Drug & supplement interaction

Quercetin + Fluoxetine

Fluoxetine brand names: Prozac, Sarafem.

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

Fluoxetine falls into 2 drug categories that Quercetin can interact with; the most serious is rated moderate. Theoretically, concomitant use might increase the levels and adverse effects of CYP2D6 substrates.

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

Quercetin and Fluoxetine

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

Why Are There 2 Interactions?

Quercetin interacts with whole categories of medication. Fluoxetine falls into 2 of those categories, so it can interact with Quercetin 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 2D6 (CYP2D6) SUBSTRATES

1 of 2

Why this applies to Fluoxetine

Fluoxetine falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Quercetin interacts with.

Theoretically, concomitant use might increase the levels and adverse effects of CYP2D6 substrates.

In vitro research show that quercetin inhibits CYP2D6. 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 with quercetin and fluoxetine (Prozac). Your liver uses an enzyme called CYP2D6 to help break fluoxetine down. In lab dish studies, quercetin appears to block that enzyme. If that same effect happened in people, fluoxetine could clear more slowly and build up a bit, which in theory might mean more of its usual side effects, things like nausea, jitteriness, trouble sleeping, headache, or dry mouth.

I want to be honest about how soft this evidence is. It comes from test tube research only and hasn't actually been seen in humans, so I wouldn't lose sleep over it. Everyday food amounts of quercetin are very unlikely to matter. Still, before starting a concentrated supplement, it's worth a quick chat with your pharmacist or doctor.

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
Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

2 of 2

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

Theoretically, concomitant use might increase the levels and adverse effects of CYP2C9 substrates.

A small clinical study in healthy volunteers shows that taking quercetin 500 mg twice daily for 10 days prior to taking diclofenac, a CYP2C9 substrate, increases diclofenac plasma levels by 75% and prolongs the half-life by 32.5%. Animal research also shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar), a substrate of CYP2C9. Furthermore, laboratory research shows that quercetin inhibits CYP2C9.
Severity Moderate Likelihood Possible Evidence B

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: high-dose quercetin can block a liver enzyme called CYP2C9, which is one of the routes your body uses to clear fluoxetine (Prozac). If that pathway slows down, a little more fluoxetine can linger in your system. Fluoxetine isn't a prodrug, so this would mean slightly stronger effects, not weaker ones. In real life that could show up as more nausea, jitteriness, trouble sleeping, or headache.

I want to keep this in perspective, though. The evidence is mostly theoretical and based on other drugs, not fluoxetine itself, and the supplement amounts in everyday foods are very unlikely to matter. It's the concentrated capsules that warrant a quick chat with your pharmacist or doctor before starting.

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. Bedada SK, Neerati P. Evaluation of the effect of quercetin treatment on CYP2C9 enzyme activity of diclofenac in healthy human volunteers. Phytother Res. 2018 Feb;32(2):305-311. doi: 10.1002/ptr.5978. PubMed
  4. 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

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 Fluoxetine one above is among them. If you take anything else, check it against the full list below.

Moderate 1,168 No known interaction 1,662 (incl. Fluoxetine)
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.

From our Q&A

Questions About Quercetin or Fluoxetine

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

This page covers Quercetin only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fluoxetine page lists 163 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 8 major · 127 moderate · 28 minor.

From our pharmacist’s overview on the Fluoxetine page

“Grapefruit is the surprise at the top of fluoxetine's (Prozac) supplement list. In large amounts it can stretch the QT interval, the electrical pause between heartbeats, and fluoxetine, a widely prescribed antidepressant, can do the same, raising the odds of a dangerous rhythm.”

Reviewed by 2 · Jul 18, 2026

Open the Fluoxetine 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 Fluoxetine 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 Fluoxetine 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 Fluoxetine
Top 1%

#27 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 Fluoxetine

What Is Fluoxetine Used For?

Brand names: Prozac, Sarafem

Fluoxetine is approved to treat four conditions: major depressive disorder (MDD), obsessive-compulsive disorder (OCD), bulimia nervosa (a binge-eating and purging disorder), and panic disorder — with or without agoraphobia (fear of situations that feel hard to escape).

It works for adults across all four conditions, and for children and teens with depression (ages 8–18) and OCD (ages 7–17).

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

Can you take Quercetin with Fluoxetine?
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 Quercetin and Fluoxetine?
Fluoxetine belongs to more than one drug category, and Quercetin 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 Quercetin and Fluoxetine 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 Fluoxetine 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.