Interactions on record — worth a quick check against your medications. Check your meds →
Dietary supplement

Quercetin Ingredients & Drug Interactions

by Natural Factors

Quercetin label
See full label image
Capsule Category: Other Combinations
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Quercetin against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Quercetin is a dietary supplement by Natural Factors with 4 active ingredients. Its ingredients are commonly taken for inflammation and swelling, sinus and nasal congestion, digestion support.Based on those ingredients, 1,212 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Quercetin Bioflavonoids extract, Bromelain, Rutin extract. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Quercetin by Natural Factors

Ask about any prescription or over-the-counter medication and we check it for interactions with Quercetin by Natural Factors — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Quercetin by Natural Factors

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Sep 10, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 4 of its 4 active ingredients.
  • “Quercetin Bioflavonoids extract” is listed as a grouped ingredient — the label gives one combined amount (235 mg) without saying how much of each component you get.

This product contains four active ingredients: bromelain (an enzyme from pineapple), quercetin bioflavonoids extract, Japanese pagoda flower, and rutin extract. The product also includes inactive ingredients (gelatin capsule, rice powder, magnesium stearate, and silica) that serve as fillers and capsule material.

Does it work?

Couldn't assess
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Not assessable

The label doesn't state a purpose we can grade — see each ingredient's own graded uses on its monograph instead.

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.

The evidence for this product's effectiveness is not well established. Bromelain, quercetin, Japanese pagoda, and rutin all show insufficient reliable evidence or are rated possibly ineffective for their commonly claimed uses—which include allergic rhinitis (hay fever), blood sugar control, and inflammation-related conditions.

The data we hold does not support a clear benefit for any specific health goal at this time.

The evidence, ingredient by ingredient Bromelain Quercetin Pagoda Tree Rutin

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 4 of the 4 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 4 of 4.
  • General safety write-ups exist for 4 of 4.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Bromelain and quercetin are generally well tolerated at typical supplement doses, though long-term safety data are limited. Bromelain may cause diarrhea, flatulence, stomach upset, and headache when taken by mouth, and can trigger allergic reactions (including asthma if inhaled) in sensitive people.

Quercetin may cause headache and tingling in the extremities. Rutin may cause headache, flushing, or rashes in some people.

Japanese pagoda flower appears generally well tolerated, but safety data are sparse; the seed is possibly unsafe long-term and has been linked to serious effects including edema and death. Pregnancy and breastfeeding safety is a concern: bromelain should be avoided during pregnancy and breastfeeding (not enough data).

Quercetin should be avoided at supplement doses during pregnancy and breastfeeding. Rutin is likely safe during pregnancy, but safety while breastfeeding is unknown, so avoid supplement doses unless your doctor advises otherwise.

Japanese pagoda is possibly unsafe in pregnancy and should be avoided; safety while breastfeeding is unknown. Talk with your doctor or pharmacist if you're pregnant, planning pregnancy, or breastfeeding before taking this product.

Side effects, ingredient by ingredient Bromelain Quercetin Pagoda Tree Rutin

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 4 of the 4 matched ingredients can interact with medications — Pagoda Tree, Rutin, Quercetin, Bromelain.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; immunosuppressants / transplant drugs; diabetes medications.
  • For scale: 1,213 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before taking this product, check with your doctor or pharmacist if you take blood thinners or antiplatelet drugs (warfarin, aspirin, clopidogrel)—quercetin and bromelain may increase bleeding risk. Also double-check if you use statins (especially pravastatin), the blood-pressure drug losartan, the immune suppressant cyclosporine, sulfasalazine, quinolone antibiotics, diabetes medications, or high amounts of caffeine, as this product may change how they work or their levels in your blood.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no assessable stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

Natural Factors Quercetin is a multi-ingredient supplement with significant interaction potential, especially if you take blood thinners, statins, blood-pressure medications, antibiotics, diabetes drugs, or caffeine regularly. The effectiveness evidence for its claimed uses is not established in the data we hold.

Before you start this product, check your medications and any supplements with your doctor or pharmacist—the interaction list is lengthy and the safety in pregnancy and breastfeeding is limited.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 4 of 4 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jul 25, 2017.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Quercetin, straight from the product label.

Brand Natural Factors
Barcode (UPC) 068958013879
Net contents 90 Capsule(s)
Market status On market
Date entered into DSLD Jul 25, 2017
DSLD ID 75019
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten Free, Dairy Free, Sugar Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Quercetin by Natural Factors, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Capsule(s)
Maximum serving Sizes:
1 Capsule(s)
UPC/BARCODE
068958013879
IngredientAmount% DV
Bromelain45 mg--
Quercetin Bioflavonoids extract235 mg--
Japanese Pagoda4.7 Gram(s)--
Citrus Bioflavonoids extract235 mg--
Rutin extract45 mg--

Other ingredients: Gelatin Capsule, Rice powder, Magnesium Stearate, Silica

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Brand IP Statement(s)

Isura

Formulation

Non-GMO

Contains no artificial colors, preservatives or sweeteners; no dairy, sugar, wheat, gluten, yeast, soy, corn, egg, fish, shellfish, salt, tree nuts, or GMOs.

General Statements

Mass spec Documentation Lab tested

Manufactured by Natural Factors to ensure safety and potency in accordance with Good Manufacturing Practices (GMP) of the FDA and Health Canada.

Product of Canada Recyclable container and label.

Bioflavonoid complex

Healthy immune support

Quercetin, a popular bioflavonoid, is essential to optimize the body's use of vitamin C. Bioflavonoids are brightly-colored substances that are found in fruit and vegetables, typically as companions to vitamin C. Bioflavonoids are essential for proper absorption of vitamin C and have been shown to have antioxidant properties, increase capillary strength and keep collagen healthy.

Suggested/Recommended/Usage/Directions

Suggested Usage: 1 capsule 1-3 times per day or as directed by a health professional.

Precautions

Cautions: As with any supplement, consult your health professional before use if you are pregnant, breastfeeding, or trying to conceive, or if you are taking medication, have a medical condition, or anticipate a surgery.

Keep out of the reach of children.

Sealed for your protection. Do not use if seal is broken.

Storage

For freshness, store in a cool, dry place.

FDA Disclaimer Statement

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

Seals/Symbols

Purity & potency guaranteed

FDA Statement of Identity

Dietary Supplement

General

R5

Formula

Quercetin capsules are enhanced with citrus bioflavonoids, bromelain and rutin.

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Quercetin by Natural Factors label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Quercetin label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Quercetin by Natural Factors

These are the 4 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Capsule(s) Dosage formCapsule Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Bromelain

Interacts with
141 drugs
45 mg per serving Form: Pineapple

Bromelain is a group of protein-digesting enzymes from pineapple that people take mainly for inflammation, swelling, and sinus problems. Some early st...

Bromelain monograph & interactions

Quercetin Bioflavonoids extract

Interacts with
1,169 drugs
235 mg per serving

Quercetin is a plant flavonoid with antioxidant and anti-inflammatory properties found in many common foods and sold as a supplement. While early rese...

Quercetin Bioflavonoids extract monograph & interactions

Citrus Bioflavonoids extract

Interacts with
1,169 drugs
235 mg per serving Form: Citrus Fruits

Quercetin is a plant flavonoid with antioxidant and anti-inflammatory properties found in many common foods and sold as a supplement. While early rese...

Citrus Bioflavonoids extract monograph & interactions

Rutin extract

Interacts with
86 drugs
45 mg per serving

Rutin is a plant flavonoid (often taken from buckwheat or citrus) that people use mainly for blood vessel and circulation problems like varicose veins...

Rutin extract monograph & interactions

Other (inactive) ingredients: Gelatin Capsule, Rice powder, Magnesium Stearate, Silica. These complete the product’s ingredient list but are not active constituents.

Interaction report

Quercetin by Natural Factors Drug Interactions

Want to check YOUR meds against Quercetin?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
1,212Drugs
1,208 Moderate 4 Minor

Ingredients driving the most interactions

Quercetin Bioflavonoids extract 1,169
Bromelain 141
Rutin extract 86

Individual Drug Interactions

The ingredients in Quercetin interact with 1,212 drugs. Click any drug to see the details.

3 of the 4 ingredients in Quercetin interact with drugs. Each result below shows which ingredient is responsible. Quercetin Bioflavonoids extract Bromelain Rutin extract

Each ingredient & the kinds of drugs it affects

For each ingredient in Quercetin with known interactions, here are the types of medications they can affect. Open any type for the detail — or search your exact drug in the checker above.

Quercetin Bioflavonoids extract21 drug types · 1,169 drugs

Antidiabetes Drugs

Theoretically, concomitant use of quercetin and antidiabetes drugs might increase the risk of hypoglycemia.

Clinical research suggests that a combination of quercetin, myricetin, and chlorogenic acid reduce levels of fasting glucose in patients with type 2 diabetes, including those already taking antidiabetes agents. The effect of quercetin alone is unknown.

Likelihood Possible Evidence B
Antihypertensive Drugs

Theoretically, taking quercetin with antihypertensive drugs might increase the risk of hypotension.

Quercetin can modestly decrease blood pressure in people with mild hypertension. Theoretically, it might have additive blood pressure lowering effects when used with antihypertensive drugs.

Likelihood Possible Evidence B
Cyclosporine (Neoral, Sandimmune)

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

A small study in healthy volunteers shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of a single dose of cyclosporine, possibly due to inhibition of p-glycoprotein or cytochrome P450 3A4 (CYP3A4), which metabolizes cyclosporin.

Likelihood Possible Evidence B
Cytochrome P450 2C8 (Cyp2C8) Substrates

Theoretically, concomitant use might increase the levels and adverse effects of CYP2C8 substrates.

In vitro research shows that quercetin inhibits CYP2C8. Inhibition of paclitaxel (Taxol) metabolism via CYP2C8 has been reported in vitro. However, a small study in humans found no effect of quercetin on rosiglitazone (Avandia), which is also a CYP2C8 substrate.

Likelihood Possible Evidence D
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.

Likelihood Possible Evidence B
Cytochrome P450 2D6 (Cyp2D6) Substrates

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.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

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.

Likelihood Possible Evidence D
Diclofenac (Voltaren, Others)

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

A small clinical study in healthy volunteers shows that taking quercetin 500 mg twice daily for 10 days prior to taking diclofenac increases diclofenac plasma levels by 75% and prolongs the half-life by 32.5%. This is thought to be due to inhibition of CYP2C9 by quercetin.

Likelihood Probable Evidence B
Losartan (Cozaar)

Theoretically, concomitant use might increase the effects and adverse effects of losartan and decrease the effects of its active metabolite.

Animal research shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar) while decreasing plasma levels of losartan's active metabolite. This metabolite, which is around 10-fold more potent than losartan, is the result of cytochrome P450 (CYP) 2C9- and CYP3A4-mediated transformation of losartan. Additionally, in vitro research shows that quercetin may inhibit P-glycoprotein-mediated efflux of losartan from the intestines, resulting in increased absorption of losartan. These results suggest that concomitant use of quercetin and losartan might increase systemic exposure to losartan while also decreasing plasma concentrations of losartan's active and more potent metabolite.

Likelihood Possible Evidence D
Midazolam (Versed)

Theoretically, concomitant use might decrease the levels and effects of midazolam.

A small clinical study in healthy volunteers shows that quercetin can increase the metabolism of midazolam, with a decrease in AUC of about 24%.

Likelihood Possible Evidence B
Mitoxantrone

Theoretically, quercetin might increase the effects and adverse effects of mitoxantrone.
In vitro research shows that quercetin increases the intracellular accumulation and cytotoxicity of mitoxantrone, possibly through inhibition of breast cancer resistance protein (BCRP), of which mitoxantrone is a substrate. So far, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Organic Anion Transporter 1 (Oat1) Substrates

Theoretically, concomitant use might increase the effects and adverse effects of OAT1 substrates.

In vitro research shows that quercetin is a strong non-competitive inhibitor of OAT1, with half-maximal inhibitory concentration (IC50) values less than 10 mcM. So far, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Organic Anion Transporter 3 (Oat3) Substrates

Theoretically, concomitant use might increase the effects and adverse effects of OAT3 substrates.

In vitro research shows that quercetin is a strong non-competitive inhibitor of OAT3, with half-maximal inhibitory concentration (IC50) values as low as 0.75 mcM. So far, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Organic Anion-Transporting Polypeptide Substrates (Oatp)

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

In vitro evidence shows that quercetin can inhibit organic anion-transporting peptide (OATP) 1B1-mediated uptake of estrone-3-sulfate and pravastatin. Furthermore, clinical research in healthy males shows that intake of quercetin along with pravastatin increases the AUC of pravastatin by 24%, prolongs its half-life by 14%, and decreases its apparent clearance by 18%, suggesting that quercetin modestly inhibits the uptake of pravastatin in hepatic cells.

Likelihood Possible Evidence B
P-Glycoprotein Substrates

Theoretically, concomitant use might alter the effects and adverse effects of P-glycoprotein substrates.

There is preliminary evidence that quercetin inhibits the gastrointestinal P-glycoprotein efflux pump, which might increase the bioavailability and serum levels of drugs transported by the pump. A small study in healthy volunteers reported that pretreatment with quercetin increased bioavailability and plasma levels after a single dose of cyclosporine (Neoral, Sandimmune). Also, two small studies have shown that quercetin might decrease the absorption of talinolol, a substrate transported by the gastrointestinal P-glycoprotein efflux pump. However, in another small study, several days of quercetin treatment did not significantly affect the pharmacokinetics of saquinavir (Invirase). The reason for these discrepancies is not entirely clear. Until more is known, use quercetin cautiously in combination with P-glycoprotein substrates.

Likelihood Possible Evidence B
Pravastatin (Pravachol)

Theoretically, concomitant use might increase the effects and adverse effects of pravastatin.
In vitro evidence shows that quercetin can inhibit OATP 1B1-mediated uptake of pravastatin. Also, preliminary clinical research in healthy males shows that intake of quercetin along with pravastatin increases the maximum concentration of pravastatin by 24%, prolongs its half-life by 14%, and decreases its apparent clearance by 18%, suggesting that quercetin modestly inhibits the uptake of pravastatin in hepatic cells.

Likelihood Possible Evidence B
Prazosin (Minipress)

Theoretically, quercetin might increase the effects and adverse effects of prazosin.
In vitro research shows that quercetin inhibits the transcellular efflux of prazosin, possibly through inhibition of breast cancer resistance protein (BCRP), of which prazosin is a substrate. BCRP is an ATP-binding cassette efflux transporter in the intestines, kidneys, and liver. So far, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Quetiapine (Seroquel)

Theoretically, concomitant use might increase the effects and adverse effects of quetiapine.
Animal research shows that pretreatment with quercetin can increase plasma levels of quetiapine and prolong its clearance, possibly due to inhibition of cytochrome P450 3A4 (CYP3A4) by quercetin. Additionally, the brain-to-plasma ratio of quetiapine concentrations increased, possibly due to inhibition of P-glycoprotein at the blood-brain barrier. This interaction has not been reported in humans.

Likelihood Possible Evidence D
Quinolone Antibiotics

Theoretically, concomitant use might inhibit the effects of quinolone antibiotics.
In vitro, quercetin binds to the DNA gyrase site on bacteria, which may interfere with the activity of quinolone antibiotics.

Likelihood Possible Evidence B
Sulfasalazine (Azulfidine)

Theoretically, quercetin might increase the effects and adverse effects of sulfasalazine.
Animal research shows that quercetin increases the maximum serum concentration (Cmax) and area under the curve (AUC) of sulfasalazine, possibly through inhibition of breast cancer resistance protein (BCRP), of which sulfasalazine is a substrate. So far, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, quercetin may increase the risk of bleeding if used with warfarin.
Animal and in vitro studies show that quercetin might increase serum levels of warfarin. Quercetin and warfarin have the same human serum albumin (HSA) binding site, and in vitro research shows that quercetin has stronger affinity for the HSA binding site and can theoretically displace warfarin, causing higher serum levels of warfarin. Animal research shows that taking quercetin for 2 weeks before initiating warfarin increases the maximum serum level of warfarin by 30%, the half-life by 10%, and the overall exposure by 63% when compared with control. Concomitant administration of quercetin and warfarin, without quercetin pre-treatment, also increased these measures, but to a lesser degree. Researchers theorize that inhibition of CYP3A4 by quercetin may explain these effects. So far, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Quercetin Bioflavonoids extract full monograph & interactions

Bromelain2 drug types · 141 drugs

Anticoagulant/Antiplatelet Drugs

Bromelain may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
There is one case report of a patient experiencing minor bruising while taking bromelain with naproxen. Bromelain is thought to have antiplatelet activity. Whether this interaction is of concern with topical bromelain is unclear. Interference with coagulation of burn wounds has been reported in a patient receiving bromelain-based enzymatic debridement. However, observational research has found that topical bromelain debridement is not associated with increases or decreases in laboratory markers of coagulation when compared with surgical debridement.

Likelihood Possible Evidence D
Tetracycline Antibiotics

Theoretically, bromelain might increase levels of tetracycline antibiotics.
Laboratory research suggests that bromelain might increase the absorption of tetracycline antibiotics. However, a study in healthy adults reported no difference in tetracycline plasma levels when a 500 mg dose was taken with or without bromelain 80 mg.

Likelihood Possible Evidence B
Bromelain full monograph & interactions

Rutin extract1 drug type · 86 drugs

Antidiabetes Drugs

Theoretically, taking rutin with antidiabetes drugs might increase the risk of hypoglycemia.
Animal research suggests that rutin has hypoglycemic effects.

Likelihood Possible Evidence D
Rutin extract full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Quercetin, from the product label.

Natural Factors

See all Natural Factors products
Name
Natural Factors Canada
Pharmacist Counseling Corner

Quercetin by Natural Factors: Common Questions

Does Quercetin by Natural Factors interact with any medications?
Yes. Based on its ingredients, Quercetin has a known interaction with 1,212 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Quercetin contains 4 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
What is bromelain and why is it in this product?
Bromelain is an enzyme derived from pineapple. It's included in supplements for its potential anti-inflammatory and other effects, though evidence for most uses is limited.
Can I take this if I'm pregnant or breastfeeding?
No, you should avoid this product during pregnancy and breastfeeding. Bromelain and quercetin lack enough safety data in pregnancy; rutin is likely safe in pregnancy but its safety while breastfeeding is unknown; and Japanese pagoda is possibly unsafe during pregnancy. Talk with your doctor or pharmacist for advice tailored to your situation.
What side effects might I experience?
The most common are digestive: diarrhea, flatulence, stomach upset, and nausea. You may also experience headache, tingling in the extremities, flushing, or rashes. If you have a pineapple allergy, bromelain may trigger an allergic reaction.
Is there evidence this supplement actually works?
The evidence for this product's claimed uses—such as allergies, inflammation, or blood sugar control—is not well established. Each ingredient is rated as having insufficient reliable evidence or being possibly ineffective for its common uses.
Does this product contain any fillers?
Yes. Beyond the four active ingredients, it contains gelatin capsule, rice powder, magnesium stearate, and silica as inactive ingredients.
I'm on diabetes medication—is this safe?
Not without checking first. Rutin in this product may increase the risk of low blood sugar (hypoglycemia) when combined with diabetes drugs. Talk with your doctor or pharmacist before taking it.

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

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Quercetin label
Go deeper

The Full Monographs Behind Quercetin’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Bromelain

Interacts with 141 drugs

Bromelain is a group of protein-digesting enzymes from pineapple that people take mainly for inflammation, swelling, and sinus problems. Some early studies are promising, but the overall evi...

Read the full Bromelain monograph → Herb & supplement monograph

Quercetin

Interacts with 1,169 drugs

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...

Read the full Quercetin monograph → Herb & supplement monograph

Pagoda Tree

Interacts with 29 drugs

Pagoda Tree (Styphnolobium japonicum, also called the Japanese pagoda tree) is a traditional Asian medicinal plant best known as a natural source of the flavonoid rutin. While it has a long...

Read the full Pagoda Tree monograph → Herb & supplement monograph

Rutin

Interacts with 86 drugs

Rutin is a plant flavonoid (often taken from buckwheat or citrus) that people use mainly for blood vessel and circulation problems like varicose veins and hemorrhoids. The evidence is limite...

Read the full Rutin monograph →
Sources

Sources & How We Checked

Quercetin's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 49 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Bromelain 19 references
  1. Nettis E, Napoli G, Ferrannini A, Tursi A. IgE-mediated allergy to bromelain. Allergy 2001;56:257-8. PubMed
  2. Taussig SJ, Batkin S. Bromelain, the enzyme complex of pineapple (Ananas comosus) and its clinical application. An update. J Ethnopharmacol 1988;22:191-203.. PubMed
  3. Bradbrook ID, Morrison PJ, Rogers HJ. The effect of bromelain on the absorption of orally administered tetracycline. Br J Clin Pharmacol 1978;6:552-4. PubMed
  4. Bush TM, Rayburn KS, Holloway SW, et al. Adverse interactions between herbal and dietary substances and prescription medications: a clinical survey. Altern Ther Health Med 2007;13:30-5.
  5. Brien S, Lewith G, Walker AF, et al. Bromelain as an adjunctive treatment for moderate-to-severe osteoarthritis of the knee: a randomized placebo-controlled pilot study. QJM 2006;99:841-50. PubMed
  6. Mori S, Ojima Y, Hirose T, et al. The clinical effect of proteolytic enzyme containing bromelain and trypsin on urinary tract infection evaluated by double blind method. Acta Obstet Gynaecol Jpn 1972;19:147-53.
  7. Glaser D, Hilberg T. The influence of bromelain on platelet count and platelet activity in vitro. Platelets 2006;17:37-41. PubMed
  8. Heinicke R M, van der Wal L, Yokoyama M. Effect of bromelain (Ananase) on human platelet aggregation. Experientia 1972;28:844-5. PubMed
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Quercetin 26 references
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See these in context on the Quercetin monograph →

Pagoda Tree 2 references
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See these in context on the Pagoda Tree monograph →

Rutin 2 references
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See these in context on the Rutin monograph →

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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.

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