Guide
Can you take milk thistle and magnesium together?
No trial has tested milk thistle and magnesium taken together, and neither ingredient's own research flags an interaction with the other. They're an essential mineral and a plant extract studied for different things, sold together in some formulas by marketing choice rather than tested combination.
No trial has tested milk thistle and magnesium together as a supplement combination, and neither ingredient's own safety research flags an interaction with the other. They're unrelated substances — an essential mineral and a plant extract — and nothing in either one's research documents a conflict between them.
What each one is
Magnesium is an essential mineral, sold in several compound forms (glycinate, citrate, oxide and others) that differ in absorption and gastrointestinal tolerance. The number that matters on a label is elemental magnesium — the actual mineral amount your body counts — not the total compound weight, per NIH's Office of Dietary Supplements. Milk thistle is a plant extract standardized to silymarin, with no established RDA; its own research is covered in milk thistle benefits: what the research does and doesn't show.
Is there a known interaction?
Milk thistle's own interaction research is small and specific: one human trial found a genotype-dependent effect on a blood-pressure medication's levels, and a separate trial found no significant effect on four major drug-processing liver enzymes. Neither trial, nor any other research we found on milk thistle, tested or flagged an interaction with magnesium. See milk thistle and medications: what to check for what that research does cover.
"Magnesium stearate" isn't a magnesium dose
Magnesium stearate is a common capsule-manufacturing lubricant, used in tiny amounts to keep powder from sticking to equipment — it's listed on a label's "other ingredients" line, not as a magnesium supplement serving, and it isn't the same thing as taking a magnesium supplement. A milk thistle product that lists magnesium stearate as an "other ingredient" isn't providing a meaningful magnesium dose; if you're looking for a milk thistle product without it, that's a manufacturing-process preference, not a magnesium-interaction question.
Questions people ask
Can you take milk thistle and magnesium together?
No trial has tested the combination directly, but nothing in either ingredient's own research documents a conflict between them. If you take a prescription medication or have a diagnosed liver or kidney condition, mention both supplements to a doctor before combining them.
Is milk thistle without magnesium stearate available?
Some products use it as a manufacturing lubricant and others don't — check the "other ingredients" line on a specific label. It's a formulation detail, not related to whether a product is safe to combine with a magnesium supplement.
Does milk thistle affect magnesium absorption, or the reverse?
No research we found measures that specifically. The two are chemically and functionally unrelated, so there's no known mechanism by which one would be expected to change the other, but "no known mechanism" isn't the same as a trial confirming no interaction.
Related reading: milk thistle and medications: what to check, milk thistle without fillers, and milk thistle benefits: what the research does and doesn't show.
Sources
- Effect of silymarin on the pharmacokinetics of losartan and its active metabolite E-3174 in healthy Chinese volunteers A 2009 trial found that 420 mg/day of silymarin for 14 days changed losartan blood levels in healthy volunteers, but the effect depended on the person's CYP2C9 genotype.
- Milk Thistle An NIH reference monograph reports no valid clinical trial support for milk thistle increasing milk supply, describes it as generally well tolerated with occasional GI/skin side effects, and flags rare but real allergic cross-reactivity with ragweed-family plants.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.