Drug & supplement interaction

Milk Thistle + Ibuprofen

Ibuprofen brand names: Motrin, Children's Motrin, Advil, Children's Advil, Fenbid Forte Gel, and others.

Minor Interaction
Medically reviewed by · Updated September 2026
The bottom line Minor

Milk Thistle has a minor interaction with Ibuprofen. It is unclear if milk thistle inhibits CYP2C9; research is conflicting.

Read the full interaction report
SeverityMinor
LikelihoodUnlikely
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Milk Thistle and Ibuprofen

Here is the interaction we found between these two, with the evidence behind it.

Minor

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

Why this applies to Ibuprofen

Ibuprofen falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES — the group Milk Thistle interacts with.

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.
Severity Minor Likelihood Unlikely Evidence B

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist for ibuprofen and milk thistle. Your liver uses an enzyme called CYP2C9 to help clear ibuprofen out of your system. In test-tube studies, milk thistle (silymarin) might slow that enzyme down a bit. If that happened, ibuprofen could hang around a little longer and you could see more of its usual side effects, things like stomach upset, heartburn, or in rare cases stomach irritation.

The honest takeaway, though, is that the human evidence here is weak and conflicting. Some studies show milk thistle doesn't meaningfully change CYP2C9 at all, so for most people this is unlikely to cause a real problem. Still, if you take ibuprofen often or use milk thistle daily, it's worth a quick chat with your pharmacist or doctor to be safe.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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
  2. 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. .
  3. 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
  4. Doehmer J, Weiss G, McGregor GP, Appel K. Assessment of a dry extract from milk thistle (Silybum marianum) for interference with human liver cytochrome-P450 activities. Toxicol In Vitro 2011;25:21-7. PubMed
  5. Kawaguchi-Suzuki M, Frye RF, Zhu HJ, et al. The effects of milk thistle (Silybum marianum) on human cytochrome P450 activity. Drug Metab Dispos. 2014;42(10):1611-6. PubMed
  6. Pochet S, Lechon AS, Lescrainier C, et al. Herb-anticancer drug interactions in real life based on VigiBase, the WHO global database. Sci Rep 2022;12(1):14178. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Milk Thistle Also Interacts With Other Medications

Milk Thistle has 254 moderate, 699 minor known drug interactions in our database — the Ibuprofen one above is one of them. If you take anything else, check it against the full list below.

Moderate 254 Minor 699 No known interaction 1,877 (incl. Ibuprofen)
Taking anything else?

Check Another of Your Medications Against Milk Thistle

Covers the 2,830 medications we’ve checked against Milk Thistle. Pick one to open its full report.

From our Q&A

Questions About Milk Thistle or Ibuprofen

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Milk Thistle or Ibuprofen, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Ibuprofen

This page covers Milk Thistle only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ibuprofen page lists 286 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Danshen (major) and Piracetam (major).

By severity: 7 major · 243 moderate · 36 minor.

From our pharmacist’s overview on the Ibuprofen page

“Most people treat ibuprofen (Advil, Motrin) as an everyday pain reliever, which is exactly why this list of 286 interacting supplements deserves real attention rather than a shrug. The dominant pattern by far is bleeding: 202 of these ingredients can add to the bleeding and stomach irritation ibuprofen already causes, and the seven maj…”

Reviewed by 2 · Jul 18, 2026

Open the Ibuprofen interaction page

One more smart check

Taking Milk Thistle as Part of a Dietary Supplement Product? Check It for Interactions

We hold 4,560 real supplement products containing Milk Thistle, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Milk Thistle. Your product may carry other ingredients that interact with Ibuprofen too, on top of Milk Thistle — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Milk Thistle and Ibuprofen Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Milk Thistle
Top 5%

#49 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Ibuprofen
Top 1%

#19 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Milk Thistle

What is Milk Thistle?

Milk Thistle
  • Liver health and protection
  • Hepatitis
  • Cirrhosis
  • Gallbladder problems
  • High cholesterol
  • Type 2 diabetes support

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.

Read the full Milk Thistle monograph & all interactions
Medication

About Ibuprofen

What Is Ibuprofen Used For?

Brand names: Motrin, Children's Motrin, Advil, Children's Advil, Fenbid Forte Gel, Ibugel Forte, Arthrofen, Ebufac, Rimafen, Calprofen, Fenpaed, Galprofen, Nurofen for Children, Orbifen for Children, Brufen, Brufen Retard, Fenbid, Tab-Profen, Ibuprofen, Calodor

Oral ibuprofen products (tablets, coated tablets, and liquid-filled capsules) are used to temporarily relieve minor aches and pains from headache, backache, toothache, muscular aches, menstrual cramps, minor arthritis pain, and the common cold, and to temporarily reduce fever. The oral prescription tablet (Ibu) is also indicated for the signs and symptoms of rheumatoid arthritis and osteoarthritis, mild to moderate pain, and primary dysmenorrhea (painful periods).

Caldolor, an intravenous (IV) form, is approved for adults and children 3 months and older to manage mild to moderate pain, to manage moderate to severe pain alongside opioid pain medicines, and to reduce fever. A separate intravenous solution, Ibuprofen Lysine, is used specifically in premature infants to close a patent ductus arteriosus (PDA) — an abnormal blood vessel connection near the heart — when standard medical management has not worked.

See full Ibuprofen drug information
Keep checking

Other Drugs & Milk Thistle

Browse every other medication we’ve checked against Milk Thistle — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
254Moderate
699Minor
1,876No known interaction
254 Moderate 699 Minor 1,876 No interaction
Moderate

254 interactions

Showing 60 of 254 moderate interactions — see all 254 on the Milk Thistle page.

Minor

699 interactions

Showing 60 of 699 minor interactions — see all 699 on the Milk Thistle page.

No interaction 1,876 drugs checked — show the list

We also checked Milk Thistle against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,876 medications checked with no known interaction — see the full Milk Thistle list.

See the full Milk Thistle interactions page
See every supplement checked against Ibuprofen, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

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

Keep exploring
Milk Thistle monograph › Uses, safety, and every drug interaction in one place Ibuprofen supplement interactions › Every supplement checked against Ibuprofen, ranked by severity Ibuprofen drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Milk Thistle and Ibuprofen Together: Common Questions

Can you take Milk Thistle with Ibuprofen?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Milk Thistle and Ibuprofen interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Ibuprofen and Milk Thistle?

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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.