Milk Thistle

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Milk Thistle
  Evaluated for:
Effectiveness Rating Effectiveness Rating
Non-alcoholic liver disease
+1 (Slight Evidence)
Acute viral hepatitis
-1 (Possibly Ineffective)


  • Silymarin is a flavonoid complex extracted from the seeds of milk thistle. It is used in the treatment and/or prevention of liver disease. The terms silymarin and milk thistle are often used interchangeably.
  • There is preliminary evidence that silymarin may reduce liver enzyme levels, improve liver histology, and improve survival in patients with non-viral cirrhosis or chronic liver disease. Many liver-protective mechanisms have been proposed, but the actual mechanism is not known.
  • Milk thistle has been used as an antidote for mushroom poisoning (Amanita phalloides) despite that there are no controlled studies to prove its efficacy.
  • Milk thistle dietary supplements are often standardized to contain 70 to 80% silymarin. Dosing ranges from 160 to 800 mg per day for liver damage.
  • Milk thistle is generally considered safe and well tolerated for up to 6 years when taken within the recommended dose range.


  • Adverse reactions to milk thistle consist primarily of mild gastrointestinal distress (nausea, heartburn, diarrhea, flatulence, and/or loss of appetite), itching and headache. Rare cases have been reported of anaphylaxis, a severe and life-threatening allergic reaction that is a known risk with many vegetables.
  • Individuals with known sensitivity to milk thistle and other members of the Aster family (e.g., artichokes, thistle, kiwi) should certainly avoid it. On the other hand, research has shown good tolerance to milk thistle for up to six years.
  • Because milk thistle is metabolized by the cytochrome P450 liver pathway, patients already taking other cytochrome-P450-metabolized medications should use extreme caution. If you take any prescribed medications, consult your doctor prior to using milk thistle.
  • Milk thistle may cause or worsen iron deficiency in individuals already at risk. It has been used in combination with an agent called desferrioxamine to facilitate excretion of excess iron from individuals with potentially toxic levels. Unfortunately, this very benefit can have the opposite effect and reduce iron levels in patients whose levels are already too low.
  • Although several studies have suggested that milk thistle may prevent or treat liver damage, the results are unclear and the studies available were not well designed. There is, therefore, insufficient scientific evidence to recommend milk thistle for this use.

DOSAGE:Milk thistle dietary supplements are often standardized to contain 70 to 80% silymarin. Dosing ranges from 160 to 800 mg per day for liver damage.

CONCLUSION: If you elect to try Milk Thistle, remember to include it in your list of medications when you visit your doctor and other health care providers.

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