Guide
Milk thistle and fish oil: can you take them together?
No trial has tested milk thistle and fish oil taken together. Nothing in either ingredient's documented safety research flags a problem with combining them, but that's an absence of data rather than a tested combination, and each is studied in a different area — milk thistle for liver and kidney markers, fish oil mostly for cardiovascular and inflammatory markers.
No trial has tested milk thistle and fish oil taken together. Nothing in either ingredient's documented safety research flags a problem with combining them, but that's an absence of data, not a tested combination — and the two are studied in entirely different areas.
No combined research, and no documented interaction
Milk thistle's human trials are concentrated on people already diagnosed with a liver condition, with a smaller body of research in diabetic kidney disease — a 2017 pooled analysis of 6 trials in liver disease, for example, measured liver enzyme changes, not anything related to omega-3 fatty acids. Fish oil's research base is mostly about cardiovascular and inflammatory markers. Neither ingredient's trials tested the other, and no study has combined the two to look for an interaction, positive or negative.
Forms and timing
Milk thistle is typically taken as a standardized extract in a capsule or tablet; fish oil is typically a softgel. Neither form has a documented interaction with the other, and both are commonly taken with food, which is standard advice for fat-soluble compounds and to reduce stomach upset — not evidence of a combined effect between the two.
Where each ingredient's own safety notes live
Fish oil has its own safety and interaction guidance, covered on its own page rather than here. Milk thistle's own interaction research is a small, inconsistent set of studies on liver-enzyme metabolism and one specific blood-pressure drug, and no trial we found shows milk thistle acting as a blood thinner. See fish oil side effects and milk thistle and medications: what to check for what each ingredient's own safety research covers.
Questions people ask
Is it safe to take milk thistle and fish oil together?
Nothing in either ingredient's documented research flags a specific problem with combining them, but no trial has tested the combination directly, so that's not a tested guarantee.
Does milk thistle affect how fish oil works?
No trial has tested that question. The two haven't been studied together, and nothing in milk thistle's research describes an effect on fatty-acid metabolism.
Related reading: milk thistle benefits: what the research does and doesn't show and fish oil benefits: what the research does and doesn't show.
Sources
- Effect of silymarin on biochemical indicators in patients with liver disease: Systematic review with meta-analysis A 2017 pooled analysis of 6 trials in people with liver disease found silymarin lowered ALT and AST by a statistically significant but clinically negligible amount, with no change in gamma-GT.
*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.