Milk Thistle

Milk Thistle

Common Names

  • Holy thistle
  • Lady's thistle
  • Mary thistle
  • Marian thistle

For Patients & Caregivers

Milk thistle and compounds derived from it are commonly used as herbal supplements for liver problems, but study results are mixed.

Laboratory studies suggest that milk thistle or some of its compounds have protective effects on the liver, but other animal studies suggest negative effects when combined with chronic alcohol consumption.

Studies in humans are mixed, and both a large survey and multicenter trial among patients with chronic hepatitis C did not find benefit on liver function tests with milk thistle. More study is needed to determine or confirm the circumstances under which milk thistle or its compounds might be helpful.

  • To treat alcohol-induced liver damage or cirrhosis
    Some placebo-controlled trials suggest silymarin may be helpful in treating alcoholic liver disease or cirrhosis, but more study is needed.
  • To treat hepatitis
    A large survey and multicenter trial among patients with chronic hepatitis C did not find benefit on liver function tests with milk thistle. 
  • To prevent and treat drug-induced liver damage
    Laboratory, animal, and clinical trials suggest this use, although the effect varies by drug.
  • You are taking cytochrome P450 3A4 substrate drugs: Milk thistle may increase the risk of side effects of these drugs.
  • You are taking UGT (Uridine 5’-diphospho-glucuronosyltransferase) substrate drugs: Milk thistle may increase the risk of side effects of these drugs.
  • You are taking sirolimus: Milk thistle may interfere with the clearance of this drug.

High doses of silibinin can elevate bilirubin and liver enzymes.

Case reports
GI symptoms: 
A patient experienced episodes of sweating, nausea, vomiting, diarrhea, abdominal pain, weakness, and collapse. Symptoms resolved after the patient discontinued use of milk thistle.
Severe nosebleed: In a 25-year-old man, which may have been due to self-medication with aspirin, garlic, and milk thistle. His symptoms improved following treatment.

  • Patients with diabetes should consult their healthcare professionals, as some studies suggest milk thistle compounds may also lower blood sugar levels.

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For Healthcare Professionals

Silybum marianum, Carduus marianum

Derived from the seed, pod, or fruit of milk thistle, the flavolignan silymarin is used primarily to manage various liver diseases. In vitro and animal studies suggest that flavonoids in milk thistle have antioxidant and anticancer effects (7) (8) (12) (16) (17), and may protect against Alzheimer’s disease (23) (24).

In humans, data suggest benefits with milk thistle or silymarin supplementation to improve lipid profiles and glycemic indices in type 2 diabetic patients (18) (40). Some placebo-controlled trials suggest silymarin may be helpful in alcoholic liver disease (9) or cirrhosis (11) (19), or to improve fibrosis associated with nonalcoholic steatohepatitis (39). However, in both a large survey and subsequent multicenter placebo-controlled trial among patients with chronic hepatitis C, silymarin did not significantly reduce serum ALT levels (41) (42). In addition, although silymarin was associated with reduced progression from fibrosis to cirrhosis, no impact on clinical outcomes was observed  (43).

Other studies suggest milk thistle may reduce chemotherapy-induced hepatotoxicity in children with acute lymphoblastic leukemia (20) and cisplatin-induced nephrotoxicity (28), or improve capecitabine-induced hand-foot syndrome (6) and radiation therapy-induced mucositis (3).

Animal studies show that silymarin has estrogenic activity with mild proliferative effects in rat uteri (27), and that the compound silibinin can exacerbate the negative effects of chronic alcohol consumption on liver cancer (10). Therefore, more study is needed to determine or confirm the circumstances under which milk thistle or its compounds may be helpful.

  • Cancer prevention
  • Cirrhosis
  • Drug-induced hepatotoxicity
  • Hepatitis
  • Liver disease

Animal models suggest that silymarin from milk thistle confers hepatoprotection via downregulation of extracellular matrix proteins such as collagen (2). It may also be useful against liver carcinogenesis by inhibiting mast cells, a source of matrix metalloproteins that are involved in invasion and angiogenesis (29). In addition, silymarin reduced cisplatin-induced kidney damage in rats without diminishing the drug’s antitumor activity (7), and suppressed formation of amyloid beta-proteins and neurotoxicity in mice (30).

Silibinin, one of the flavonoids, demonstrated antioxidant and anti-inflammatory effects by inhibiting release of hydrogen peroxide and production of tumor necrosis factor alpha (31). Another study showed improvement in endothelial dysfunction via reduction in circulating and vascular asymmetric dimethylarginine (ADMA) levels. ADMA is an endogenous inhibitor of nitric oxide synthase (NOS) and is believed to play a role in endothelial dysfunction, associated with cardiovascular disease (32). Silibinin also inhibits the early phase of hepatitis C viral infection by affecting endosomal trafficking of virions (34).

Other studies indicate milk thistle flavonoids exert anticancer effects by arresting G1 and S phases of the cell cycle (8). Silybin inhibited hepatocellular carcinoma cell growth via the Notch signaling pathway (36). Silibinin suppressed the epidermal growth factor receptor (EGFR)-induced expression of CD44, the transmembrane receptor for hyaluronan implicated in tumor cell invasion and metastasis by inhibiting EGFR activity in breast cancer cells (33). Suggested mechanisms for reduced efficacy of silibinin in liver tumor-bearing animals that were co-administered ethanol include impaired hepatic processing of silibinin (10).

Silybin and isosilybin were shown to strongly inhibit PXR-mediated CYP3A4 induction (35).

High doses of silibinin can elevate bilirubin and liver enzymes (25).

Case reports
Intermittent GI symptoms: 
A patient experienced intermittent episodes of sweating, nausea, vomiting, diarrhea, abdominal pain, weakness, and collapse that resolved after discontinuation of milk thistle supplementation (5).
Severe epistaxis: In a 25-year-old man, possibly due to self-medication with aspirin, garlic, and milk thistle. His symptoms improved following treatment  (22).
 

  • Cytochrome P450 3A4 substrates: Milk thistle inhibits cytochrome P450 3A4 (4) and can affect the intracellular concentration of drugs metabolized by this enzyme. However, conflicting data indicate no such effects (13) (14) (38). In another study, consumption of milk thistle did not reduce levels of indinavir, an AIDS drug (15).
  • UGT (Uridine 5’-diphospho-glucuronosyltransferase) substrates: Milk thistle modulates UGT enzymes in vitro and can increase the side effects of drugs metabolized by them (26).
  • Sirolimus: Milk thistle may decrease clearance. Monitor therapy especially when combined with nivolumab, which may interfere with the potential to help prevent rejection of donor kidney in transplant patients (44) (45).

  1. Bissett N, et al. Herbal Drugs and Phytopharmaceuticals. New York: Medpharm, CRC Press; 1994.

  2. Chen IS, Chen YC, Chou CH, et al. Hepatoprotection of silymarin against thioacetamide-induced chronic liver fibrosis. J Sci Food Agric. 2012 May;92(7):1441-7.

  3. Adverse Drug Reactions Advisory Committee. An adverse reaction to the herbal medication milk thistle (Silybum marianum). Med J Aust. 1999;170:218-9.

  4. Elyasi S, Shojaee FSR, Allahyari A, et al. Topical Silymarin Administration for Prevention of Capecitabine-Induced Hand-Foot Syndrome: A Randomized, Double-Blinded, Placebo-Controlled Clinical Trial. Phytother Res. 2017 Sep;31(9):1323-1329. doi: 10.1002/ptr.5857.

  5. Brandon-Warner E, Eheim AL, Foureau DM, et al. Silibinin (Milk Thistle) potentiates ethanol-dependent hepatocellular carcinoma progression in male mice. Cancer Lett. Dec 29 2012;326(1):88-95.

  6. Thelen P, Wuttke W, Jarry H, Grzmil M, Ringert RH. Inhibition of telomerase activity and secretion of prostate specific antigen by silibinin in prostate cancer cells. J Urol. 2004 May;171(5):1934-8.

  7. Fuhr U, Beckmann-Knopp S, Jetter A, et al. The effect of silymarin on oral nifedipine pharmacokinetics. Planta Med. 2007;73(14):1429-35.

  8. Mills E, Wilson K, Clarke M, et al. Milk thistle and indinavir: a randomized controlled pharmacokinetics study and meta-analysis. Eur J Clin Pharmacol. 2005;61(1):1-7.

  9. Ramasamy K and Agarwal R. Multitargeted therapy of cancer by silymarin. Cancer Lett. 2008 Oct 8;269(2):352-62.

  10. Saller R, Brignoli R, Melzer J, Meier R. An updated systematic review with meta-analysis for the clinical evidence of silymarin.Forsch Komplementmed 2008;15(1):9-20.

  11. Shakeel M, Trinidade A, McCluney N, Clive B. Complementary and alternative medicine in epistaxis: a point worth considering during the patient’s history. Eur J Emerg Med. 2010 Feb;17(1):17-9.

  12. Murata N, Murakami K, Ozawa Y, et al. Silymarin attenuated the amyloid β plaque burden and improved behavioral abnormalities in an Alzheimer’s disease mouse model. Biosci Biotechnol Biochem. 2010 Nov 23;74(11):2299-306.

  13. Yin F, Liu J, Ji X, et al. Silibinin: A novel inhibitor of Aβ aggregation. Neurochem Int. 2011 Feb;58(3):399-403. 

  14. Flaig TW, Gustafson DL, Su LJ, et al. A phase I and pharmacokinetic study of silybin-phytosome in prostate cancer patients. Invest New Drugs. 2007 Apr;25(2):139-46.

  15. Ninsontia C, Pongjit K, Chaotham C, Chanvorachote P. Silymarin selectively protects human renal cells from cisplatin-induced cell death. Pharm Biol. 2011 Oct;49(10):1082-90.

  16. Ramakrishnan G, Jagan S, Kamaraj S, Anandakumar P, Devaki T.  Silymarin attenuated mast cell recruitment thereby decreased the expressions of matrix metalloproteinases-2 and 9 in rat liver carcinogenesis. Invest New Drugs. 2009 Jun;27(3):233-40.

  17. Murata N, Murakami K, Ozawa Y, et al. Silymarin attenuated the amyloid β plaque burden and improved behavioral abnormalities in an Alzheimer’s disease mouse model. Biosci Biotechnol Biochem. 2010;74(11):2299-306.

  18. Bannwart CF, Peraçoli JC, Nakaira-Takahagi E, Peraçoli MT. Inhibitory effect of silibinin on tumour necrosis factor-alpha and hydrogen peroxide production by human monocytes. Nat Prod Res. 2010 Nov;24(18):1747-57.

  19. Li Volti G, Salomone S, Sorrenti V, et al. Effect of silibinin on endothelial dysfunction and ADMA levels in obese diabetic mice. Cardiovasc Diabetol. 2011 Jul 14;10:62.

  20. Blaising J, Lévy PL, Gondeau C, et al. Silibinin inhibits hepatitis C virus entry into hepatocytes by hindering clathrin-dependent trafficking. Cell Microbiol. Cell Microbiol. 2013 Nov;15(11):1866-82.

  21. Mooiman KD, Maas-Bakker RF, Moret EE, et al. Milk Thistle’s Active Components Silybin and Isosilybin: Novel Inhibitors of PXR-mediated CYP3A4 Induction. Drug Metab Dispos. 2013 Aug;41(8):1494-504.

  22. Abenavoli L, Capasso R, Milic N, Capasso F. Milk thistle in liver diseases: past, present, future. Phytother Res. 2010 Oct;24(10):1423-32.

  23. Kawaguchi-Suzuki M, Frye RF, Zhu HJ, et al. The Effects of Milk Thistle (Silybum marianum) on Human Cytochrome P450 Activity. Drug Metab Dispos. 2014 Oct;42(10):1611-6.

  24. Wah Kheong C, Nik Mustapha NR, Mahadeva S. A Randomized Trial of Silymarin for the Treatment of Nonalcoholic Steatohepatitis. Clin Gastroenterol Hepatol. Dec 2017;15(12):1940-1949.e1948.

  25. Freedman ND, Curto TM, Morishima C, et al. Silymarin use and liver disease progression in the Hepatitis C Antiviral Long-Term Treatment against Cirrhosis trial. Aliment Pharmacol Ther. Jan 2011;33(1):127-137.

  26. Jiao Z, Shi XJ, Li ZD, et al. Population pharmacokinetics of sirolimus in de novo Chinese adult renal transplant patients. Br J Clin Pharmacol. Jul 2009;68(1):47-60.

  27. Barnett R, Barta VS, Jhaveri KD. Preserved Renal-Allograft Function and the PD-1 Pathway Inhibitor Nivolumab. N Engl J Med. Jan 12 2017;376(2):191-192.

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