Drug & supplement interaction

Milk Thistle + Phenylephrine

Phenylephrine brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between Milk Thistle and Phenylephrine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Milk Thistle and Phenylephrine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Phenylephrine and Milk Thistle in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Milk Thistle safety at a glance

Milk Thistle overall Use caution Generally well tolerated in most adults, but quality and effectiveness vary and a doctor should be involved for liver conditions.

Pregnancy Avoid There is not enough reliable safety information, so it is best avoided during pregnancy.

Breastfeeding Use caution Safety during breastfeeding is not well studied, so caution is advised.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Phenylephrine and Milk Thistle? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

How we checked

Why No Interaction Is Listed for Phenylephrine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Phenylephrine is filed under 5 classifications — including alpha-adrenergic agonists, stimulant drugs, serotonergic drugs. Milk Thistle has documented interactions with 17 drug classes — the most serious being antidiabetes drugs (moderate), cytochrome p450 2b6 (cyp2b6) substrates (moderate) and glucuronidated drugs (moderate) — and none of Phenylephrine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Milk Thistle Does Interact With Other Medications

Milk Thistle has 254 moderate, 700 minor known drug interactions in our database — Phenylephrine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 254 Minor 700 No known interaction 1,876 (incl. Phenylephrine)

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.

What to actually watch for

No Interaction Found — But Data Suggests Milk Thistle and Phenylephrine May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

Vomiting Additional detail
Milk Thistle
“Mild gastrointestinal symptoms have been reported, including nausea, vomiting, bloating, diarrhea, epigastric pain, abdominal colic or discomfort, dyspepsia, dysgeusia, flatulence, constipation, and loss of appetite. There is one report of a 57-year-old female with sweating, nausea, colicky abdominal pain, diarrhea, vomiting, weakness, and collapse after ingesting milk thistle;”

Milk Thistle · Natural Medicines adverse-effect record, reported in constipation.
6 sources cited

2616. Ferenci P, Dragosics B, Dittrich H, et al. Randomized controlled trial of silymarin treatment in patients with cirrhosis of the liver. J Hepatol 1989;9:105-13. PubMed

6879. Anon. Milk thistle: Effects on liver disease and cirrhosis and clinical adverse effects. Summary, Evidence Report/Technology Assessment: Number 21, September 2000. Agency for Healthcare Research and Quality, Rockville, MD. Available at: http://www.ahrq.g

8956. Boerth J, Strong KM. The clinical utility of milk thistle (Silybum marianum) in cirrhosis of the liver. J Herb Pharmacother 2002;2:11-7.

13170. Tanamly MD, Tadros F, Labeeb S, et al. Randomised double-blinded trial evaluating silymarin for chronic hepatitis C in an Egyptian village: study description and 12-month results. Dig Liver Dis 2004;36:752-9. PubMed

63140. Allain, H., Schuck, S., Lebreton, S., Strenge-Hesse, A., Braun, W., Gandon, J. M., and Brissot, P. Aminotransferase levels and silymarin in de novo tacrine-treated patients with Alzheimer's disease. Dement.Geriatr.Cogn Disord. 1999;10(3):181-185. PubMed

63146. Angulo, P., Patel, T., Jorgensen, R. A., Therneau, T. M., and Lindor, K. D. Silymarin in the treatment of patients with primary biliary cirrhosis with a suboptimal response to ursodeoxycholic acid. Hepatology 2000;32(5):897-900. PubMed
Phenylephrine

Listed in the ADVERSE REACTIONS section of the FDA label for Phenylephrine. Read the label on DailyMed ›
Headache Additional detail
Milk Thistle
“With oral milk thistle use, CNS symptoms have been reported, including headache, dizziness, and sleep disturbances.”

Milk Thistle · Natural Medicines adverse-effect record, reported in cluster headache.
2 sources cited

114913. Rustamzadeh A, Sadigh N, Vahabi Z, et al. Effects silymarin and rosuvastatin on amyloid-carriers level in dyslipidemic Alzheimer's patients: A double-blind placebo-controlled randomized clinical trial. IBRO Neurosci Rep 2024;17:108-121. PubMed

114914. Fatemi Shandiz A, Karimi G, Dayyani M, Hosseini S, Elyasi S. Evaluation of oral silymarin formulation efficacy in prevention of doxorubicin induced hepatotoxicity in patients with non-metastatic breast cancer. J Oncol Pharm Pract 2024. PubMed
Phenylephrine

Listed in the ADVERSE REACTIONS section of the FDA label for Phenylephrine. Read the label on DailyMed ›
Nausea Additional detail

Milk Thistle

“Orally, milk thistle is well tolerated.

Most Common Adverse Effects:

Orally: Abdominal bloating, diarrhea, dyspepsia, flatulence, and nausea. However, these adverse effects do not typically occur at a greater frequency than with placebo.

Serious Adverse Effects (Rare):

Orally: Allergic reactions, including anaphylaxis, have been reported.”

Milk Thistle · Natural Medicines adverse-effect record, reported in diarrhea.

Phenylephrine

Listed in the ADVERSE REACTIONS section of the FDA label for Phenylephrine. Read the label on DailyMed ›

Reported for Milk Thistle but not commonly for Phenylephrine: trouble sleeping, an allergic reaction, reduced appetite and stomach pain.

Effects for Phenylephrine come from the ADVERSE REACTIONS section of its FDA label; effects for Milk Thistle come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

From our Q&A

Questions About Milk Thistle or Phenylephrine

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 Phenylephrine, 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 Phenylephrine

This page covers Milk Thistle only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenylephrine page lists 81 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Ephedra (major), Lithium (major), Peyote (major) and Rauvolfia Vomitoria (major).

By severity: 6 major · 60 moderate · 15 minor.

From our pharmacist’s overview on the Phenylephrine page

“If you take phenylephrine (Sudafed PE, Biorphen) for congestion, treat this list as one that needs real attention, since six of its 81 entries carry a major rating. Phenylephrine tightens blood vessels to clear your nose, and more than half of the interactions here come from stimulant ingredients, ephedra above all, that can push blood…”

Reviewed by 2 · Jul 18, 2026

Open the Phenylephrine 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. Even though Milk Thistle itself has no known interaction with Phenylephrine, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Milk Thistle and Phenylephrine 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%

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

29 days ago today

Medication Phenylephrine

Top 25%

#633 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.

Where does our data come from?

Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Milk Thistle reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Milk Thistle and Phenylephrine records this page draws on were last updated July 10, 2026.
What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.

Data structure & sourcing designed and verified by Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Milk Thistle

What is 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.

Silybum marianum · Asteraceae · Seeds (fruit) · Capsules, tablets, softgels, liquid extracts, tinctures, tea

An interaction check asks whether these two react with each other — it does not ask whether Milk Thistle is a good idea for someone in your situation. Here is what our Milk Thistle record says about it on its own.

Milk Thistle: dosing

There is no single official or proven dose for milk thistle. Studies have used a wide range of amounts, and products differ in how much silymarin they contain, which makes comparing doses difficult.The best approach is to follow the directions on the product label and choose a reputable brand. Look for products that list a standardized silymarin content.

From our Milk Thistle monograph — the full record covers uses, side effects and every documented interaction.

Read the full Milk Thistle monograph & all interactions

Medication

About Phenylephrine

What Is Phenylephrine Used For?

Brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen

Phenylephrine is used in a number of different forms for different purposes. Intravenous (IV) phenylephrine — including products like Biorphen and Immphentiv — is given in hospital settings to raise blood pressure in adults when it drops dangerously low due to blood vessel widening (vasodilation), such as during anesthesia. Phenylephrine Hydrochloride Injection 10 mg/mL is also approved for use in septic shock (a life-threatening infection that causes a severe drop in blood pressure).

Nasal spray and drop products (such as Neo-Synephrine and Equate Nasal) temporarily relieve nasal congestion from colds, hay fever, or upper respiratory allergies. Ophthalmic (eye drop) solutions dilate the pupil for eye exams. Rectal suppository products (such as Preparation H and ReVIVOL-XR) help relieve itching, burning, and discomfort associated with hemorrhoids.

Most-Reported Side Effects for Phenylephrine

From FAERS, the FDA’s public side-effect reporting system (221,388 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 20,609 reports

Headache 17,301 reports

Nausea 16,925 reports

Diarrhea 14,221 reports

Dyspnea 13,719 reports

See full Phenylephrine 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

700Minor

1,875No known interaction

254 Moderate 700 Minor 1,875 No interaction

Moderate

254 interactions

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

Minor

700 interactions

Showing 60 of 700 minor interactions — see all 700 on the Milk Thistle page.

No interaction 1,875 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 1,875 medications checked with no known interaction — see the full Milk Thistle list.

See the full Milk Thistle interactions page

See every supplement checked against Phenylephrine, ranked by severity

Evidence & sources

Milk Thistle References

The 69 references that drive our Milk Thistle monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

Ferenci P, Dragosics B, Dittrich H, et al. Randomized controlled trial of silymarin treatment in patients with cirrhosis of the liver. J Hepatol 1989;9:105-13. PubMed
Anon. Milk thistle: Effects on liver disease and cirrhosis and clinical adverse effects. Summary, Evidence Report/Technology Assessment: Number 21, September 2000. Agency for Healthcare Research and Quality, Rockville, MD. Available at: http://www.ahrq.g
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
Venkataramanan R, Ramachandran V, Komoroski BJ, et al. Milk thistle, a herbal supplement, decreases the activity of CYP3A4 and uridine diphosphoglucuronosyl transferase in human hepatocyte cultures. Drug Metab Dispos 2000;28:1270-3. DOI
Kim DH, Jin YH, Park JB, Kobashi K. Silymarin and its components are inhibitors of beta-glucuronidase. Biol Pharm Bull 1994;17:443-5. PubMed
Pares A, Planas R, Torres M, et al. Effects of silymarin in alcoholic patients with cirrhosis of the liver: results of a controlled, double-blind, randomized and multicenter trial. J Hepatol 1998;28:615-21. PubMed
Piscitelli SC, Formentini E, Burstein AH, et al. Effect of milk thistle on the pharmacokinetics of indinavir in healthy volunteers. Pharmacotherapy 2002;22:551-6. PubMed
Boerth J, Strong KM. The clinical utility of milk thistle (Silybum marianum) in cirrhosis of the liver. J Herb Pharmacother 2002;2:11-7.
Tanamly MD, Tadros F, Labeeb S, et al. Randomised double-blinded trial evaluating silymarin for chronic hepatitis C in an Egyptian village: study description and 12-month results. Dig Liver Dis 2004;36:752-9. PubMed
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. .
Huseini HF, Larijani B, Heshmat R, et al. The efficacy of Silybum marianum (L.) Gaertn. (silymarin) in the treatment of type II diabetes: a randomized, double-blind, placebo-controlled, clinical trial. Phytother Res 2006;20;1036-9.
Deng JW, Shon JH, Shin HJ, et al. Effect of silymarin supplement on the pharmacokinetics of rosuvastatin. Pharm Res 2008;25:1807-14. PubMed
Kim CS, Choi SJ, Park CY, et al. Effects of silybinin on the pharmacokinetics of tamoxifen and its active metabolite, 4-hydroxytamoxifen in rats. Anticancer Res 2010;30:79-85.
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
van Erp NP, Baker SD, Zhao M, et al. Effect of milk thistle (Silybum marianum) on the pharmacokinetics of irinotecan. Clin Cancer Res 2005;11:7800-6.
Budzinski JW, Trudeau VL, Drouin CE, et al. Modulation of human cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (P-gp) in Caco-2 cell monolayers by selected commercial-source milk thistle and goldenseal products. Can J Physiol Pharmacol 2007;85:966-78.
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
Jiao Z, Shi XJ, Li ZD, et al. Population pharmacokinetics of sirolimus in de novo Chinese adult renal transplant patients. Br.J.Clin.Pharmacol. 2009;68(1):47-60.
Gurley, B. J., Barone, G. W., Williams, D. K., Carrier, J., Breen, P., Yates, C. R., Song, P. F., Hubbard, M. A., Tong, Y., and Cheboyina, S. Effect of milk thistle (Silybum marianum) and black cohosh (Cimicifuga racemosa) supplementation on digoxin phar
Allain, H., Schuck, S., Lebreton, S., Strenge-Hesse, A., Braun, W., Gandon, J. M., and Brissot, P. Aminotransferase levels and silymarin in de novo tacrine-treated patients with Alzheimer's disease. Dement.Geriatr.Cogn Disord. 1999;10(3):181-185. PubMed
Angulo, P., Patel, T., Jorgensen, R. A., Therneau, T. M., and Lindor, K. D. Silymarin in the treatment of patients with primary biliary cirrhosis with a suboptimal response to ursodeoxycholic acid. Hepatology 2000;32(5):897-900. PubMed
Bean, P. The use of alternative medicine in the treatment of hepatitis C. Am.Clin.Lab 2002;21(4):19-21.
Hussain, S. A. Silymarin as an adjunct to glibenclamide therapy improves long-term and postprandial glycemic control and body mass index in type 2 diabetes. J.Med.Food 2007;10(3):543-547. PubMed
El-Kamary, S. S., Shardell, M. D., Abdel-Hamid, M., Ismail, S., El-Ateek, M., Metwally, M., Mikhail, N., Hashem, M., Mousa, A., Aboul-Fotouh, A., El-Kassas, M., Esmat, G., and Strickland, G. T. A randomized controlled trial to assess the safety and effic
Gharagozloo, M., Moayedi, B., Zakerinia, M., Hamidi, M., Karimi, M., Maracy, M., and Amirghofran, Z. Combined therapy of silymarin and desferrioxamine in patients with beta-thalassemia major: a randomized double-blind clinical trial. Fundam.Clin.Pharmaco
Ladas, E. J., Kroll, D. J., Oberlies, N. H., Cheng, B., Ndao, D. H., Rheingold, S. R., and Kelly, K. M. A randomized, controlled, double-blind, pilot study of milk thistle for the treatment of hepatotoxicity in childhood acute lymphoblastic leukemia (ALL PubMed
Sayyah, M., Boostani, H., Pakseresht, S., and Malayeri, A. Comparison of Silybum marianum (L.) Gaertn. with fluoxetine in the treatment of Obsessive-Compulsive Disorder. Prog.Neuropsychopharmacol.Biol.Psychiatry 3-17-2010;34(2):362-365. PubMed
Flaig, T. W., Glode, M., Gustafson, D., van, Bokhoven A., Tao, Y., Wilson, S., Su, L. J., Li, Y., Harrison, G., Agarwal, R., Crawford, E. D., Lucia, M. S., and Pollak, M. A study of high-dose oral silybin-phytosome followed by prostatectomy in patients w
Ramirez-Santos, A., Perez-Bustillo, A., Gonzalez-Sixto, B., Suarez-Amor, O., and Rodriguez-Prieto, M. A. [Acute generalized exanthematous pustulosis due to milk thistle (Silybum marianum) tea]. Actas Dermosifiliogr. 2011;102(9):744-745. DOI
Loguercio C, Andreone P, Brisc C, et al. Silybin combined with phosphatidylcholine and vitamin E in patients with nonalcoholic fatty liver disease: a randomized controlled trial. Free Radic Biol Med 2012;52(9):1658-65. PubMed
Yakoot, M. and Salem, A. Spirulina platensis versus silymarin in the treatment of chronic hepatitis C virus infection. A pilot randomized, comparative clinical trial. BMC.Gastroenterol. 2012;12:32. PubMed
Fallahzadeh, M. K., Dormanesh, B., Sagheb, M. M., Roozbeh, J., Vessal, G., Pakfetrat, M., Daneshbod, Y., Kamali-Sarvestani, E., and Lankarani, K. B. Effect of addition of silymarin to renin-angiotensin system inhibitors on proteinuria in type 2 diabetic
Fried, M. W., Navarro, V. J., Afdhal, N., Belle, S. H., Wahed, A. S., Hawke, R. L., Doo, E., Meyers, C. M., and Reddy, K. R. Effect of silymarin (milk thistle) on liver disease in patients with chronic hepatitis C unsuccessfully treated with interferon t
Fallah Huseini, H., Larijani, B., Fakhrzadeh, H., Rajabi Pour, B., Akhondzadeh, S., Toliat, T., and Heshmat, R. The clinical trial of Silybum Marianum seed extract (Silymarin) on type II diabetic patients with hyperlipidemia. Iran J.Diabetes Lipid Disord
Mironets VI, Krasovskaia EA, and Polishchuk II. [A case of urticaria during Carsil treatment]. Vrach Delo 1990;7:86-87.
Velussi M, Cernigoi AM, Viezzoli L, and et al. Silymarin reduces hyperinsulinemia, malondialdehyde levels, and daily insulin need in cirrhotic diabetic patients. Curr Ther Res 1993;53(5):533-545. DOI
Marcelli R, Bizzoni P, Conte D, and et al. Randomized controlled study of the efficacy and tolerability of a short course of IdB 1016 in the treatment of chronic persistent hepatitis. Eur Bull Drug Res 1992;1(3):131-135.
Vailati A, Aristia L, Sozze E, and et al. Randomized open study of the dose-effect relationship of a short course of IdB 1016 in patients with viral or alcoholic hepatitis. Fitoterapia 1993;64(3):219-228.
Marena C and Lampertico M. Preliminary clinical development of silipide: a new complex of silybin in toxic liver disorders. Planta Med 1991;57(2):A124-A125. DOI
Grungreiff K, Albrecht M, and Strenge-Hesse A. Benefit of medicinal liver therapy in general practice. Med Welt 1995;46:222-227.
Frerick F, Kuhn U, and Strenge-Hesse A. Silymarin--ein Phytopharmakon zur Behandlung toxischen Leberschaden: Anwendungsbeobachtung bei 2169 Patienten. Kassenarzt 1990;33:36-41.
Schuppan D, Strosser W, Burkard G, and et al. Influence of Legalon(TM) 140 on the metabolism of collagen in patients with chronic liver disease--Review by measurement of PIIINP-values. Zeitschrift fur Allgemeinmedizin 1998;74:577-584.
Studlar M. Die Behandlung chronischer Leberkrankungen mit Silymarin und B-Vitaminen. Therapiewoche 1985;35:3375-3378.
Anon. Adverse reaction: milk thistle-associated toxicity. Nurse Drug Alert 1999;23(7):51.
Gufford BT, Chen G, Vergara AG, et al. Milk Thistle Constituents Inhibit Raloxifene Intestinal Glucuronidation: A Potential Clinically Relevant Natural Product-Drug Interaction. Drug Metab Dispos. 2015;43(9):1353-9. PubMed
El-Shitany NA, Hegazy S, El-Desoky K. Evidences for antiosteoporotic and selective estrogen receptor modulator activity of silymarin compared with ethinylestradiol in ovariectomized rats. Phytomedicine. 2010;17(2):116-25. PubMed
Seidlová-Wuttke D, Becker T, Christoffel V, Jarry H, Wuttke W. Silymarin is a selective estrogen receptor beta (ERbeta) agonist and has estrogenic effects in the metaphysis of the femur but no or antiestrogenic effects in the uterus of ovariectomized (ovx
Jalloh MA, Gregory PJ, Hein D, et al. Dietary supplement interactions with antiretrovirals: a systematic review. Int J STD AIDS. 2017 Jan;28(1):4-15. PubMed
Derosa G, Romano D, D'Angelo A, Maffioli P. Berberis aristata/Silybum marianum fixed combination (Berberol(®)) effects on lipid profile in dyslipidemic patients intolerant to statins at high dosages: a randomized, placebo-controlled, clinical trial. Phyto PubMed
Luangchosiri C, Thakkinstian A, Chitphuk S, Stitchantrakul W, Petraksa S, Sobhonslidsuk A. A double-blinded randomized controlled trial of silymarin for the prevention of antituberculosis drug-induced liver injury. BMC Complement Altern Med. 2015;15:334. PubMed
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
Rastegarpanah M, Malekzadeh R, Vahedi H, et al. A randomized, double blinded, placebo-controlled clinical trial of silymarin in ulcerative colitis. Chin J Integr Med. 2015;21(12):902-6. PubMed
Di Pierro F, Bellone I, Rapacioli G, Putignano P. Clinical role of a fixed combination of standardized Berberis aristata and Silybum marianum extracts in diabetic and hypercholesterolemic patients intolerant to statins. Diabetes Metab Syndr Obes. 2015;8:8 PubMed
Di Pierro F, Villanova N, Agostini F, Marzocchi R, Soverini V, Marchesini G. Pilot study on the additive effects of berberine and oral type 2 diabetes agents for patients with suboptimal glycemic control. Diabetes Metab Syndr Obes. 2012;5:213-7. PubMed
Guarino G, Strollo F, Carbone L, et al. Bioimpedance analysis, metabolic effects and safety of the association Berberis aristata/Bilybum marianum: a 52-week double-blind, placebo-controlled study in obese patients with type 2 diabetes. J Biol Regul Homeos
Ebrahimpour-Koujan S, Gargari BP, Mobasseri M, Valizadeh H, Asghari-Jafarabadi M. Lower glycemic indices and lipid profile among type 2 diabetes mellitus patients who received novel dose of Silybum marianum (L.) Gaertn. (silymarin) extract supplement: A T
Lash DB, Ward S. CYP2C9-mediated warfarin and milk thistle interaction. J Clin Pharm Ther. 2019. PubMed
Malekshah RE, Khaleghian A. Influence of Silybum marianum on morphine addicted rats, biochemical parameters and molecular simulation studies on µ-opioid receptor. Drug Res (Stuttg). 2019;69(11):630-638. PubMed
Soleymani S, Ayati MH, Mansourzadeh MJ, Namazi N, Zargaran A. The effects of Silymarin on the features of cardiometabolic syndrome in adults: A systematic review and meta-analysis. Phytother Res. 2022 Jan 11. doi: 10.1002/ptr.7364. PubMed
Gamissans M, Expósito-Serrano V, López-Llunell C, Valdivieso L, Garbayo-Salmons P. Bullous pemphigoid triggered by Silybum marianum: an unexpected side effect of an herbal remedy. Int J Dermatol. 2021 Aug 7. doi: 10.1111/ijd.15822. PubMed
Aboras SI, Korany MA, El-Yazbi AF, Ragab MAA, Abdine HH. In-depth investigation of the Silymarin effect on the pharmacokinetic parameters of sofosbuvir, GS-331007 and ledipasvir in rat plasma using LC-MS. Biomed Chromatogr 2022;36(9):e5427. PubMed
Wattanakrai P, Nimmannitya K. A Randomized, Double-Blind, Split-Face Study of Topical Silymarin vs 2% Hydroquinone Cream in Melasmas. J Drugs Dermatol 2022;21(12):1304-1310. PubMed
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
Zhang W, Zhang Y, Wen C, Jiang X, Wang L. In vitro Assessment of the Effects of Silybin on CYP2B6-mediated Metabolism. Planta Med 2023. PubMed
Bechtold BJ, Lynch KD, Oyanna VO, et al. Rifampin- and Silymarin-Mediated Pharmacokinetic Interactions of Exogenous and Endogenous Substrates in a Transgenic OATP1B Mouse Model. Mol Pharm 2024;21(5):2284-2297. PubMed
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Rustamzadeh A, Sadigh N, Vahabi Z, et al. Effects silymarin and rosuvastatin on amyloid-carriers level in dyslipidemic Alzheimer's patients: A double-blind placebo-controlled randomized clinical trial. IBRO Neurosci Rep 2024;17:108-121. PubMed
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Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Milk Thistle and Phenylephrine Together: Common Questions

Is it safe to take Milk Thistle with Phenylephrine?

We do not list a known interaction between Milk Thistle and Phenylephrine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.

Do Milk Thistle and Phenylephrine have any of the same side effects?

Yes — our sources link each of them separately to 3 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.

How was the Milk Thistle and Phenylephrine combination checked?

Interactions in our licensed database are recorded against drug classes. Phenylephrine is filed under 5 classifications, and Milk Thistle has documented interactions with 17 drug classes — none of Phenylephrine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.

Does Milk Thistle interact with any other medications?

Yes. Milk Thistle has 954 documented drug interactions in our database — Phenylephrine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.

Does Phenylephrine interact with any supplements?

Yes. Phenylephrine has documented interactions with 81 supplements in our database — Milk Thistle is not one of them. The Phenylephrine interaction page linked on this page lists every one, ranked by severity.

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

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Milk Thistle monograph Uses, safety profile, and every drug interaction in one place Phenylephrine drug information The full plain-English guide to this medication Phenylephrine supplement interactions Every supplement checked against Phenylephrine, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 69 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

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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.