Herb & supplement monograph

Milk Thistle Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by ·Updated July 2026
What is this page for?

First and foremost: how Milk Thistle interacts with medications. The heart of this page is the interaction list — every drug Milk Thistle is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Milk Thistle is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Milk Thistle Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Milk Thistle drug interaction appears low for most people. None of the listed interactions are rated major, and the great majority are minor, with a smaller group rated moderate.

Interactions deserving the most attention

The combinations with the best human data deserve the most care. Milk thistle can lower blood sugar, so people taking diabetes medications could see an added glucose-lowering effect. It may also slow the body's clearance of sirolimus, a transplant drug where levels are watched closely, though this was seen in patients with liver impairment. One case report links milk thistle to a raised INR with warfarin, so anyone on this blood thinner should be aware. Possible effects on tamoxifen, morphine, and some hepatitis C drugs come from animal or lab research only.

What the rest of the list means

A long list of interacting medications does not mean each combination is harmful. Most entries here are theoretical, based on lab findings that milk thistle might affect enzymes or transporters the body uses to clear certain drugs. In several cases, human studies found the predicted effect did not cause meaningful changes.

Check your medications against Milk Thistle

Based on HelloPharmacist’s Milk Thistle interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Milk Thistle

954 medications have a known interaction with Milk Thistle, graded by severity. Select any drug for the full evidence-based detail.

2,830 drugs
AcarboseGlucobay, Prandase, Precose
Moderate Antidiabetes Drugs

Taking milk thistle with antidiabetes drugs may increase the risk of hypoglycemia.

Read the full Milk Thistle + Acarbose interaction Acarbose drug page: uses, dosage & side effects
AcetaminophenChildren's Tylenol, Children's Tylenol Meltaways, Tylenol, Tylenol Ex Strength
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen interaction Acetaminophen drug page: uses, dosage & side effects
Acetaminophen, AspirinGemnisyn
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Aspirin interaction
Acetaminophen, Aspirin, CaffeineExcedrin, Excedrin Extra Strength, Excedrin Migraine
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Aspirin, Caffeine interaction
Acetaminophen, Brompheniramine, PhenylpropanolamineDimetapp Cold and Flu
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Brompheniramine, Phenylpropanolamine interaction
Acetaminophen, ButalbitalAxocet, Bancap, Bucet, Butex Forte, Esgic CF, Orbivan CF +5 more
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Butalbital interaction
Acetaminophen, Butalbital, CaffeineEsgic, Esgic Plus, Fiogesic, Fioricet, Repan, Tecnal +1 more
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Butalbital, Caffeine interaction Acetaminophen, Butalbital, Caffeine drug page: uses, dosage & side effects
Acetaminophen, Butalbital, Caffeine, CodeineEsgic with Codeine, Fioricet w/ Codeine
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Butalbital, Caffeine, Codeine interaction
Acetaminophen, Butalbital, CodeineBancap w/ Codeine
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Butalbital, Codeine interaction
Acetaminophen, Butalbital, Codeine PhosphatePhrenilin #3
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Butalbital, Codeine Phosphate interaction
Acetaminophen, Caffeine, Chlorpheniramine, Hydrocodone, PhenylephrineHycomine Compound
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Caffeine, Chlorpheniramine, Hydrocodone, Phenylephrine interaction
Acetaminophen, Caffeine, CodeineGesic C15, Gesic C30, Gesic C8, Lenoltec 1, Lenoltec 2, Lenoltec 3 +1 more
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Caffeine, Codeine interaction
Acetaminophen, Caffeine, Codeine, SalicylamideCodalan No.1, Codalan No.2, Codalan No.3
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Caffeine, Codeine, Salicylamide interaction
Acetaminophen, Caffeine, DihydrocodeineDHC Plus, Panlor DC, Panlor SS
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Caffeine, Dihydrocodeine interaction
Acetaminophen, Caffeine, IsomethepteneMigralam
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Caffeine, Isometheptene interaction
Acetaminophen, Caffeine, PyrilamineMidol Max Strength Menstrual
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Caffeine, Pyrilamine interaction
Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HbrVicks Formula 44M Cough, Cold & Flu Relief
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan Hbr interaction
Acetaminophen, Chlorpheniramine, Codeine, PhenylephrineColrex
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine interaction
Acetaminophen, Chlorpheniramine, DextromethorphanCoricidin II Extra Strength Cold and Flu
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Dextromethorphan interaction
Acetaminophen, Chlorpheniramine, Dextromethorphan HydrobromideCoricidin HBP Maximum Strength Flu
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Dextromethorphan Hydrobromide interaction
Acetaminophen, Chlorpheniramine, Dextromethorphan, PhenylpropanolamineMulti Symptom Cold Relief
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Dextromethorphan, Phenylpropanolamine interaction
Acetaminophen, Chlorpheniramine, Dextromethorphan, PseudoephedrineChildren's Tylenol Cold Plus Cough, Tylenol Cold Ex Strength
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Dextromethorphan, Pseudoephedrine interaction
Acetaminophen, Chlorpheniramine, Guaifenesin, Phenylephrine, SalicylamideRhinogesic GG
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Guaifenesin, Phenylephrine, Salicylamide interaction
Acetaminophen, Chlorpheniramine, PhenylephrineAlka-Seltzer PLUS, Histex SR, Protid
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Phenylephrine interaction
Acetaminophen, Chlorpheniramine, Phenylephrine, SalicylamideRhinogesic, Rhinogesic JR
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Phenylephrine, Salicylamide interaction
Acetaminophen, Chlorpheniramine, PhenylpropanolamineAlumadrine, Conex, Sinadrin Max Strength, Sinulin
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Phenylpropanolamine interaction
Acetaminophen, Chlorpheniramine, Phenylpropanolamine, OpiumHista-Derfule
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Phenylpropanolamine, Opium interaction
Acetaminophen, Chlorpheniramine, Phenylpropanolamine, PhenyltoloxamineNorel Plus
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Phenylpropanolamine, Phenyltoloxamine interaction
Acetaminophen, Chlorpheniramine, PseudoephedrineAlka-Seltzer PLUS Liquid Gels, Children's Tylenol Cold, Codimal, Comtrex, Extra Strength Tylenol Allergy Sinus, Lorsin +3 more
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorpheniramine, Pseudoephedrine interaction
Acetaminophen, ChlorzoxazoneAcetazone Forte, Extra Strength Tylenol Aches & Strains, Parafon Forte
Moderate Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.

Read the full Milk Thistle + Acetaminophen, Chlorzoxazone interaction
Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Milk Thistle combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
The big picture

The kinds of drugs Milk Thistle affects

Every type of medication (drug category) Milk Thistle is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 17 drug categories Milk Thistle interacts with
Antidiabetes DrugsCytochrome P450 2b6 (cyp2b6) SubstratesGlucuronidated DrugsLedipasvirMorphineRaloxifene (evista)Sirolimus (rapamune)Sofosbuvir (solvaldi)Tamoxifen (nolvadex)Warfarin (coumadin)Cytochrome P450 2c9 (cyp2c9) SubstratesCytochrome P450 3a4 (cyp3a4) SubstratesEstrogensHmg-coa Reductase Inhibitors ("statins")Indinavir (crixivan)Organic Anion-transporting Polypeptide Substrates (oatp)P-glycoprotein Substrates
Antidiabetes Drugs

Taking milk thistle with antidiabetes drugs may increase the risk of hypoglycemia.
Clinical research shows that milk thistle extract, alone or along with tree turmeric extract, can lower blood glucose levels and glycated hemoglobin (HbA1c) in patients with type 2 diabetes, including those already taking antidiabetes drugs. Additionally, animal research shows that milk thistle extract increases the metformin maximum plasma concentration and area under the curve and decreases the renal clearance of metformin, due to inhibition of the multi-drug and toxin extrusion protein 1 (MATE1) renal tubular transport protein.

Likelihood Possible Evidence B
Cytochrome P450 2B6 (Cyp2B6) Substrates

Theoretically, milk thistle might inhibit CYP2B6.
An in vitro study shows that silybin, a constituent of milk thistle, binds to and noncompetitively inhibits CYP2B6. Additionally, silybin might downregulate the expression of CYP2B6 by decreasing mRNA and protein levels.

Likelihood Possible Evidence D
Glucuronidated Drugs

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.
Laboratory research shows that milk thistle constituents inhibit uridine diphosphoglucuronosyl transferase (UGT), the major phase 2 enzyme that is responsible for glucuronidation. Theoretically, this could decrease the clearance and increase levels of glucuronidated drugs. Other laboratory research suggests that a milk thistle extract of silymarin might inhibit beta-glucuronidase, although the significance of this effect is unclear.

Likelihood Possible Evidence D
Ledipasvir

Theoretically, milk thistle might increase the levels and clinical effects of ledipasvir.
Animal research in rats shows that milk thistle increases the area under the curve (AUC) for ledipasvir and slows its elimination.

Likelihood Possible Evidence D
Morphine

Theoretically, concomitant use of milk thistle with morphine might affect serum levels of morphine and either increase or decrease its effects.
Animal research shows that milk thistle reduces serum levels of morphine by up to 66%. In contrast, laboratory research shows that milk thistle constituents inhibit uridine diphosphoglucuronosyl transferase (UGT), the major phase 2 enzyme that is responsible for glucuronidation. Theoretically, this could decrease the clearance and increase morphine levels. The effect of taking milk thistle on morphine metabolism in humans is not known.

Likelihood Possible Evidence D
Raloxifene (Evista)

Theoretically, milk thistle might decrease the clearance and increase levels of raloxifene.
Laboratory research suggests that the milk thistle constituents silibinin and silymarin inhibit the glucuronidation of raloxifene in the intestines.

Likelihood Possible Evidence D
Sirolimus (Rapamune)

Milk thistle might decrease the clearance of sirolimus.
Pharmacokinetic research shows that a milk thistle extract of silymarin decreases the apparent clearance of sirolimus in hepatically impaired renal transplant patients. It is unclear if this interaction occurs in patients without hepatic impairment.

Likelihood Possible Evidence B
Sofosbuvir (Solvaldi)

Theoretically, milk thistle might decrease the levels and clinical effects of sofosbuvir.
Animal research in rats shows that milk thistle reduces the metabolism of sofosbuvir, as well as the hepatic uptake of its active metabolite.

Likelihood Possible Evidence D
Tamoxifen (Nolvadex)

Theoretically, the milk thistle constituent silibinin might increase tamoxifen levels and interfere with its conversion to an active metabolite.
Animal research suggests that the milk thistle constituent silibinin might increase plasma levels of tamoxifen and alter its conversion to an active metabolite. The mechanism appears to involve inhibition of pre-systemic metabolism of tamoxifen by cytochrome P450 (CYP) 2C9 and CYP3A4, and inhibition of P-glycoprotein-mediated efflux of tamoxifen into the intestine for excretion. Whether this interaction occurs in humans is not known.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, milk thistle might increase the effects of warfarin.
In one case report, a man stabilized on warfarin experienced an increase in INR from 2.64 to 4.12 after taking a combination product containing milk thistle 200 mg daily, as well as dandelion, wild yam, niacinamide, and vitamin B12. Levels returned to normal after stopping the supplement. Although a direct correlation between milk thistle and the change in INR cannot be confirmed, some in vitro research suggests that milk thistle might inhibit cytochrome P450 2C9 (CYP2C9), an enzyme involved in the metabolism of various drugs, including warfarin.

Likelihood Possible Evidence D
Cytochrome P450 2C9 (Cyp2C9) Substrates

It is unclear if milk thistle inhibits CYP2C9; research is conflicting.
In vitro research suggests that milk thistle might inhibit CYP2C9. Additionally, 3 case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking milk thistle and cancer medications that are CYP2C9 substrates, including imatinib and capecitabine. However, contradictory clinical research shows that milk thistle extract does not inhibit CYP2C9 or significantly affect levels of the CYP2C9 substrate tolbutamide. Differences in results could be due to differences in dosages or formulations utilized.

Likelihood Unlikely Evidence B
Cytochrome P450 3A4 (Cyp3A4) Substrates

It is unclear if milk thistle inhibits CYP3A4; research is conflicting.
While laboratory research shows conflicting results, pharmacokinetic research shows that taking milk thistle extract 420-1350 mg daily does not significantly affect the metabolism of the CYP3A4 substrates irinotecan, midazolam, or indinavir. However, 8 case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking milk thistle and cancer medications that are CYP3A4 substrates, including gefitinib, sorafenib, doxorubicin, and vincristine.

Likelihood Unlikely Evidence D
Estrogens

Theoretically, milk thistle might interfere with estrogen therapy through competition for estrogen receptors.
Animal research suggests that a milk thistle extract of silymarin binds to estrogen receptor beta.

Likelihood Possible Evidence D
Hmg-Coa Reductase Inhibitors ("Statins")

Theoretically, milk thistle might interfere with statin therapy by decreasing the activity of organic anion transporting polypeptide 1B1 (OATB1B1) and inhibiting breast cancer resistance protein (BCRP).
Preliminary evidence suggests that a milk thistle extract of silymarin can decrease the activity of the OATP1B1, which transports HMG-CoA reductase inhibitors into the liver to their site of action, and animal research shows this increases the maximum plasma concentration of pitavastatin and pravastatin. The silibinin component also inhibits BCRP, which transports statins from the liver into the bile for excretion. However, in a preliminary study in healthy males, silymarin 140 mg three times daily had no effect on the pharmacokinetics of a single 10 mg dose of rosuvastatin.

Likelihood Unlikely Evidence D
Indinavir (Crixivan)

Theoretically, milk thistle may induce cytochrome P450 3A4 (CYP3A4) enzymes and increase the metabolism of indinavir; however, results are conflicting.
One pharmacokinetic study shows that taking milk thistle (Standardized Milk Thistle, General Nutrition Corp.) 175 mg three times daily in combination with multiple doses of indinavir 800 mg every 8 hours decreases the mean trough levels of indinavir by 25%. However, results from the same pharmacokinetic study show that milk thistle does not affect the overall exposure to indinavir. Furthermore, two other pharmacokinetic studies show that taking specific milk thistle extract (Legalon, Rottapharm Madaus; Thisilyn, Nature's Way) 160-450 mg every 8 hours in combination with multiple doses of indinavir 800 mg every 8 hours does not reduce levels of indinavir.

Likelihood Unlikely Evidence B
Organic Anion-Transporting Polypeptide Substrates (Oatp)

Milk thistle may inhibit one form of OATP, OATP-B1, which could reduce the bioavailability and clinical effects of OATP-B1 substrates.
In vitro research shows that milk thistle inhibits OATP-B1. Two case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking milk thistle and cancer medications that are OATP substrates, including sorafenib and methotrexate. OATPs are expressed in the small intestine and liver and are responsible for the uptake of drugs and other compounds into the body. Inhibition of OATP may reduce the bioavailability of oral drugs that are substrates of OATP.

Likelihood Possible Evidence D
P-Glycoprotein Substrates

Theoretically, milk thistle might increase the absorption of P-glycoprotein substrates. However, this effect does not seem to be clinically significant.
In vitro research shows that milk thistle can inhibit P-glycoprotein activity and 1 case report from the World Health Organization (WHO) adverse drug reaction database describes increased abdominal pain in a patient taking milk thistle and the cancer medication vincristine, a P-glycoprotein substrate, though this patient was also taking methotrexate. However, a small pharmacokinetic study in healthy volunteers shows that taking milk thistle (Enzymatic Therapy Inc.) 900 mg, standardized to 80% silymarin, in 3 divided doses daily for 14 days does not affect absorption of digoxin, a P-glycoprotein substrate.

Likelihood Unlikely Evidence B
Monograph

Milk Thistle: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

Milk thistle is a popular herbal supplement most often used for liver health, and its main active component is a group of compounds called silymarin. While it is generally well tolerated, the scientific evidence that it meaningfully improves liver disease or other conditions is mixed and far from conclusive. Talk with your pharmacist or doctor before using it, especially if you have a liver condition or take other medicines.

Milk Thistle
Scientific name
Silybum marianum
Family
Asteraceae
Part used
Seeds (fruit)
Common forms
Capsules, tablets, softgels, liquid extracts, tinctures, tea
People commonly use it for
  • Liver health and protection
  • Hepatitis
  • Cirrhosis
  • Gallbladder problems
  • High cholesterol
  • Type 2 diabetes support

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallUse caution

Generally well tolerated in most adults, but quality and effectiveness vary and a doctor should be involved for liver conditions.

PregnancyInsufficient reliable information

While research in an animal model shows that taking milk thistle during pregnancy and lactation does not adversely impact infant development, there is...

Read the full pregnancy detail
BreastfeedingInsufficient reliable information

While research in an animal model shows that taking milk thistle during pregnancy and lactation does not adversely impact infant development, there is...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Milk thistle (Silybum marianum) is a flowering plant in the aster family (Asteraceae). It is native to the Mediterranean region but now grows in many parts of the world. The plant gets its name from the milky-white veins on its leaves and the milky sap it produces.

Milk thistle has been used in traditional medicine for hundreds of years, mainly for problems affecting the liver and gallbladder. Today it is one of the most popular herbal supplements in the world. The seeds (fruit) are the part used to make supplements.

The active compounds are a group of plant chemicals called silymarin. Many supplements are standardized to contain a set percentage of silymarin, often around 70% to 80% in extracts.

How it works

The main active part of milk thistle is silymarin, a mix of plant compounds called flavonolignans. The most studied of these is silibinin (also called silybin).

In laboratory and animal studies, silymarin appears to act as an antioxidant, meaning it may help protect cells from a type of damage caused by unstable molecules. Researchers have also suggested it may reduce inflammation, help stabilize liver cell membranes, and support the liver's ability to repair itself.

It is important to know that much of this information comes from test-tube and animal research. How well these effects carry over to people, and at what doses, is still not fully understood.

Effectiveness

Does Milk Thistle work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by .

Evidence overview · 47 uses evaluated
1 Possibly effective 46 Insufficient evidence
How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.
2Likely EffectiveGood evidence, though not yet conclusive.
3Possibly EffectiveSome evidence suggests a benefit.
4Possibly IneffectiveSome evidence it may not help.
5Likely IneffectiveFairly strong evidence it doesn’t help.
6IneffectiveStrong evidence it doesn’t work.
7Insufficient Reliable Evidence to RateToo little research to say either way.
Possibly Effective Diabetes
Rating & evidence shown verbatim from Natural Medicines

Oral milk thistle extracts of silymarin seem to improve glycemic control in patients with diabetes.

Also studied for 46 conditions — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Acne
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral or topical milk thistle is beneficial in patients with acne when used alone or in combination with other treatments.

Insufficient Reliable Evidence To Rate Acute kidney injury (AKI)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle extract reduces the incidence of vancomycin-induced acute kidney injury.

Insufficient Reliable Evidence To Rate Alcohol-related liver disease
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in patients with alcohol-related liver disease, as evidence is conflicting.

Insufficient Reliable Evidence To Rate Allergic rhinitis (hay fever)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in patients with allergic rhinitis.

Insufficient Reliable Evidence To Rate Alzheimer disease
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in patients with Alzheimer disease.

Insufficient Reliable Evidence To Rate Amanita mushroom poisoning
Rating & evidence shown verbatim from Natural Medicines

While an intravenous milk thistle constituent, silibinin, has been studied for treating Amanita mushroom poisoning, this product is not readily available in the U.S.

Insufficient Reliable Evidence To Rate Atrial fibrillation
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for preventing atrial fibrillation after coronary artery bypass grafting.

Insufficient Reliable Evidence To Rate Benign prostatic hyperplasia (BPH)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for benign prostatic hyperplasia.

Insufficient Reliable Evidence To Rate Beta-thalassemia
Rating & evidence shown verbatim from Natural Medicines

Meta-analyses of clinical studies in patients with beta-thalassemia suggest that oral silymarin, a constituent of milk thistle, reduces serum ferritin levels.

Insufficient Reliable Evidence To Rate Chemotherapy-induced acral erythema
Rating & evidence shown verbatim from Natural Medicines

It is unclear if topical milk thistle is beneficial in patients with acral erythema due to capecitabine.

Insufficient Reliable Evidence To Rate Chemotherapy-induced hepatotoxicity
Rating & evidence shown verbatim from Natural Medicines

Results of clinical studies are mixed over whether oral milk thistle prevents or improves chemotherapy-induced hepatotoxicity.

Insufficient Reliable Evidence To Rate Chemotherapy-induced nephrotoxicity
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for the prevention of cisplatin-induced nephrotoxicity.

Insufficient Reliable Evidence To Rate Chemotherapy-induced peripheral neuropathy
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for chemotherapy-induced peripheral neuropathy.

Insufficient Reliable Evidence To Rate Contrast induced nephropathy
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for reducing the risk of nephropathy from contrast agents.

Insufficient Reliable Evidence To Rate Coronavirus disease 2019 (COVID-19)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for COVID-19.

Insufficient Reliable Evidence To Rate Critical illness (trauma)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in critically ill patients with trauma-induced liver injury.

Insufficient Reliable Evidence To Rate Diabetic nephropathy
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for improving kidney function in patients with this condition.

Insufficient Reliable Evidence To Rate Dyslipidemia
Rating & evidence shown verbatim from Natural Medicines

Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Dyspepsia
Rating & evidence shown verbatim from Natural Medicines

Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Endometriosis
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in patients with endometriosis.

Insufficient Reliable Evidence To Rate Gambling disorder
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for gambling disorder.

Insufficient Reliable Evidence To Rate Hepatitis B
Rating & evidence shown verbatim from Natural Medicines

Small clinical studies suggest that oral milk thistle extracts may improve liver function in people with hepatitis B, although it is unclear if these products can improve disease-related complications.

Insufficient Reliable Evidence To Rate Hepatitis C
Rating & evidence shown verbatim from Natural Medicines

Small clinical studies suggest that oral milk thistle extracts may improve liver function but do not seem to reduce hepatitis C virus (HCV) RNA levels.

Insufficient Reliable Evidence To Rate Hyperlipoproteinemia
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in patients with hyperlipoproteinemia secondary to liver disease.

Insufficient Reliable Evidence To Rate Hypoxic liver injury
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for reducing liver injury in patients with hypoxia.

Insufficient Reliable Evidence To Rate Infertility
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for patients undergoing in vitro fertilization.

Insufficient Reliable Evidence To Rate Lactation
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for increasing milk production.

Insufficient Reliable Evidence To Rate Melasma
Rating & evidence shown verbatim from Natural Medicines

It is unclear if topical milk thistle is beneficial in patients with melasma.

Insufficient Reliable Evidence To Rate Menopausal symptoms
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle reduces menopausal symptoms such as hot flashes.

Insufficient Reliable Evidence To Rate Metabolic dysfunction-associated steatotic liver disease (MASLD)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for MASLD.

Insufficient Reliable Evidence To Rate Metabolic syndrome
Rating & evidence shown verbatim from Natural Medicines

Oral silymarin, a constituent of milk thistle, seems to improve some of the laboratory abnormalities associated with metabolic syndrome.

Insufficient Reliable Evidence To Rate Multiple sclerosis (MS)
Rating & evidence shown verbatim from Natural Medicines

Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Nonalcoholic fatty liver disease (NAFLD)
Rating & evidence shown verbatim from Natural Medicines

Small clinical studies suggest that oral milk thistle extracts of silymarin may slightly improve markers of liver function patients with NAFLD.

Insufficient Reliable Evidence To Rate Nonalcoholic steatohepatitis (NASH)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in patients with NASH.

Insufficient Reliable Evidence To Rate Obesity
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in patients with obesity.

Insufficient Reliable Evidence To Rate Obsessive-compulsive disorder (OCD)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in patients with OCD.

Insufficient Reliable Evidence To Rate Parkinson disease
Rating & evidence shown verbatim from Natural Medicines

Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Postpartum complications
Rating & evidence shown verbatim from Natural Medicines

It is unclear if topical milk thistle is beneficial in postpartum patients with an episiotomy.

Insufficient Reliable Evidence To Rate Prostate cancer
Rating & evidence shown verbatim from Natural Medicines

Oral milk thistle has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Radiation dermatitis
Rating & evidence shown verbatim from Natural Medicines

It is unclear if topical milk thistle is beneficial in patients with dermatitis due to radiation.

Insufficient Reliable Evidence To Rate Radiation mucositis
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for preventing or treating mucositis due to radiation.

Insufficient Reliable Evidence To Rate Rheumatoid arthritis (RA)
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial for rheumatoid arthritis.

Insufficient Reliable Evidence To Rate Toxin-induced liver damage
Rating & evidence shown verbatim from Natural Medicines

Most small clinical studies suggest that oral milk thistle extracts or constituents may reduce liver injury in people exposed to some, but not all, toxins and medications known to cause liver damage.

Insufficient Reliable Evidence To Rate Trichotillomania
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in patients with this condition.

Insufficient Reliable Evidence To Rate Ulcerative colitis
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle is beneficial in patients with this condition.

Insufficient Reliable Evidence To Rate Vitiligo
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral milk thistle reduces the severity of this condition.

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

Milk thistle is generally considered well tolerated by most healthy adults when taken by mouth for short periods. Still, supplement quality can vary, and the amount of silymarin in products is not always consistent.

People who are allergic to plants in the aster/daisy family—such as ragweed, chrysanthemums, marigolds, and daisies—may be more likely to have an allergic reaction to milk thistle.

If you have a liver condition, a hormone-sensitive condition, diabetes, or any chronic illness, talk with your doctor or pharmacist before using milk thistle. Pregnancy: there is not enough reliable information, so it is best to avoid it. Breastfeeding: safety has not been well studied, so use caution and check with your healthcare provider first.

Side effects

When side effects happen, they are usually mild. The most common ones affect the stomach and gut, such as nausea, diarrhea, bloating, gas, or an upset stomach. Some people may notice a mild laxative effect.

Less commonly, people may have allergic reactions, especially if they are sensitive to ragweed or related plants. Signs can include rash, itching, or hives. Serious allergic reactions are rare but possible.

If you develop a rash, trouble breathing, swelling, or any reaction that worries you, stop taking it and seek medical care.

Milk Thistle: Reported Adverse Effects

Documented safety reports on Milk Thistle from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Orally, milk thistle is well tolerated.

Most Common Adverse Effects:

Orally: Abdominal bloating, diarrhea, dyspepsia, flatulence, and nausea. However, these adverse effects do not typically occur at a greater frequency than with placebo.

Serious Adverse Effects (Rare):

Orally: Allergic reactions, including anaphylaxis, have been reported.

Reports by condition
Cluster headache Neurologic/CNS

With oral milk thistle use, CNS symptoms have been reported, including headache, dizziness, and sleep disturbances.

  1. Rustamzadeh A, Sadigh N, Vahabi Z, et al. Effects silymarin and rosuvastatin on amyloid-carriers level in dyslipidemic Alzheimer's patients: A double-blind placebo-controlled randomized clinical trial. IBRO Neurosci Rep 2024;17:108-121.
  2. Fatemi Shandiz A, Karimi G, Dayyani M, Hosseini S, Elyasi S. Evaluation of oral silymarin formulation efficacy in prevention of doxorubicin induced hepatotoxicity in patients with non-metastatic breast cancer. J Oncol Pharm Pract 2024.
Constipation Gastrointestinal

Mild gastrointestinal symptoms have been reported, including nausea, vomiting, bloating, diarrhea, epigastric pain, abdominal colic or discomfort, dyspepsia, dysgeusia, flatulence, constipation, and loss of appetite. There is one report of a 57-year-old female with sweating, nausea, colicky abdominal pain, diarrhea, vomiting, weakness, and collapse after ingesting milk thistle; symptoms subsided after 24-48 hours without medical treatment and recurred with re-challenge.

  1. Ferenci P, Dragosics B, Dittrich H, et al. Randomized controlled trial of silymarin treatment in patients with cirrhosis of the liver. J Hepatol 1989;9:105-13.
  2. Anon. Milk thistle: Effects on liver disease and cirrhosis and clinical adverse effects. Summary, Evidence Report/Technology Assessment: Number 21, September 2000. Agency for Healthcare Research and Quality, Rockville, MD. Available at: http://www.ahrq.g
  3. Boerth J, Strong KM. The clinical utility of milk thistle (Silybum marianum) in cirrhosis of the liver. J Herb Pharmacother 2002;2:11-7.
  4. Tanamly MD, Tadros F, Labeeb S, et al. Randomised double-blinded trial evaluating silymarin for chronic hepatitis C in an Egyptian village: study description and 12-month results. Dig Liver Dis 2004;36:752-9.
  5. Allain, H., Schuck, S., Lebreton, S., Strenge-Hesse, A., Braun, W., Gandon, J. M., and Brissot, P. Aminotransferase levels and silymarin in de novo tacrine-treated patients with Alzheimer's disease. Dement.Geriatr.Cogn Disord. 1999;10(3):181-185.
  6. Angulo, P., Patel, T., Jorgensen, R. A., Therneau, T. M., and Lindor, K. D. Silymarin in the treatment of patients with primary biliary cirrhosis with a suboptimal response to ursodeoxycholic acid. Hepatology 2000;32(5):897-900.
  7. Bean, P. The use of alternative medicine in the treatment of hepatitis C. Am.Clin.Lab 2002;21(4):19-21.
  8. El-Kamary, S. S., Shardell, M. D., Abdel-Hamid, M., Ismail, S., El-Ateek, M., Metwally, M., Mikhail, N., Hashem, M., Mousa, A., Aboul-Fotouh, A., El-Kassas, M., Esmat, G., and Strickland, G. T. A randomized controlled trial to assess the safety and effic
  9. Ladas, E. J., Kroll, D. J., Oberlies, N. H., Cheng, B., Ndao, D. H., Rheingold, S. R., and Kelly, K. M. A randomized, controlled, double-blind, pilot study of milk thistle for the treatment of hepatotoxicity in childhood acute lymphoblastic leukemia (ALL
  10. Sayyah, M., Boostani, H., Pakseresht, S., and Malayeri, A. Comparison of Silybum marianum (L.) Gaertn. with fluoxetine in the treatment of Obsessive-Compulsive Disorder. Prog.Neuropsychopharmacol.Biol.Psychiatry 3-17-2010;34(2):362-365.
  11. Flaig, T. W., Glode, M., Gustafson, D., van, Bokhoven A., Tao, Y., Wilson, S., Su, L. J., Li, Y., Harrison, G., Agarwal, R., Crawford, E. D., Lucia, M. S., and Pollak, M. A study of high-dose oral silybin-phytosome followed by prostatectomy in patients w
  12. Loguercio C, Andreone P, Brisc C, et al. Silybin combined with phosphatidylcholine and vitamin E in patients with nonalcoholic fatty liver disease: a randomized controlled trial. Free Radic Biol Med 2012;52(9):1658-65.
  13. Yakoot, M. and Salem, A. Spirulina platensis versus silymarin in the treatment of chronic hepatitis C virus infection. A pilot randomized, comparative clinical trial. BMC.Gastroenterol. 2012;12:32.
  14. Fallahzadeh, M. K., Dormanesh, B., Sagheb, M. M., Roozbeh, J., Vessal, G., Pakfetrat, M., Daneshbod, Y., Kamali-Sarvestani, E., and Lankarani, K. B. Effect of addition of silymarin to renin-angiotensin system inhibitors on proteinuria in type 2 diabetic
  15. Fried, M. W., Navarro, V. J., Afdhal, N., Belle, S. H., Wahed, A. S., Hawke, R. L., Doo, E., Meyers, C. M., and Reddy, K. R. Effect of silymarin (milk thistle) on liver disease in patients with chronic hepatitis C unsuccessfully treated with interferon t
  16. Marcelli R, Bizzoni P, Conte D, and et al. Randomized controlled study of the efficacy and tolerability of a short course of IdB 1016 in the treatment of chronic persistent hepatitis. Eur Bull Drug Res 1992;1(3):131-135.
  17. Vailati A, Aristia L, Sozze E, and et al. Randomized open study of the dose-effect relationship of a short course of IdB 1016 in patients with viral or alcoholic hepatitis. Fitoterapia 1993;64(3):219-228.
  18. Marena C and Lampertico M. Preliminary clinical development of silipide: a new complex of silybin in toxic liver disorders. Planta Med 1991;57(2):A124-A125.
  19. Grungreiff K, Albrecht M, and Strenge-Hesse A. Benefit of medicinal liver therapy in general practice. Med Welt 1995;46:222-227.
  20. Frerick F, Kuhn U, and Strenge-Hesse A. Silymarin--ein Phytopharmakon zur Behandlung toxischen Leberschaden: Anwendungsbeobachtung bei 2169 Patienten. Kassenarzt 1990;33:36-41.
  21. Schuppan D, Strosser W, Burkard G, and et al. Influence of Legalon(TM) 140 on the metabolism of collagen in patients with chronic liver disease--Review by measurement of PIIINP-values. Zeitschrift fur Allgemeinmedizin 1998;74:577-584.
  22. Studlar M. Die Behandlung chronischer Leberkrankungen mit Silymarin und B-Vitaminen. Therapiewoche 1985;35:3375-3378.
  23. Luangchosiri C, Thakkinstian A, Chitphuk S, Stitchantrakul W, Petraksa S, Sobhonslidsuk A. A double-blinded randomized controlled trial of silymarin for the prevention of antituberculosis drug-induced liver injury. BMC Complement Altern Med. 2015;15:334.
  24. Rastegarpanah M, Malekzadeh R, Vahedi H, et al. A randomized, double blinded, placebo-controlled clinical trial of silymarin in ulcerative colitis. Chin J Integr Med. 2015;21(12):902-6.
  25. Soleymani S, Ayati MH, Mansourzadeh MJ, Namazi N, Zargaran A. The effects of Silymarin on the features of cardiometabolic syndrome in adults: A systematic review and meta-analysis. Phytother Res. 2022 Jan 11. doi: 10.1002/ptr.7364.
  26. Fatemi Shandiz A, Karimi G, Dayyani M, Hosseini S, Elyasi S. Evaluation of oral silymarin formulation efficacy in prevention of doxorubicin induced hepatotoxicity in patients with non-metastatic breast cancer. J Oncol Pharm Pract 2024.
  27. Anon. Adverse reaction: milk thistle-associated toxicity. Nurse Drug Alert 1999;23(7):51.
Eczema Dermatologic

Orally, milk thistle may cause allergic reactions including urticaria, eczema, skin rash, and anaphylaxis in some people. Allergic reactions may be more likely to occur in patients sensitive to the Asteraceae/Compositae family. A case report describes a 49-year-old female who developed clinical, serologic, and immunopathologic features of bullous pemphigoid after taking milk thistle orally for 6 weeks. Symptoms resolved after treatment with prednisone and methotrexate. Topically, milk thistle can cause erythema.

  1. Anon. Milk thistle: Effects on liver disease and cirrhosis and clinical adverse effects. Summary, Evidence Report/Technology Assessment: Number 21, September 2000. Agency for Healthcare Research and Quality, Rockville, MD. Available at: http://www.ahrq.g
  2. Pares A, Planas R, Torres M, et al. Effects of silymarin in alcoholic patients with cirrhosis of the liver: results of a controlled, double-blind, randomized and multicenter trial. J Hepatol 1998;28:615-21.
  3. Boerth J, Strong KM. The clinical utility of milk thistle (Silybum marianum) in cirrhosis of the liver. J Herb Pharmacother 2002;2:11-7.
  4. El-Kamary, S. S., Shardell, M. D., Abdel-Hamid, M., Ismail, S., El-Ateek, M., Metwally, M., Mikhail, N., Hashem, M., Mousa, A., Aboul-Fotouh, A., El-Kassas, M., Esmat, G., and Strickland, G. T. A randomized controlled trial to assess the safety and effic
  5. Gharagozloo, M., Moayedi, B., Zakerinia, M., Hamidi, M., Karimi, M., Maracy, M., and Amirghofran, Z. Combined therapy of silymarin and desferrioxamine in patients with beta-thalassemia major: a randomized double-blind clinical trial. Fundam.Clin.Pharmaco
  6. Ramirez-Santos, A., Perez-Bustillo, A., Gonzalez-Sixto, B., Suarez-Amor, O., and Rodriguez-Prieto, M. A. [Acute generalized exanthematous pustulosis due to milk thistle (Silybum marianum) tea]. Actas Dermosifiliogr. 2011;102(9):744-745.
  7. Fried, M. W., Navarro, V. J., Afdhal, N., Belle, S. H., Wahed, A. S., Hawke, R. L., Doo, E., Meyers, C. M., and Reddy, K. R. Effect of silymarin (milk thistle) on liver disease in patients with chronic hepatitis C unsuccessfully treated with interferon t
  8. Mironets VI, Krasovskaia EA, and Polishchuk II. [A case of urticaria during Carsil treatment]. Vrach Delo 1990;7:86-87.
  9. Frerick F, Kuhn U, and Strenge-Hesse A. Silymarin--ein Phytopharmakon zur Behandlung toxischen Leberschaden: Anwendungsbeobachtung bei 2169 Patienten. Kassenarzt 1990;33:36-41.
  10. Rastegarpanah M, Malekzadeh R, Vahedi H, et al. A randomized, double blinded, placebo-controlled clinical trial of silymarin in ulcerative colitis. Chin J Integr Med. 2015;21(12):902-6.
  11. Gamissans M, Expósito-Serrano V, López-Llunell C, Valdivieso L, Garbayo-Salmons P. Bullous pemphigoid triggered by Silybum marianum: an unexpected side effect of an herbal remedy. Int J Dermatol. 2021 Aug 7. doi: 10.1111/ijd.15822.
  12. Wattanakrai P, Nimmannitya K. A Randomized, Double-Blind, Split-Face Study of Topical Silymarin vs 2% Hydroquinone Cream in Melasmas. J Drugs Dermatol 2022;21(12):1304-1310.
Myasthenia gravis Musculoskeletal

In one clinical study three patients taking milk thistle 200 mg orally three times daily experienced tremor; the incidence of this adverse effect was similar for patients treated with fluoxetine 10 mg three times daily.

  1. Sayyah, M., Boostani, H., Pakseresht, S., and Malayeri, A. Comparison of Silybum marianum (L.) Gaertn. with fluoxetine in the treatment of Obsessive-Compulsive Disorder. Prog.Neuropsychopharmacol.Biol.Psychiatry 3-17-2010;34(2):362-365.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no single official or proven dose for milk thistle. Studies have used a wide range of amounts, and products differ in how much silymarin they contain, which makes comparing doses difficult.

The best approach is to follow the directions on the product label and choose a reputable brand. Look for products that list a standardized silymarin content. Because supplements are not tightly regulated, quality can vary between brands.

Before starting milk thistle—especially if you have a health condition, take other medicines, or are pregnant or breastfeeding—check with your pharmacist or doctor to make sure it is appropriate for you.

Pregnancy & Breastfeeding

Milk Thistle & Pregnancy

Insufficient reliable information

While research in an animal model shows that taking milk thistle during pregnancy and lactation does not adversely impact infant development, there is insufficient reliable information available about its safety during pregnancy or lactation in humans; avoid using.

Milk Thistle & Breastfeeding

Insufficient reliable information

While research in an animal model shows that taking milk thistle during pregnancy and lactation does not adversely impact infant development, there is insufficient reliable information available about its safety during pregnancy or lactation in humans; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 69 references that drive our Milk Thistle monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Ferenci P, Dragosics B, Dittrich H, et al. Randomized controlled trial of silymarin treatment in patients with cirrhosis of the liver. J Hepatol 1989;9:105-13. PubMed
  2. Anon. Milk thistle: Effects on liver disease and cirrhosis and clinical adverse effects. Summary, Evidence Report/Technology Assessment: Number 21, September 2000. Agency for Healthcare Research and Quality, Rockville, MD. Available at: http://www.ahrq.g
  3. Beckmann-Knopp S, Rietbrock S, Weyhenmeyer R, et al. Inhibitory effects of silibinin on cytochrome P-450 enzymes in human liver microsomes. Pharmacol Toxicol 2000;86:250-6. PubMed
  4. Venkataramanan R, Ramachandran V, Komoroski BJ, et al. Milk thistle, a herbal supplement, decreases the activity of CYP3A4 and uridine diphosphoglucuronosyl transferase in human hepatocyte cultures. Drug Metab Dispos 2000;28:1270-3. DOI
  5. Kim DH, Jin YH, Park JB, Kobashi K. Silymarin and its components are inhibitors of beta-glucuronidase. Biol Pharm Bull 1994;17:443-5. PubMed
  6. Pares A, Planas R, Torres M, et al. Effects of silymarin in alcoholic patients with cirrhosis of the liver: results of a controlled, double-blind, randomized and multicenter trial. J Hepatol 1998;28:615-21. PubMed
  7. Piscitelli SC, Formentini E, Burstein AH, et al. Effect of milk thistle on the pharmacokinetics of indinavir in healthy volunteers. Pharmacotherapy 2002;22:551-6. PubMed
  8. Boerth J, Strong KM. The clinical utility of milk thistle (Silybum marianum) in cirrhosis of the liver. J Herb Pharmacother 2002;2:11-7.
  9. Tanamly MD, Tadros F, Labeeb S, et al. Randomised double-blinded trial evaluating silymarin for chronic hepatitis C in an Egyptian village: study description and 12-month results. Dig Liver Dis 2004;36:752-9. PubMed
  10. Gurley BJ, Gardner SF, Hubbard MA, et al. In vivo assessment of botanical supplementation on human cytochrome P450 phenotypes: Citrus aurantium, Echinacea purpurea, milk thistle, and saw palmetto. Clin Pharmacol Ther 2004;76:428-40. .
  11. Huseini HF, Larijani B, Heshmat R, et al. The efficacy of Silybum marianum (L.) Gaertn. (silymarin) in the treatment of type II diabetes: a randomized, double-blind, placebo-controlled, clinical trial. Phytother Res 2006;20;1036-9.
  12. Deng JW, Shon JH, Shin HJ, et al. Effect of silymarin supplement on the pharmacokinetics of rosuvastatin. Pharm Res 2008;25:1807-14. PubMed
  13. Kim CS, Choi SJ, Park CY, et al. Effects of silybinin on the pharmacokinetics of tamoxifen and its active metabolite, 4-hydroxytamoxifen in rats. Anticancer Res 2010;30:79-85.
  14. Sridar C, Goosen TC, Kent UM, et al. Silybin inactivates cytochromes P450 3A4 and 2C9 and inhibits major hepatic glucuronosyltransferases. Drug Metab Dispos 2004;32:587-94. PubMed
  15. van Erp NP, Baker SD, Zhao M, et al. Effect of milk thistle (Silybum marianum) on the pharmacokinetics of irinotecan. Clin Cancer Res 2005;11:7800-6.
Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Brand directory

Brands that make products with Milk Thistle

883 brands in our database make a supplement containing Milk Thistle.

Product directory

Supplement products with Milk Thistle

4,579 products in our database contain Milk Thistle. Open any to see its full ingredient list and every drug interaction we check.

3-Day Cleanse Morning Formula by Renew Life Capsule 6 Vegetarian Capsule(s) View ingredients & interactions 3-Day Liver Cleanse Evening Formula by Renew Life Capsule 6 Vegetarian Capsule(s) View ingredients & interactions 3-Day Liver Cleanse Morning Formula by Renew Life Capsule 6 Vegetarian Capsule(s) View ingredients & interactions 37 Strawberries by Purity Products Capsule 30 Capsule(s) View ingredients & interactions A.Vogel Liver Gallbladder Drops by Bioforce Liquid 1.7 fl. Oz. · 50 mL View ingredients & interactions A.Vogel Liver Gallbladder Tablets by Bioforce Tablet Or Pill 60 Tablet(s) View ingredients & interactions Able Eyes by Carlson Softgel Capsule 60 Softgel(s) View ingredients & interactions Able Eyes by Carlson Softgel Capsule 180 Softgel(s) View ingredients & interactions Able Eyes by Carlson Softgel Capsule 90 Softgel(s) View ingredients & interactions Able Eyes by Carlson Softgel Capsule 30 Softgel(s) View ingredients & interactions Absolute Cleanse by New Sun Capsule 140 Vegetarian Capsule(s) View ingredients & interactions AcaiCleanse Natural 10 Day Acai Berry Detox by Garden Greens Tablet Or Pill 120 Tablet(s) View ingredients & interactions Accutrophin by Physician's Signature Capsule 60 Capsule(s) View ingredients & interactions Activate by Modere Powder 0.9 oz · 27 Gram(s) View ingredients & interactions Active by Complete Active Capsule 90 Capsule(s) View ingredients & interactions Active Liver by New Nordic Tablet Or Pill 30 Tablet(s) View ingredients & interactions Active Liver Vegan Gummies by New Nordic Gummy Or Jelly 60 Gummy(ies) View ingredients & interactions Active Mixed Berry by GNC Ultra Mega Green Powder 34.7 oz. · 2.17 lb · 984 Gram(s) View ingredients & interactions Active Multi by FINAFLEX Capsule 120 Capsule(s) View ingredients & interactions Active Multi by FINAFLEX Capsule 240 Capsule(s) View ingredients & interactions ActivNutrients Performance by XYMOGEN Capsule 120 Vegetarian Capsule(s) View ingredients & interactions ActivNutrients Phyto by XYMOGEN Capsule 90 Vegetarian Capsule(s) View ingredients & interactions ActivNutrients Phyto by XYMOGEN Capsule 90 Vegetarian Capsule(s) View ingredients & interactions Adrenal Power by New Sun Liquid 2 fl. Oz. · 59 mL View ingredients & interactions
Pharmacist Counseling Corner

Milk Thistle: Common Questions

What is Milk Thistle used for, and does it work?
People use Milk Thistle for many reasons, but the evidence varies by use. According to the Natural Medicines database, there is at least some clinical evidence supporting Milk Thistle for Diabetes. For most other uses it has been studied for, the evidence is currently insufficient to rate. See the graded list on this page, and always confirm with your pharmacist or doctor.
Does Milk Thistle interact with prescription medications?
Yes. We list 954 medications with a known interaction with Milk Thistle. Use the checker above to see how Milk Thistle interacts with a specific drug.
How are Milk Thistle interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Milk Thistle with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Milk Thistle interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
What is Milk Thistle mainly used for?
It is most often used for liver health, including conditions like hepatitis and cirrhosis, as well as for gallbladder issues and high cholesterol. However, the evidence that it works for these uses is mixed and not conclusive.
Is Milk Thistle safe to take?
It is generally well tolerated by most healthy adults, with mild stomach upset being the most common side effect. People allergic to ragweed or related plants should be cautious, and anyone with a health condition should check with a pharmacist or doctor first.
Can I take Milk Thistle during pregnancy or while breastfeeding?
There is not enough reliable safety information, so it is best to avoid Milk Thistle during pregnancy and to use caution while breastfeeding. Talk with your healthcare provider before using it.
Does Milk Thistle actually protect the liver?
It is popular for liver support, but high-quality human studies have given mixed results, and there is not strong proof that it treats liver disease. It should never replace proper medical care for a liver condition.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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