whether milk thistle has any effects in the body (not just test tubes).