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Milk Thistle (Silymarin)
Bottom line
In our scoring, Milk Thistle (Silymarin) rates mixed evidence: the evidence is mixed for liver enzymes (ALT/AST) in NAFLD/NASH. Our top-scored product is Jarrow Formulas Milk Thistle 150mg (85/100), about $0.11 a day at a clinical dose of 420-600mg silymarin per day, divided into 2-3 doses. Bottom line: promising but not settled, so manage expectations. This is our opinion, not medical advice; talk to your clinician before starting.
For a healthy liver, milk thistle does nothing the evidence can point to - the "detox" and "protect" pitch is not backed up, so save your money.
- Evidence
- Mixed Evidence
- Category
- Herbal & Botanical
- Best form
- silymarin standardized to 70-80%
- Effective dose
- 420-600mg silymarin per day, divided into 2-3 doses (standardized to 70-80% silymarin)
- Lab tested
- 7 of 10 products
- Category
- Herbal & Botanical
- Best form
- silymarin standardized to 70-80%
- Effective dose
- 420-600mg silymarin per day, divided into 2-3 doses (standardized to 70-80% silymarin)
- Lab tested
- 7 of 10 products
Key takeaways
- →Evidence is mixed: modest ALT/AST reduction in NAFLD trials, null for hepatitis C, and zero evidence for 'detoxing' a healthy liver.
- →Clinical dose is 420-600mg silymarin (standardized 70-80%) split into 2-3 doses; phytosome forms (Siliphos) absorb 3-5x better.
- →Nutricost ($0.12/day for a 500mg silymarin dose) is the value pick; Thorne's Milk Thistle Phytosome is the bioavailability pick, though its 2026 repricing pushed it to about $1.07/day.
- →Avoid if pregnant, breastfeeding, or allergic to ragweed; can interact with warfarin, statins, and diabetes meds via CYP enzymes.
What Is Milk Thistle (Silymarin)?
For a healthy liver, milk thistle does nothing the evidence can point to - the "detox" and "protect" pitch is not backed up, so save your money. The marketing leans on the word "detox," but your liver is already your body's detox organ, and a supplement does not give it a boost it was missing. The one population with a reasonable case is fatty liver disease, where a review of 8 trials found a modest drop in liver enzymes; even there, a broader Cochrane review graded the evidence low-certainty and saw no effect on deaths or complications. The reputation here runs well ahead of what the trials actually show.
It helps to know what is in the bottle. Milk thistle is the plant (Silybum marianum); the active part is silymarin, a group of plant compounds (flavonolignans) pulled from its seeds. The most active piece of that mix is silybin (also spelled silibinin), which makes up roughly 50-70% of silymarin. In the lab, in cells and animals, silymarin behaves like an antioxidant and anti-inflammatory and looks protective to liver tissue. The open question is whether any of that shows up as a real benefit in actual people - and mostly, it has not.
Take hepatitis C. The cleanest test we have is a well-designed NIH trial (the SyNCH study) that gave silymarin to people with chronic hepatitis C at two different doses. The answer came back flat: compared to placebo, silymarin did not lower liver enzymes (a blood marker of liver stress) or reduce viral load at either dose.
Fatty liver disease is the one place there is a reasonable case. Pooling 8 trials, silymarin modestly but consistently nudged liver enzymes down in people with fatty liver. The caveat matters, though: a broader Cochrane review (the kind that grades how trustworthy the underlying studies are) called this evidence low-certainty, and silymarin did not reduce deaths or liver complications in any trial.
For alcoholic liver disease the pattern repeats - silymarin may pull elevated liver enzymes down, but the best-designed trials found no effect on survival or other outcomes that actually matter.
So here is the honest read. If a doctor has flagged elevated liver enzymes from fatty liver disease, silymarin at 420mg a day or more might bring those numbers down a little, alongside the real work of diet and weight. If your liver is healthy and you are taking this to undo a weekend of drinking, the evidence simply is not there.
One more thing worth knowing before you buy. Silymarin is poorly absorbed - a lot of a standard extract passes through you without ever reaching your bloodstream. Phytosome formulations (silybin bound to phosphatidylcholine, sold as Siliphos and similar) get 3-5x more silybin into the blood in absorption studies. If you have a documented liver condition and are taking this on purpose, the phytosome form is the more sensible pick.
Does It Work? The Evidence
How A-F grades workMilk Thistle (Silymarin) earns a Mixed Evidence rating: the research is suggestive but not settled. Its best-supported use so far is reducing liver enzymes (ALT/AST) in NAFLD/NASH (grade B), but the evidence across claims is mixed - each is graded on its own below.
Reducing liver enzymes (ALT/AST) in NAFLD/NASH
Zhong et al. 2017 meta-analysis of 8 RCTs; Salomone et al. 2016 systematic review; multiple small RCTs showing ALT/AST reduction
Hepatitis C treatment (ALT reduction, viral load)
SyNCH trial (Fried et al. JAMA 2012, n=154) - negative for ALT and HCV RNA at both 420mg and 700mg TID; PMID 23150005
Alcoholic liver disease (mortality, complications)
Rambaldi et al. 2007 Cochrane review of 18 RCTs; 2020 Cochrane update - no significant effect on mortality or liver complications
Blood sugar reduction in type 2 diabetes
Voroneanu et al. 2016 meta-analysis showed modest fasting glucose reduction; small trials with methodological limitations
Chemotherapy-induced liver toxicity (adjunctive use)
Small RCTs in pediatric ALL patients (Ladas et al. 2010); some signal for hepatoprotection during chemotherapy but insufficient data
Liver protection in healthy individuals ('detox')
No RCTs in healthy populations; no evidence that healthy livers need supplemental 'support' or 'detoxification'
| Grade | Claimed Benefit | Key Studies | Our Verdict |
|---|---|---|---|
| B | Reducing liver enzymes (ALT/AST) in NAFLD/NASH | Zhong et al. 2017 meta-analysis of 8 RCTs; Salomone et al. 2016 systematic review; multiple small RCTs showing ALT/AST reduction | Early Signal |
| C | Hepatitis C treatment (ALT reduction, viral load) | SyNCH trial (Fried et al. JAMA 2012, n=154) - negative for ALT and HCV RNA at both 420mg and 700mg TID; PMID 23150005 | Ineffective |
| C | Alcoholic liver disease (mortality, complications) | Rambaldi et al. 2007 Cochrane review of 18 RCTs; 2020 Cochrane update - no significant effect on mortality or liver complications | Not There Yet |
| C | Blood sugar reduction in type 2 diabetes | Voroneanu et al. 2016 meta-analysis showed modest fasting glucose reduction; small trials with methodological limitations | Early Signal |
| C | Chemotherapy-induced liver toxicity (adjunctive use) | Small RCTs in pediatric ALL patients (Ladas et al. 2010); some signal for hepatoprotection during chemotherapy but insufficient data | Early Signal |
| F | Liver protection in healthy individuals ('detox') | No RCTs in healthy populations; no evidence that healthy livers need supplemental 'support' or 'detoxification' | Ineffective |
Milk Thistle (Silymarin) Dosage: How Much to Take
Milk Thistle (Silymarin) dosage, in one line: the evidence-supported range is 420-600mg silymarin per day, divided into 2-3 doses (standardized to 70-80% silymarin).
Clinical dose: 420-600mg silymarin per day, divided into 2-3 doses (standardized to 70-80% silymarin)
Best forms: silymarin standardized to 70-80%, silybin phytosome (Siliphos) for improved bioavailability
Aim for 420-600mg of silymarin a day, split into 2-3 doses with meals. The number that matters is the silymarin content, not the headline weight on the front of the bottle. Most standardized extracts are 70-80% silymarin, so a typical 175mg silymarin capsule means 2-3 capsules a day to land in the clinical range. If you go with a phytosome form (Siliphos), you can take less - usually 160-480mg of silybin phytosome a day - because more of it actually gets absorbed. Taking it with food may sit easier on your stomach, though absorption stays modest either way. Trials ran for about 3-6 months, so this is not a take-it-for-a-few-days thing. If you started it for elevated liver enzymes, recheck your labs after 8-12 weeks to see whether the numbers actually moved.
Who Should Take Milk Thistle (Silymarin)?
This is for a narrow group, not the general public. If a doctor has diagnosed you with non-alcoholic fatty liver disease (NAFLD/NASH) and your liver enzymes are elevated, milk thistle is reasonable to try as add-on support while you do the heavier lifting (diet, exercise, weight loss). The same goes if you have alcoholic liver disease and are working with a doctor - it is well tolerated, so trying it alongside medical care carries little downside. Those are the populations the evidence actually speaks to. If your liver enzymes are normal and you have no diagnosed liver condition, you are unlikely to feel or measure anything from it.
Who Should Avoid It?
Not for everyone
Side Effects & Safety
Product Scores
10 products scored on dosing accuracy, third-party testing, cost per effective dose, and label transparency.
The Scorecard: 10 Products Compared
Jarrow Formulas Milk Thistle 150mg
Jarrow Formulas$22.99 ÷ 209 days at 150mg silymarin (80% flavonoids)/day (1 serving × 150mg silymarin (80% flavonoids))
The standard silymarin extract from a reliable brand at an excellent price. For most people with general liver support goals, this form and dose is supported by the clinical evidence base.
Prices checked 2026-06-11. Cost shown is per clinically effective daily dose, not per pill.
NOW Foods Silymarin Milk Thistle Extract 300mg
NOW Foods$25.74 ÷ 99 days at 600mg silymarin extract (80%)/day (2 servings × 300mg silymarin extract (80%))
Strong price-to-quality ratio for standard silymarin even after the 2026 price rise. NOW Foods has a strong track record for delivering what the label says. Just know you need 2 capsules daily for a clinical dose.
Prices checked 2026-06-11. Cost shown is per clinically effective daily dose, not per pill.
Life Extension Advanced Milk Thistle (Silymarin + Phosphatidylcholine)
Life Extension$32.10 ÷ 59 days at 720mg silymarin complex/day (2 servings × 360mg silymarin complex)
Hybrid approach combining standard silymarin with phosphatidylcholine-complexed silybin. Reasonable formulation, but Thorne's Milk Thistle Phytosome is a cleaner, more straightforward phytosome product.
Prices checked 2026-06-11. Cost shown is per clinically effective daily dose, not per pill.
Pure Encapsulations Silymarin 250mg
Pure Encapsulations$45.00 ÷ 60 days at 500mg silymarin/day (2 servings × 250mg silymarin)
Best option for people with multiple food allergies or sensitivities. Otherwise, in our view, hard to justify the roughly 3x price premium over NOW Foods for what is essentially the same active ingredient.
Prices checked 2026-06-11. Cost shown is per clinically effective daily dose, not per pill.
Nutricost Milk Thistle 250mg (80% Silymarin)
Nutricost$13.95 ÷ 116 days at 500mg silymarin extract (80%)/day (2 servings × 250mg silymarin extract (80%))
Extremely cheap, but with supplements - especially herbal extracts - you often get what you pay for. Without independent verification, you are trusting the label at face value. Budget pick only if cost is the primary concern.
Prices checked 2026-06-11. Cost shown is per clinically effective daily dose, not per pill.
Thorne Siliphos 160mg
Thorne$48.00 ÷ 45 days at 320mg silybin phytosome/day (2 servings × 160mg silybin phytosome)
If you need NSF Certified for Sport verification (competitive athletes, military) this is the only option. Otherwise, the standard silymarin extract options offer good value if you do not need the phytosome form.
Prices checked 2026-06-11. Cost shown is per clinically effective daily dose, not per pill.
Nature Made Milk Thistle 140mg
Nature Made$9.99 ÷ 17 days at 420mg silymarin/day (3 servings × 140mg silymarin)
USP Verified is a major quality advantage, but the low per-capsule dose is a problem. You need 3 capsules daily to approach clinical dosing, making this more expensive per effective dose than it looks.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Puritan's Pride Milk Thistle 4:1 Extract 1000mg
Puritan's Pride
$14.99 ÷ 187 days at 1000mg milk thistle 4:1 extract/day (1 serving × 1000mg milk thistle 4:1 extract)
The '1000mg' on the label looks impressive but is meaningless without silymarin standardization. This is a textbook example of why reading beyond the headline number matters. Avoid.
Prices checked 2026-05-18. Cost shown is per clinically effective daily dose, not per pill.
Nature's Bounty Milk Thistle 175mg
Nature's Bounty
$9.99 ÷ 33 days at 525mg silymarin/day (3 servings × 175mg silymarin)
The 175mg dose is too low to reach clinical levels without tripling the serving size. Combined with no third-party certification, there are better options at every price point.
Prices checked 2026-06-11. Cost shown is per clinically effective daily dose, not per pill.
Spring Valley Milk Thistle 175mg
Spring Valley$7.48 ÷ 20 days at 525mg silymarin/day (3 servings × 175mg silymarin)
Bottom of the category in our scoring. No third-party testing, low dose per capsule relative to the clinical target, from a store brand with a spotty quality history. The low shelf price is, in our view, misleading on value - reaching an effective dose costs more than with better-tested alternatives.
Prices checked 2026-04-01. Cost shown is per clinically effective daily dose, not per pill.
Full Comparison
| Category | Jarrow Formulas Milk Thistle 150mg Jarrow Formulas | NOW Foods Silymarin Milk Thistle Extract 300mg NOW Foods | Life Extension Advanced Milk Thistle (Silymarin + Phosphatidylcholine) Life Extension | Pure Encapsulations Silymarin 250mg Pure Encapsulations | Nutricost Milk Thistle 250mg (80% Silymarin) Nutricost | Thorne Siliphos 160mg Thorne | Nature Made Milk Thistle 140mg Nature Made | Puritan's Pride Milk Thistle 4:1 Extract 1000mg Puritan's Pride | Nature's Bounty Milk Thistle 175mg Nature's Bounty | Spring Valley Milk Thistle 175mg Spring Valley |
|---|---|---|---|---|---|---|---|---|---|---|
| Brand Score | 85/100Winner | 77/100 | 77/100 | 77/100 | 76/100 | 75/100 | 74/100 | 64/100 | 59/100 | 47/100 |
| Dosing & Form | 18/25 | 18/25 | 22/25 | 18/25 | 18/25 | 14/25 | 14/25 | 25/25Winner | 14/25 | 14/25 |
| Purity | 22/25 | 20/25 | 20/25 | 23/25 | 15/25 | 25/25Winner | 23/25 | 13/25 | 17/25 | 9/25 |
| Value | 22/25 | 19/25 | 15/25 | 11/25 | 24/25Winner | 11/25 | 17/25 | 17/25 | 13/25 | 13/25 |
| Transparency | 23/25 | 20/25 | 20/25 | 25/25Winner | 19/25 | 25/25 | 20/25 | 9/25 | 15/25 | 11/25 |
| Cost/Day | $0.11 | $0.26 | $0.54 | $0.75 | $0.12 | $1.07 | $0.60 | $0.08Winner | $0.30 | $0.37 |
| Dose/Serving | 150mg silymarin (80% flavonoids) | 300mg silymarin extract (80%) | 360mg silymarin complex | 250mg silymarin | 250mg silymarin extract (80%) | 160mg silybin phytosome | 140mg silymarin | 1000mg milk thistle 4:1 extract | 175mg silymarin | 175mg silymarin |
| Form | standardized silymarin extract capsule (30:1) | standardized silymarin extract (80%) veggie capsule | silybin-phosphatidylcholine complex + silymarin extract softgel | standardized silymarin extract capsule | standardized silymarin extract (80%) capsule | silybin phytosome (Siliphos) capsule | standardized silymarin extract softgel | milk thistle 4:1 extract softgel (silymarin % not specified) | standardized silymarin extract softgel | standardized silymarin extract capsule |
| Third-Party Tested | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | ✓ Yes | No | No | No |
| Proprietary Blend | No | No | No | No | No | No | No | No | No | No |
Frequently Asked Questions
Does milk thistle actually detox the liver?
No. The concept of 'liver detox' through supplements is not supported by evidence. Your liver is already your body's primary detoxification organ and does not need supplemental help in healthy individuals. Silymarin shows antioxidant and anti-inflammatory properties in lab settings, and may help reduce elevated liver enzymes in people with fatty liver disease, but this is not 'detoxification' - it is modest anti-inflammatory support in people with an existing liver condition. If your liver function tests are normal, there is no evidence milk thistle does anything useful.
What is the difference between milk thistle and silymarin?
Milk thistle (Silybum marianum) is the plant. Silymarin is the active flavonolignan complex extracted from milk thistle seeds, typically standardized to make up 70-80% of the extract. Silybin (silibinin) is the most biologically active component within silymarin, accounting for roughly 50-70% of the complex. When studies test 'milk thistle,' they are almost always using a standardized silymarin extract. Look for products that specify silymarin content, not just raw milk thistle seed powder.
Is the phytosome form of milk thistle worth the extra cost?
If you have a documented liver condition and are taking milk thistle therapeutically, yes, the phytosome form is worth considering. Pharmacokinetic studies show that silybin phytosome (complexed with phosphatidylcholine, branded as Siliphos) achieves 3-5x higher plasma silybin levels than standard silymarin extract. This means you can take a lower dose and get more silybin into your bloodstream. If you are taking milk thistle 'just in case' without a specific liver condition, the phytosome form is a more expensive way to take something you probably do not need.
Can milk thistle help with a hangover?
There is no evidence that milk thistle prevents or treats hangovers. A few very small studies have looked at silymarin for acute alcohol exposure, but there are no RCTs supporting hangover prevention or treatment. The mild anti-inflammatory properties of silymarin are not going to meaningfully counteract the dehydration, acetaldehyde toxicity, and inflammation caused by binge drinking. Save your money.
How long does it take for milk thistle to work?
In clinical trials for NAFLD, significant reductions in liver enzymes were typically seen after 8-12 weeks of daily use at 420mg+ silymarin per day. Some trials ran for 6 months. If you are taking it for elevated liver enzymes, get a baseline liver panel before starting and recheck after 2-3 months. If there is no improvement, it is probably not working for you.
Can I take milk thistle with alcohol?
There is no known dangerous interaction between milk thistle and alcohol. Some people take it hoping to 'protect' their liver from alcohol damage. While silymarin has shown modest hepatoprotective effects in alcoholic liver disease patients with existing damage, there is no evidence it prevents liver damage from ongoing alcohol consumption. Reducing alcohol intake is infinitely more effective than any supplement.
Does milk thistle interact with medications?
Silymarin can inhibit cytochrome P450 enzymes CYP2C9 and CYP3A4 in vitro, which could theoretically affect the metabolism of drugs processed by these enzymes (including warfarin, certain statins, and some anti-anxiety medications). However, clinical studies at standard doses have generally not shown significant drug interactions. Still, if you take prescription medications - especially those with narrow therapeutic windows - consult your doctor or pharmacist before adding milk thistle.
What is the right Milk Thistle (Silymarin) dosage?
The evidence-supported range is 420-600mg silymarin per day, divided into 2-3 doses (standardized to 70-80% silymarin). Aim for 420-600mg of silymarin a day, split into 2-3 doses with meals. See the dosage section above for timing and form details, and talk to your clinician about the right dose for you.
Related Articles
Sources
- Fried MW, et al. Effect of silymarin (milk thistle) on liver disease in patients with chronic hepatitis C unsuccessfully treated with interferon therapy: a randomized controlled trial (SyNCH). JAMA. 2012;308(3):274-282.
- Zhong S, et al. The therapeutic effect of silymarin in the treatment of nonalcoholic fatty disease: A meta-analysis (PRISMA) of randomized control trials. Medicine (Baltimore). 2017;96(49):e9061.
- Rambaldi A, Jacobs BP, Gluud C. Milk thistle for alcoholic and/or hepatitis B or C virus liver diseases. Cochrane Database Syst Rev. 2007;(4):CD003620.
- 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.
- Voroneanu L, et al. Silymarin in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Diabetes Res. 2016;2016:5147468.
- Kidd P, Head K. A review of the bioavailability and clinical efficacy of milk thistle phytosome: a silybin-phosphatidylcholine complex (Siliphos). Altern Med Rev. 2005;10(3):193-203.
- NIH National Center for Complementary and Integrative Health. Milk Thistle. Updated 2020.
- Federico A, et al. Silymarin/Silybin and Chronic Liver Disease: A Marriage of Many Years. Molecules. 2017;22(2):191.
Scores and tiers are our independent opinion, formed by applying a published rubric to label data, third-party certifications, and the research record. They are not statements of objective fact about a product and not a lab test. Where we report a brand-specific fact, it comes from a cited source or a public certification; where verification is missing, we say so rather than assume a result.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. Dietary supplements are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen.