Drug & supplement interaction

Uva Ursi + Belzutifan

Belzutifan brand name: Welireg.

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

Belzutifan falls into 2 drug categories that Uva Ursi can interact with; the most serious is rated moderate. Theoretically, uva ursi may decrease the metabolism of CYP2C19 substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Uva Ursi and Belzutifan

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Uva Ursi interacts with whole categories of medication. Belzutifan falls into 2 of those categories, so it can interact with Uva Ursi in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

1 of 2

Why this applies to Belzutifan

Belzutifan falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES — the group Uva Ursi interacts with.

Theoretically, uva ursi may decrease the metabolism of CYP2C19 substrates.
In vitro, uva ursi appears to inhibit cytochrome CYP2C19. This effect has not been reported in humans.
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 for Welireg (belzutifan). Your body relies partly on a liver enzyme called CYP2C19 to clear this medicine out. Uva ursi, in lab testing, seems to slow that same enzyme down. If that held true in people, belzutifan could build up a bit more than expected, and that can mean stronger side effects like anemia (low red blood cells causing tiredness or shortness of breath) and low oxygen levels, which are already known concerns with this drug.

I want to be honest though: this is only seen in a test tube, never confirmed in actual patients, so it's more of a theoretical caution than a proven problem. Since belzutifan treats serious cancer, don't change anything on your own. Just give your oncologist or pharmacist a heads-up before adding uva ursi.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chauhan B, Yu C, Krantis A, et al. In vitro activity of uva-ursi against cytochrome P450 isoenzymes and P-glycoprotein. Can J Physiol Pharmacol. 2007;85(11):1099-107.
Moderate

GLUCURONIDATED DRUGS

2 of 2

Belzutifan also falls under GLUCURONIDATED DRUGS.

Theoretically, uva ursi may increase levels of drugs metabolized by glucuronidation.
In vitro, uva ursi extract appears to strongly inhibit UDP-glucuronosyltransferase (UGT) 1A1 (UGT1A1). However, uva ursi extract does not appear to inhibit UGT1A1 in animal models. This effect has not been reported in humans.
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 short version: your body clears belzutifan partly by attaching a sugar molecule to it (a process called glucuronidation, handled by an enzyme called UGT1A1). In a test-tube study, uva ursi blocked that enzyme fairly strongly. If that were to happen in real life, belzutifan could build up and you might see more of its usual side effects, like anemia (feeling tired, short of breath, pale) and low oxygen levels in the blood.

But I want to be honest about the evidence. This concern comes only from lab studies, and animal studies did not show the same blocking effect. It has never been reported in actual people. So the worry is theoretical, not proven. Still, because belzutifan is a serious cancer medication, please run any uva ursi use by your oncology team or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Park JB, Kim D, Min JS, et al. Identification and characterization of in vitro inhibitors against UDP-glucuronosyltransferase 1A1 in uva-ursi extracts and evaluation of in vivo uva-ursi-drug interactions. Food Chem Toxicol. 2018;120:651-661. 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

Uva Ursi Also Interacts With Other Medications

Uva Ursi has 739 moderate, 63 minor known drug interactions in our database — the Belzutifan one above is among them. If you take anything else, check it against the full list below.

Moderate 739 Minor 63 No known interaction 2,028 (incl. Belzutifan)
Taking anything else?

Check Another of Your Medications Against Uva Ursi

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

Everything else you take

See Every Supplement That Interacts With Belzutifan

This page covers Uva Ursi only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Belzutifan page lists 60 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Adrafinil (moderate), Artichoke (moderate), Bacopa (moderate) and Baikal Skullcap (moderate).

By severity: 1 major · 45 moderate · 14 minor.

From our pharmacist’s overview on the Belzutifan page

“A drug like belzutifan (Welireg), taken long term to keep kidney and other tumors in check, only works if a steady amount reaches the blood, so I would be genuinely careful before adding supplements here. Most of the interactions on file shift how the liver clears the drug, through the CYP2C19 enzyme or the glucuronidation pathway, nud…”

Reviewed by 2 · Jul 18, 2026

Open the Belzutifan interaction page

One more smart check

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

We hold 1,423 real supplement products containing Uva Ursi, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Uva Ursi. Your product may carry other ingredients that interact with Belzutifan too, on top of Uva Ursi — 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 Uva Ursi and Belzutifan 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 Uva Ursi
Top 25%

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

29 days ago today
Medication Belzutifan
Steady interest

#2,556 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 Uva Ursi

What is Uva Ursi?

Uva Ursi
  • Urinary tract infections
  • Urinary discomfort
  • Mild diuretic
  • Kidney stones
  • Skin conditions

Uva ursi is a traditional herb used mainly for urinary tract infections, and its leaves contain a compound called arbutin that may have antimicrobial effects in the urine. Evidence in people is limited, and because high doses or long-term use may be harmful to the liver and could be toxic, it should only be used short-term and with guidance from a healthcare professional. Avoid it during pregnancy and breastfeeding.

Read the full Uva Ursi monograph & all interactions
Medication

About Belzutifan

What Is Belzutifan Used For?

Brand name: Welireg

Welireg (belzutifan) is approved for several serious conditions. In adults with von Hippel-Lindau (VHL) disease, it treats associated kidney cancer (renal cell carcinoma), brain and spine tumors called CNS hemangioblastomas, and pancreatic neuroendocrine tumors — when surgery is not immediately needed.

Welireg also treats adults with clear cell renal cell carcinoma (ccRCC): as an adjuvant treatment (after surgery to remove the kidney) in combination with pembrolizumab or pembrolizumab and berahyaluronidase alfa-pmph to reduce the risk of recurrence, and as a single agent for advanced ccRCC after certain prior therapies have been tried. Additionally, Welireg treats adults and patients aged 12 and older with locally advanced, unresectable, or metastatic pheochromocytoma or paraganglioma (PPGL) — rare tumors of the adrenal glands or nearby nerve tissue.

See full Belzutifan drug information
Keep checking

Other Drugs & Uva Ursi

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

0Major
739Moderate
63Minor
2,027No known interaction
739 Moderate 63 Minor 2,027 No interaction
Moderate

739 interactions

Showing 60 of 739 moderate interactions — see all 739 on the Uva Ursi page.

Minor

63 interactions

Showing 60 of 63 minor interactions — see all 63 on the Uva Ursi page.

No interaction 2,027 drugs checked — show the list

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

Showing the 60 most looked-up of 2,027 medications checked with no known interaction — see the full Uva Ursi list.

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

Can you take Uva Ursi with Belzutifan?
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 2 interactions listed for Uva Ursi and Belzutifan?
Belzutifan belongs to more than one drug category, and Uva Ursi 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 Uva Ursi and Belzutifan 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 Belzutifan and Uva Ursi?

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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.