Does milk thistle help with blood pressure? What the research does and doesn't show

The evidence doesn't support milk thistle as a treatment for high blood pressure. A 2024 pooled analysis of 33 trials found a small diastolic blood pressure drop with silymarin versus placebo, and no significant difference in systolic pressure; separately, a 2009 trial found silymarin changed blood levels of one blood pressure drug, in a genotype-dependent way.

What the evidence doesn't support

It doesn't support milk thistle or silymarin as a treatment for high blood pressure, hypertension or any other diagnosed cardiovascular condition, and it doesn't support taking it in place of a prescribed blood pressure medication. No trial has tested milk thistle for blood pressure in a healthy general population — the trials pooled below were run mostly in adults research describes as having a cardiometabolic condition. Nothing here describes a specific product's dose, and nothing here is a claim about any product.

What the trials found

A 2024 systematic review and dose-response meta-analysis pooled 33 controlled trials (1,943 participants) looking at silymarin's effect on cardiovascular risk factors, including blood pressure. Diastolic blood pressure came out about 1.25 mmHg lower with silymarin than with placebo across the pooled trials — a modest, statistically significant difference — while systolic blood pressure didn't differ significantly between the two groups. The abstract doesn't break out results by each trial's specific diagnosis, though the wider silymarin literature is concentrated in people with diabetes, fatty liver disease or another metabolic risk factor, not a general population managing ordinary blood pressure. The authors say the overall findings need confirming in larger, longer trials.

Separate from blood pressure as an outcome, a 2009 crossover trial in 12 healthy men measured how silymarin affects the blood-pressure drug losartan. After 14 days of 420 mg/day silymarin, losartan blood levels rose in people with one CYP2C9 genotype but not another, and levels of losartan's active metabolite fell in both genotype groups. That's a documented drug interaction, not a blood-pressure effect of milk thistle by itself, and it's the clearest reason someone on blood pressure medication should check with a doctor before adding milk thistle rather than a reason to expect a blood-pressure benefit.

Trial	Population	Result
Mohammadi 2024 (33 pooled trials, n=1,943)	Adults with cardiometabolic risk factors (diagnosis not broken out in abstract)	Diastolic BP modestly lower with silymarin; systolic BP not significantly different
Han 2009 (n=12)	Healthy men, by CYP2C9 genotype	Silymarin changed losartan blood levels, genotype-dependent

Questions people ask

Can milk thistle lower blood pressure?

A 2024 pooled analysis found a small, statistically significant drop in diastolic blood pressure with silymarin, and no significant change in systolic blood pressure. It wasn't tested in a general healthy population, and the authors call the finding preliminary.

Can milk thistle raise blood pressure?

No trial reviewed here found silymarin raising blood pressure directly. The documented interaction is with a blood pressure medication's blood levels, not with blood pressure itself.

Does milk thistle interact with blood pressure medication?

Yes, at least with losartan: a 2009 trial found silymarin changed losartan's blood levels, and the effect depended on the person's genotype. See milk thistle and medications: what to check for the full picture, including drug interactions the human data doesn't confirm.

When to talk to a doctor

Anyone with diagnosed high blood pressure should manage it with a doctor's guidance; milk thistle is not a treatment for hypertension, and the trials above were run alongside standard care, not instead of it. If you take a blood pressure medication, ask a doctor before adding milk thistle.

Related reading: milk thistle and medications: what to check, milk thistle and cholesterol, and what is milk thistle.