Drug & supplement interaction

Phellodendron + Carvedilol

Carvedilol brand names: Coreg, Coreg CR.

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

Carvedilol falls into 3 drug categories that Phellodendron can interact with; the most serious is rated moderate. Theoretically, phellodendron might have additive effects with antihypertensive drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Phellodendron and Carvedilol

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Phellodendron interacts with whole categories of medication. Carvedilol falls into 3 of those categories, so it can interact with Phellodendron in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

ANTIHYPERTENSIVE DRUGS

1 of 3

Why this applies to Carvedilol

Carvedilol falls under ANTIHYPERTENSIVE DRUGS — the group Phellodendron interacts with.

Theoretically, phellodendron might have additive effects with antihypertensive drugs.
Phellodendron contains berberine. Animal research suggests that berberine can have hypotensive effects. Also, a clinical study suggests that taking berberine in combination with amlodipine can lower systolic and diastolic blood pressure when compared with amlodipine alone. Theoretically, phellodendron might also reduce blood pressure.
Severity Moderate Likelihood Possible Evidence D

Interaction 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.

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

Here's the simple version: Carvedilol already lowers your blood pressure and slows your heart rate, and Phellodendron (because of the berberine it contains) may nudge blood pressure down a little on its own. Stacking the two together could add up, so your readings might drop more than expected.

If that happens, you may notice dizziness, lightheadedness, feeling tired, or a slow heartbeat, especially when you stand up quickly. I want to be honest though, this concern is mostly theoretical and based on animal studies plus one trial using berberine with a different blood pressure drug, not Carvedilol itself. It's not a sure thing. Still, since both can affect blood pressure, check with your pharmacist or doctor before combining them, and don't change your Carvedilol on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Sabir M and Bhide NK. Study of some pharmacological actions of berberine. Ind J Physiol & Pharmac 1971;15(3):111-132.
  2. Chun YT, Yip TT, Lau KL, and et al. A biochemical study on the hypotensive effect of berberine in rats. Gen Pharmac 1979;10:177-182. PubMed
  3. Lan J, Zhao Y, Dong F, et al. Meta-analysis of the effect and safety of berberine in the treatment of type 2 diabetes mellitus, hyperlipemia and hypertension. J Ethnopharmacol. 2015;161:69-81. PubMed
Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

2 of 3

Carvedilol also falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES.

Theoretically, phellodendron might increase serum levels of drugs metabolized by CYP2D6.
Phellodendron contains berberine. In vitro research and preliminary clinical evidence show that berberine can inhibit CYP2D6. Theoretically, phellodendron might also inhibit CYP2D6.
Severity Moderate Likelihood Possible Evidence D

Interaction 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.

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

Here's the gist: your body uses a liver enzyme called CYP2D6 to help break down carvedilol. Phellodendron contains berberine, which lab studies and some early human data suggest can slow that enzyme down. If carvedilol clears more slowly, more of it can hang around in your blood, which could make its effects stronger than expected.

With carvedilol, that might show up as extra low blood pressure, a slower heart rate, dizziness, or feeling more tired or lightheaded, especially when you stand up. The good news is this interaction is mostly theoretical right now, so it isn't a sure thing. Still, since carvedilol works on your heart and blood pressure, don't start or stop anything on your own. Check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chatterjee P, Franklin MR. Human cytochrome p450 inhibition and metabolic-intermediate complex formation by goldenseal extract and its methylenedioxyphenyl components. Drug Metab Dispos 2003;31:1391-7. PubMed
  2. Guo, Y., Chen, Y., Tan, Z. R., Klaassen, C. D., and Zhou, H. H. Repeated administration of berberine inhibits cytochromes P450 in humans. Eur J Clin Pharmacol 2012;68(2):213-217. PubMed
  3. Hermann, R. and von, Richter O. Clinical evidence of herbal drugs as perpetrators of pharmacokinetic drug interactions. Planta Med 2012;78(13):1458-1477. PubMed
Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

3 of 3

Carvedilol also falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES.

Theoretically, phellodendron might increase serum levels of drugs metabolized by CYP2C9.
Phellodendron contains berberine. Preliminary clinical research shows that berberine can inhibit CYP2C9. Theoretically, phellodendron might also inhibit CYP2C9.
Severity Moderate Likelihood Possible Evidence D

Interaction 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.

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

Here's the simple version. Your body uses a liver enzyme called CYP2C9 to help break down carvedilol. Phellodendron contains berberine, and early research hints that berberine may slow that enzyme down. If that happens, carvedilol could clear out a little more slowly and build up in your blood, making its effects stronger.

Carvedilol is not a prodrug, so more of it in your system means more of its usual actions: lower blood pressure, a slower heart rate, and possibly more dizziness, lightheadedness, or fatigue. I want to be honest though, this concern is theoretical and based on how the enzyme works, not solid human studies. It's still worth mentioning to your pharmacist or doctor before you combine them so they can keep an eye on your blood pressure and pulse.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Guo, Y., Chen, Y., Tan, Z. R., Klaassen, C. D., and Zhou, H. H. Repeated administration of berberine inhibits cytochromes P450 in humans. Eur J Clin Pharmacol 2012;68(2):213-217. 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

Phellodendron Also Interacts With Other Medications

Phellodendron has 1,159 moderate known drug interactions in our database — the Carvedilol one above is among them. If you take anything else, check it against the full list below.

Moderate 1,159 No known interaction 1,671 (incl. Carvedilol)
Taking anything else?

Check Another of Your Medications Against Phellodendron

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

From our Q&A

Questions About Phellodendron or Carvedilol

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Phellodendron or Carvedilol, 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 Carvedilol

This page covers Phellodendron only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Carvedilol page lists 211 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Grapefruit (major) and Indian Snakeroot (major).

By severity: 6 major · 171 moderate · 34 minor.

From our pharmacist’s overview on the Carvedilol page

“People take carvedilol (Coreg) for heart failure and high blood pressure, conditions where a sudden swing in pressure or heart rate matters, and its supplement list runs to 211 ingredients, so this one calls for genuine care. More than half of those entries lower blood pressure on their own, fish oil and celery seed among them, and can…”

Reviewed by 2 · Jul 18, 2026

Open the Carvedilol interaction page

One more smart check

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

We hold 393 real supplement products containing Phellodendron, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Phellodendron. Your product may carry other ingredients that interact with Carvedilol too, on top of Phellodendron — 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 Phellodendron and Carvedilol 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 Phellodendron
Top 25%

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

29 days ago today
Medication Carvedilol
Top 10%

#256 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 Phellodendron

What is Phellodendron?

Phellodendron
  • Digestive complaints and diarrhea
  • Inflammation and joint discomfort
  • Stress and weight management (in combination products)
  • Skin conditions (topical, traditional)
  • Antimicrobial support

Phellodendron is a traditional Chinese medicine bark (Huang Bai) that contains berberine and other plant compounds with antimicrobial and anti-inflammatory activity in lab studies. Human evidence for most uses is limited, and it is often sold in combination with other herbs, making its individual effects hard to judge. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Read the full Phellodendron monograph & all interactions
Medication

About Carvedilol

What Is Carvedilol Used For?

Brand names: Coreg, Coreg CR

Carvedilol is used to treat three main conditions: mild-to-severe chronic heart failure, high blood pressure (hypertension), and reduced heart pumping function (left ventricular dysfunction) in people who have survived a heart attack. For heart failure, it is usually prescribed alongside other medications such as diuretics, ACE inhibitors, and digitalis to help people live longer and reduce the chance of hospital stays.

For people who have had a heart attack and whose heart is not pumping as well as it should, carvedilol is used to lower the risk of dying from heart-related causes. For high blood pressure, it can be used on its own or combined with other blood pressure medicines.

See full Carvedilol drug information
Keep checking

Other Drugs & Phellodendron

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

0Major
1,159Moderate
0Minor
1,670No known interaction
1,159 Moderate 1,670 No interaction
Moderate

1,159 interactions

Showing 60 of 1,159 moderate interactions — see all 1,159 on the Phellodendron page.

No interaction 1,670 drugs checked — show the list

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

Showing the 60 most looked-up of 1,670 medications checked with no known interaction — see the full Phellodendron list.

See the full Phellodendron interactions page
See every supplement checked against Carvedilol, 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
Phellodendron monograph › Uses, safety, and every drug interaction in one place Carvedilol supplement interactions › Every supplement checked against Carvedilol, ranked by severity Carvedilol 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 Phellodendron and Carvedilol Together: Common Questions

Can you take Phellodendron with Carvedilol?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 3 interactions listed for Phellodendron and Carvedilol?
Carvedilol belongs to more than one drug category, and Phellodendron interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Phellodendron and Carvedilol interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Carvedilol and Phellodendron?

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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.