Drug & supplement interaction

Phellodendron + Darunavir, Cobicistat

Darunavir, Cobicistat brand name: Prezcobix.

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

Phellodendron has a moderate interaction with Darunavir, Cobicistat. Theoretically, phellodendron might increase serum levels of drugs metabolized by CYP3A4.

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

Phellodendron and Darunavir, Cobicistat

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Darunavir, Cobicistat

Darunavir, Cobicistat falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Phellodendron interacts with.

Theoretically, phellodendron might increase serum levels of drugs metabolized by CYP3A4.
Phellodendron contains berberine. In vitro research and preliminary clinical research show that berberine moderately inhibits CYP3A4. Theoretically, phellodendron might also inhibit CYP3A4.
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

Your Prezcobix combo (darunavir plus cobicistat) leans heavily on the liver enzyme CYP3A4. In fact, the cobicistat part is a deliberate booster that blocks CYP3A4 so darunavir stays in your blood longer and works better. Phellodendron contains berberine, which lab and early human studies suggest can also mildly slow CYP3A4. So in theory, adding it could nudge darunavir levels a little higher and possibly bring on more side effects like nausea, diarrhea, headache, or rash.

The good news: this is only a theoretical concern based on how these compounds behave, not from real cases with this drug. Still, because keeping your HIV therapy steady and predictable matters, please check with your pharmacist or doctor before adding phellodendron rather than starting or stopping anything on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Wu X, Li Q, Xin H, Yu A, Zhong M. Effects of berberine on the blood concentration of cyclosporin A in renal transplanted recipients: clinical and pharmacokinetic study. Eur J Clin Pharmacol 2005;61:567-72. PubMed
  2. Budzinski JW, Foster BC, Vandenhoek S, Arnason JT. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82. PubMed
  3. 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
  4. 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

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 Darunavir, Cobicistat one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,159 No known interaction 1,671 (incl. Darunavir, Cobicistat)
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.

Everything else you take

See Every Supplement That Interacts With Darunavir, Cobicistat

This page covers Phellodendron only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Darunavir, Cobicistat page lists 145 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate) and Adrafinil (moderate).

By severity: 3 major · 102 moderate · 40 minor.

From our pharmacist’s overview on the Darunavir, Cobicistat page

“Prezcobix (darunavir with cobicistat) treats HIV, and it only works if it holds a steady blood level, so this list of 145 supplements deserves real care. Three carry a major rating and matter most: St.”

Reviewed by 2 · Jul 18, 2026

Open the Darunavir, Cobicistat 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 Darunavir, Cobicistat 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 Darunavir, Cobicistat 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 Darunavir, Cobicistat
Top half

#752 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 Darunavir and Cobicistat

What Is Darunavir and Cobicistat Used For?

Brand name: Prezcobix

Prezcobix and Prezcobix Ped are used to treat HIV-1 (the virus that causes AIDS) in adults and children 3 years of age and older who weigh at least 15 kg (about 33 lbs). They are always used together with other HIV medications — never alone. They are approved for people who are new to HIV treatment (treatment-naïve) as well as those who have taken HIV medicines before (treatment-experienced), as long as their virus does not have certain darunavir resistance mutations.

Prezcobix is specifically approved for adults and pediatric patients weighing at least 40 kg. Prezcobix Ped is available for smaller pediatric patients aged 3 and older weighing at least 15 kg. The right product and dose depend on the patient's weight and their ability to swallow tablets.

See full Darunavir and Cobicistat 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 Darunavir, Cobicistat, 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 Darunavir, Cobicistat supplement interactions › Every supplement checked against Darunavir, Cobicistat, ranked by severity Darunavir and Cobicistat 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 Darunavir, Cobicistat Together: Common Questions

Can you take Phellodendron with Darunavir, Cobicistat?
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.
How serious is the Phellodendron and Darunavir, Cobicistat 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 Darunavir, Cobicistat 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.