Milk thistle (Silybum marianum)


Milk thistle has been used medicinally for over 2,000 years, most commonly for the treatment of liver and gallbladder disorders. Silymarin comes from the seeds of milk thistle and is believed to be the active part of milk thistle. The terms "milk thistle" and "silymarin" are often used interchangeably.
Milk thistle products are popular in Europe and the United States for various types of liver disease. Although numerous human trials have been published, most studies have lacked a strong design and strong conclusive evidence.
Milk thistle has been well tolerated with mild side effects when used in a recommended amount and duration.

Related Terms

Asteraceae, BIO-C®, Bull thistle, cardo blanco, Cardui mariae fructus, Cardui mariae herba, Cardum marianum L., Carduus marianus L., Carsil®, Chardon-Marie, dehydrosilybin, desoxy-silydianin, Emetic root, flavonolignans, Frauendistel, Fructus Silybi mariae, fruit de chardon Marie, heal thistle, Holy thistle, IdB1016®, isosilibinin, isosilybin, isosilybin A, isosilybin B, Kanger, Kocakavkas, kuub, lady's thistle, Legalon®, Legalon® 140, Legalon® Forte, Legalon® SIL, Leviaderm®, Livergol®, Marian thistle, mariana mariana, Mariendistel, Marienkrörner, Mary thistle, mild thistle, milk ipecac, natursil, natursilum, pig leaves, PiùLatte®, royal thistle, S. marianum, St. Mary's thistle, shui fei ji, silibinin, silidianin, Silybi mariae fructus, silybin, silybin A, silybin B, Silybin Meglumine, silybinomer, silybin-phytosome, silybinin, Silybum marianum, Silybum marianum Gaertn, Silybum marianum (L) Gaertn, silychristin, silydianin, silymarin, snake milk, sow thistle, taxifolin, Thisylin®, variegated thistle, Vegicaps®, Venus thistle, wild artichoke.
Select combination products: Iberogast (STW-5; comprised of milk thistle, bitter candy tuft, chamomile flower, peppermint leaves, caraway fruit, licorice root, lemon balm leaves, angelica root, celandine herbs), Phyto-Female Complex (SupHerb, Netanya, Israel; ingredients: standardized extracts of black cohosh, dong quai, milk thistle, red clover, American ginseng, chaste tree berry), Realsil (comprised of silybin, phosphatidylcholine, vitamin E).

evidence table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Cirrhosis (liver scarring) (Grade: B)
Multiple studies from Europe suggest benefits of oral milk thistle for cirrhosis. In studies up to five years long, milk thistle slightly improved liver function and decreased the number of deaths in people with liver disease. Although these results are promising, most studies have been poorly designed. Better research is necessary before a strong conclusion can be made.
Diabetes (type 2) (Grade: B)
Research showed that milk thistle improved control of blood sugar in people with diabetes with and without liver disease. Higher quality research is necessary before strong conclusions can be made.
Diabetic nephropathy (kidney disease) (Grade: B)
Research suggests that silymarin improves blood and urine markers associated with diabetic kidney disease. Further high quality research is needed before a conclusion can be made.
Liver disease (chronic) (Grade: B)
Several studies of milk thistle in liver disease caused by viruses or alcohol report improvements in liver tests. However, most studies have been small and poorly designed. More research is needed before a conclusion can be made.
Acute viral hepatitis (Grade: C)
Existing research shows unclear benefits for the use of milk thistle in acute viral hepatitis, or liver inflammation due to an infection from a virus. Further research is needed to draw conclusions.
Allergic nasal symptoms (Grade: C)
Limited research showed that milk thistle reduced the severity of allergic nasal symptoms. Further study is needed to draw conclusions.
Amanita phalloides mushroom poisoning (Grade: C)
Milk thistle has been used traditionally to treat Amanita phalloides mushroom poisoning. Strong research in humans supporting this use is lacking. Further research is necessary.
Antioxidant (Grade: C)
Early research suggests that milk thistle, alone or given with vitamin E, improves antioxidant status. Although promising, further high quality research is needed before conclusions can be made.
Cancer (Grade: C)
Early evidence reported unclear results for the use of milk thistle in combination with other supplements in people with cancer. One person reported an improvement in liver cancer after taking milk thistle. Further research is needed to draw conclusions.
Fertility (Grade: C)
In women undergoing artificial fertilization (
Heartburn (Grade: C)
An herbal preparation containing milk thistle may be effective in decreasing heartburn. Research of milk thistle alone is necessary for conclusions to be drawn.
High cholesterol (Grade: C)
Although non-human research suggests cholesterol-lowering effects of milk thistle, human studies have provided mixed results. Further studies are necessary before a firm conclusion can be made.
Liver damage from drugs or toxins (Grade: C)
Several studies suggest possible benefits of milk thistle to treat or prevent liver damage caused by drugs or toxic chemicals. Results of this research are unclear, and most studies have been poorly designed. Higher quality trials are necessary to draw conclusions.
Menopause (Grade: C)
An herbal preparation containing milk thistle may be effective in decreasing menopausal symptoms. Research of milk thistle alone is necessary for conclusions to be drawn.
Neurodegenerative disorders (disorders due to neuron destruction) (Grade: C)
In early research, a preparation of milk thistle and other supplements has demonstrated a beneficial effect on people with various neurodegenerative disorders, including multiple sclerosis (MS), Parkinson's disease, and Alzheimer's disease. Further high-quality research with milk thistle alone is needed before any firm conclusions can be made.
Obsessive compulsive disorder (Grade: C)
In human research, milk thistle reduced symptoms of obsessive compulsive disorder (OCD), but lacked benefits compared to regular treatment. Further research is needed to draw conclusions on the benefits of milk thistle in OCD patients.
Osteoarthritis (Grade: C)
Early evidence suggests that milk thistle has anti-inflammatory effects in people with osteoarthritis. Further high quality research is needed before conclusions can be made.
Radiation skin irritation (Grade: C)
Early research in breast cancer patients suggests that silymarin (Levidaerm®) helps ease radiotherapy-induced toxic skin reactions compared to standard care. Further high quality research is warranted.
Beta-thalassemia (genetic blood disorder) (Grade: F)
Human research showed that adding milk thistle to regular therapy lacked further benefits for iron overload in people with beta-thalassemia. Further study is needed before firm conclusions may be made.