Drug & supplement interaction

Quercetin + Enfortumab Vedotin-Ejfv

Enfortumab Vedotin-Ejfv brand name: Padcev.

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

Quercetin has a moderate interaction with Enfortumab Vedotin-Ejfv. Theoretically, concomitant use might alter the effects and adverse effects of CYP3A4 substrates.

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

Quercetin and Enfortumab Vedotin-Ejfv

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Enfortumab Vedotin-Ejfv

Enfortumab Vedotin-Ejfv falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Quercetin interacts with.

Theoretically, concomitant use might alter the effects and adverse effects of CYP3A4 substrates.
A small clinical study in healthy volunteers shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of a single dose of cyclosporine (Neoral, Sandimmune), a substrate of CYP3A4. Animal research also shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar) and quetiapine (Seroquel), substrates of CYP3A4. Other laboratory research also shows that quercetin inhibits CYP3A4. However, one clinical study shows that quercetin can increase the metabolism of midazolam, a substrate of CYP3A4, and decrease serum concentrations of midazolam by about 24% in some healthy individuals, suggesting possible induction of 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

Here's the honest picture with Padcev (enfortumab vedotin) and quercetin. Padcev is an antibody-drug conjugate, and the cancer-killing piece it carries (a chemo called MMAE) is partly handled by the liver enzyme CYP3A4. Quercetin can nudge that enzyme, mostly slowing it down in lab and animal studies. If it slows the breakdown of that toxic payload, more could linger in your body, which in theory might bump up Padcev's side effects like numbness or tingling in the hands and feet, skin rashes, high blood sugar, fatigue, or nausea.

I want to be straight with you: this is theoretical, drawn from test-tube and animal work, and the human data even points both directions. Food amounts of quercetin almost certainly don't matter. Still, with a serious cancer drug like this, please clear any high-dose supplement with your oncology team first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Obach RS. Inhibition of human cytochrome P450 enzymes by constituents of St. John's wort, an herbal preparation used in the treatment of depression. J Pharmacol Exp Ther 2000;294:88-95. DOI
  2. DiCenzo R, Frerichs V, Larppanichpoonphol P, et al. Effect of quercetin on the plasma and intracellular concentrations of saquinavir in healthy adults. Pharmacotherapy 2006;26:1255-61. PubMed
  3. Choi JS, Choi BC, Choi KE. Effect of quercetin on the pharmacokinetics of oral cyclosporine. Am J Health Syst Pharm 2004;61:2406-9. PubMed
  4. Choi JS, Jo BW, Kim YC. Enhanced paclitaxel bioavailability after oral administration of paclitaxel or prodrug to rats pretreated with quercetin. Eur J Pharm Biopharm 2004;57:313-8. PubMed
  5. Duan KM, Wang SY, Ouyang W, Mao YM, Yang LJ. Effect of quercetin on CYP3A activity in Chinese healthy participants. J Clin Pharmacol 2012;52(6):940-6. PubMed
  6. Zhao Q, Wei J, Zhang H. Effects of quercetin on the pharmacokinetics of losartan and its metabolite EXP3174 in rats. Xenobiotica 2019;49(5):563-8. PubMed
  7. Bhutani P, Rajanna PK, Paul AT. Impact of quercetin on pharmacokinetics of quetiapine: insights from in-vivo studies in wistar rats. Xenobiotica. 2020:1-7.

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

Quercetin Also Interacts With Other Medications

Quercetin has 1,168 moderate known drug interactions in our database — the Enfortumab Vedotin-Ejfv one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,168 No known interaction 1,662 (incl. Enfortumab Vedotin-Ejfv)
Taking anything else?

Check Another of Your Medications Against Quercetin

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

Everything else you take

See Every Supplement That Interacts With Enfortumab Vedotin-Ejfv

This page covers Quercetin only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Enfortumab Vedotin-Ejfv page lists 121 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 2 major · 87 moderate · 32 minor.

From our pharmacist’s overview on the Enfortumab Vedotin-Ejfv page

“If you are getting Padcev (enfortumab vedotin) infusions for bladder cancer, treat this page as one worth genuine attention. The chemotherapy payload in Padcev is cleared by a liver enzyme called CYP3A4, and all 121 ingredients listed here act on that enzyme, either blocking it so the drug builds up or speeding it up so treatment weakens.”

Reviewed by 2 · Jul 18, 2026

Open the Enfortumab Vedotin-Ejfv interaction page

One more smart check

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

We hold 4,589 real supplement products containing Quercetin, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Quercetin. Your product may carry other ingredients that interact with Enfortumab Vedotin-Ejfv too, on top of Quercetin — 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 Quercetin and Enfortumab Vedotin-Ejfv 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 Quercetin
Top 5%

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

29 days ago today
Medication Enfortumab Vedotin-Ejfv
Top 25%

#398 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 Quercetin

What is Quercetin?

Quercetin
  • Seasonal allergies
  • Antioxidant support
  • Heart and blood pressure health
  • Anti-inflammatory support
  • Immune support
  • Exercise recovery

Quercetin is a plant flavonoid with antioxidant and anti-inflammatory properties found in many common foods and sold as a supplement. While early research is interesting for allergies, blood pressure, and inflammation, strong human evidence is limited for most uses. It is generally well tolerated in food amounts, but talk to your pharmacist or doctor before taking high-dose supplements.

Read the full Quercetin monograph & all interactions
Medication

About Enfortumab vedotin-ejfv Injection

What Is Enfortumab vedotin-ejfv Injection Used For?

Brand name: Padcev

  • Enfortumab vedotin-ejfv injection is used to treat urothelial cancer (cancer of the lining of the bladder and other parts of the urinary tract) that has spread to nearby tissues or other parts of the body or cannot be removed by surgery, and has worsened after treatment with other chemotherapy medications or if these chemotherapy medications cannot be used for treatment. Enfortumab vedotin-ejfv injection is in a class of medications called monoclonal antibodies. It works by helping your immune system to slow or stop the growth of cancer cells.

See full Enfortumab vedotin-ejfv Injection drug information
Keep checking

Other Drugs & Quercetin

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

0Major
1,168Moderate
0Minor
1,661No known interaction
1,168 Moderate 1,661 No interaction
Moderate

1,168 interactions

Showing 60 of 1,168 moderate interactions — see all 1,168 on the Quercetin page.

No interaction 1,661 drugs checked — show the list

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

Showing the 60 most looked-up of 1,661 medications checked with no known interaction — see the full Quercetin list.

See the full Quercetin interactions page
See every supplement checked against Enfortumab Vedotin-Ejfv, 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
Quercetin monograph › Uses, safety, and every drug interaction in one place Enfortumab Vedotin-Ejfv supplement interactions › Every supplement checked against Enfortumab Vedotin-Ejfv, ranked by severity Enfortumab vedotin-ejfv Injection 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 Quercetin and Enfortumab Vedotin-Ejfv Together: Common Questions

Can you take Quercetin with Enfortumab Vedotin-Ejfv?
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 Quercetin and Enfortumab Vedotin-Ejfv 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 Enfortumab Vedotin-Ejfv and Quercetin?

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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.