Major interaction on record — check this product against your medications before combining. Based on 3 of 4 ingredients. Check your meds →
Dietary supplement

Quercetin 20x Plus Ingredients & Drug Interactions

by XYMOGEN

Quercetin 20x Plus label
See full label image
Capsule Category: Other Combinations
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Quercetin 20x Plus 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: Major

Quercetin 20x Plus is a dietary supplement by XYMOGEN with 4 active ingredients. Its ingredients are commonly taken for common cold and immune support, antioxidant support, skin health and collagen formation.Based on those ingredients, 553 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are N-Acetyl-L-Cysteine, Vitamin C, Nettle Leaf 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 20x Plus by XYMOGEN

Ask about any prescription or over-the-counter medication and we check it for interactions with Quercetin 20x Plus by XYMOGEN — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Quercetin 20x Plus by XYMOGEN

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 Jul 11, 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.
  • No proprietary blends here — you can verify the dose of every single component.

Quercetin 20x Plus contains 4 active ingredients. Vitamin C supports immune function and acts as an antioxidant.

N-acetyl-L-cysteine (NAC) is an amino acid that helps your body produce glutathione, a natural detoxifier. Nettle Leaf Extract comes from the stinging nettle plant.

Quercefit is a proprietary blend we have no detailed data on. The capsule also contains inactive ingredients—hypromellose (the capsule material itself), water, ascorbyl palmitate, and silica—which are fillers and binders that help the product hold together.

Does it work?

Strong evidence
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
Strong

Clinical evidence supports at least one of this product's ingredients for its stated purpose.

Why this rating?
  • The label markets this product for: support respiratory system including nasal passages.
  • We looked for evidence on: Acute bronchitis, Allergic rhinitis (hay fever), Asthma, Atelectasis, Bronchiectasis, Bronchitis — and 4 related terms.
  • The strongest evidence on file: N-acetyl Cysteine (nac) is rated "Effective" for Atelectasis (Natural Medicines).
  • Also on file: N-acetyl Cysteine (nac) is rated "Possibly Effective" for Bronchitis.
  • Also on file: Vitamin C is rated "Possibly Ineffective" for Acute bronchitis.

In our data, vitamin C is effective for vitamin C deficiency and possibly effective for anemia of chronic disease, atrial fibrillation, cataracts, and exercise-induced respiratory infections. N-acetyl-L-cysteine is effective for acetaminophen (Tylenol) poisoning, atelectasis (lung collapse), and bronchial diagnostic studies, and possibly effective for bronchitis.

Nettle leaf extract is possibly effective for diabetes and has insufficient evidence for allergic rhinitis, anemia, asthma, benign prostatic hyperplasia, and gingivitis. We hold no effectiveness data for Quercefit.

The evidence, ingredient by ingredient Vitamin C N-acetyl Cysteine (nac) Stinging Nettle

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 3 of the 3 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 3 of 3.
  • General safety write-ups exist for 3 of 3.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Vitamin C is generally well tolerated at normal supplement doses but can cause abdominal cramps, heartburn, diarrhea, nausea, and headache—especially above 2 grams daily. Kidney stones have been reported in people prone to them.

High doses taken during pregnancy are not advised; normal amounts from food and prenatal vitamins are safe. N-acetyl-L-cysteine is generally well tolerated at typical doses but most commonly causes diarrhea, dry mouth, nausea, and vomiting; we hold no pregnancy safety data for it.

Nettle leaf extract is generally well tolerated but may cause constipation or diarrhea; the safety data advises against it in pregnancy, and breastfeeding safety has not been established.

Side effects, ingredient by ingredient Vitamin C N-acetyl Cysteine (nac) Stinging Nettle

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 3 of the 3 matched ingredients can interact with medications — Stinging Nettle, Vitamin C, N-acetyl Cysteine (nac).
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; cancer treatments; diabetes medications; lithium.
  • For scale: 553 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 you take Quercetin 20x Plus, double-check these medication types with your pharmacist, worst first: nitroglycerin (Major severity risk), then blood thinners like warfarin, estrogen-containing birth control or hormone therapy, blood pressure medications, blood sugar medicines, thyroid medication (levothyroxine), lithium, and certain chemotherapy drugs. If you take any of these, run them through the checker on this page.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with clinical evidence supporting its stated purpose. Major medication interactions have been identified, and safety information is well characterized.

This product is a combination of well-known antioxidants and herbal ingredients. If you take nitroglycerin, blood thinners, birth control, blood pressure medication, diabetes medication, thyroid medication, or lithium, talk to your pharmacist before starting it.

Anyone planning pregnancy or currently breastfeeding should discuss this product with their doctor first—especially the nettle leaf component.

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

Assessment coverage: 3 of 4 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jul 24, 2025.

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 20x Plus, straight from the product label.

Brand XYMOGEN
Barcode (UPC) 722537512701
Net contents 120 Vegetarian Capsule(s)
Market status On market
Date entered into DSLD Jul 24, 2025
DSLD ID 335558
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), No Allergies, Gluten Free, Dairy 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 20x Plus by XYMOGEN, 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:
2 Capsule(s)
Maximum serving Sizes:
2 Capsule(s)
Servings per container
60
UPC/BARCODE
722537512701
IngredientAmount% DV
Vitamin C200 mg222%
N-Acetyl-L-Cysteine100 mg--
Quercefit250 mg--
Nettle Leaf Extract200 mg--

Other ingredients: Hypromellose, Water, Ascorbyl Palmitate, 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.
Suggested/Recommended/Usage/Directions

Directions: Take two capsules daily, or use as directed by your healthcare professional.

Precautions

Consult your healthcare professional before use. Do not use if tamper seal is damaged.

Individuals taking medication should discuss potential interactions with their healthcare professional.

Formula

Quercetin 20x Plus is scientifically formulated to support the respiratory system, including nasal passages. It features Quercefit, a highly absorbable Quercetin formulated with Phytosome technology, combined with nettle extract and antioxidant compounds to target immune-system - related pathways connected to respiratory symptoms.

Quercefit

Quercetin Phytosome - Antioxidant Complex

FDA Disclaimer Statement

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

Storage

Storage: Keep tightly closed in a cool, dry place out of reach of children.

Storage: Keep tightly closed in a cool, dry place out of reach of children.

Formulation

Formulated to Exclude: Wheat, gluten, yeast, soy, animal and dairy products, fish, shellfish, peanuts, tree nuts, egg, sesame, ingredients derived from genetically modified organisms (GMOs), artificial colors, and artificial sweeteners.

Vegetarian caps

Brand IP Statement(s)

S1. Quercefit and Phytosome are trademarks of Indena S.p.A., Italy. Copyright 2024 XMOGEN

XYMOGEN Exclusive Professional Formulas

Seals/Symbols

ePV (ePedigree Verification)

GMP Compliant Third-Party Verified

FDA Statement of Identity

Dietary Supplement

General Statements

Scan to learn more! This package is completely recyclable

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See for yourself

Quercetin 20x Plus by XYMOGEN label

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

Quercetin 20x Plus 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 20x Plus by XYMOGEN

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

Serving size2 Capsule(s) Dosage formCapsule Servings per container60 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.

Vitamin C

Interacts with
207 drugs
200 mg per serving Form: Ascorbic Acid

Vitamin C (ascorbic acid) is an essential nutrient your body needs but cannot make, so you must get it from food or supplements. It's important for im...

Vitamin C monograph & interactions

N-Acetyl-L-Cysteine

Interacts with
294 drugs
100 mg per serving

N-acetyl cysteine (NAC) is a supplement form of the amino acid cysteine and a building block for the antioxidant glutathione. It has well-established...

N-Acetyl-L-Cysteine monograph & interactions

Quercefit

250 mg per serving Form: Quercetin Phospholipid

Nettle Leaf Extract

Interacts with
164 drugs
200 mg per serving Form: Urtica dioica Leaf Extract, Urtica urens Leaf Extract

Stinging nettle is a common plant used as food and in traditional medicine, most often for prostate symptoms, allergies, and joint pain. The evidence...

Nettle Leaf Extract monograph & interactions

Other (inactive) ingredients: Hypromellose, Water, Ascorbyl Palmitate, Silica. These complete the product’s ingredient list but are not active constituents.

Interaction report

Quercetin 20x Plus by XYMOGEN Drug Interactions

Want to check YOUR meds against Quercetin 20x Plus?

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
553Drugs
1 Major 482 Moderate 70 Minor

Ingredients driving the most interactions

N-Acetyl-L-Cysteine 294
Vitamin C 207
Nettle Leaf Extract 164

Individual Drug Interactions

The ingredients in Quercetin 20x Plus interact with 553 drugs. Click any drug to see the details.

3 of the 4 ingredients in Quercetin 20x Plus interact with drugs. Each result below shows which ingredient is responsible. N-Acetyl-L-Cysteine Vitamin C Nettle Leaf Extract

Each ingredient & the kinds of drugs it affects

For each ingredient in Quercetin 20x Plus 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.

N-Acetyl-L-Cysteine5 drug types · 294 drugs

Nitroglycerin

N-acetyl cysteine can increase the risk for hypotension and headaches when taken with intravenous or transdermal nitroglycerin.
Clinical research shows that concomitant administration of N-acetyl cysteine and intravenous or transdermal nitroglycerin can cause severe hypotension and intolerable headaches. Furthermore, in vitro research suggests that N-acetyl cysteine increases the anticoagulant activity of nitroglycerin.

Likelihood Probable Evidence B
Activated Charcoal

N-acetyl cysteine might reduce the effects of activated charcoal, while activated charcoal might reduce the absorption of N-acetyl cysteine.
N-acetyl cysteine appears to reduce the capacity of activated charcoal to adsorb acetaminophen and salicylic acid. Conversely, although clinical research suggests that although activated charcoal can reduce the absorption of N-acetyl cysteine by up to 40%, it does not seem to reduce its clinical effects. Other clinical evidence suggests that activated charcoal does not affect the absorption of N-acetyl cysteine.

Likelihood Possible Evidence D
Anticoagulant/Antiplatelet Drugs

Theoretically, N-acetyl cysteine might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
Clinical research suggests that intravenous N-acetyl cysteine decreases prothrombin time, prolongs coagulation time, decreases platelet aggregation, and increases blood loss in surgical patients. Furthermore, in vitro research suggests that N-acetyl cysteine increases the anticoagulant activity of nitroglycerin.

Likelihood Possible Evidence D
Antihypertensive Drugs

Theoretically, N-acetyl cysteine might increase the risk of hypotension when taken with antihypertensive drugs.
Animal research suggests that N-acetyl cysteine potentiates the hypotensive effects of the angiotensin-converting enzyme inhibitors (ACEIs) captopril and enalaprilat. Theoretically, combining N-acetyl cysteine with other antihypertensive drugs might increase the risk of hypotension.

Likelihood Possible Evidence D
Chloroquine (Aralen)

Theoretically, N-acetyl cysteine might interfere with the antimalarial effects of chloroquine.
Animal research suggests that N-acetyl cysteine might reduce the antimalarial effects of chloroquine by increasing cellular levels of glutathione.

Likelihood Possible Evidence D
N-Acetyl-L-Cysteine full monograph & interactions

Vitamin C13 drug types · 207 drugs

Alkylating Agents

Theoretically, antioxidant effects of vitamin C might reduce the effectiveness of alkylating agents.
The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs that generate free radicals, such as cyclophosphamide, chlorambucil, carmustine, busulfan, and thiotepa. In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells. More evidence is needed to determine what effect, if any, antioxidants such as vitamin C have on chemotherapy.

Likelihood Possible Evidence D
Aluminum

Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Research in animals and humans shows that vitamin C increases aluminum absorption, theoretically by chelating aluminum and keeping it in solution where it is available for absorption. In people with normal renal function, urinary excretion of aluminum will likely increase, making aluminum retention and toxicity unlikely. Patients with renal failure who take aluminum-containing compounds such as phosphate binders should avoid vitamin C supplements in doses above the recommended dietary allowances.

Likelihood Probable Evidence B
Antitumor Antibiotics

Theoretically, the antioxidant effects of vitamin C might reduce the effectiveness of antitumor antibiotics.
The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs which generate free radicals, such as doxorubicin. In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells. More evidence is needed to determine what effects, if any, antioxidants such as vitamin C have on chemotherapy.

Likelihood Possible Evidence D
Estrogens

Vitamin C might increase blood levels of estrogens.
Increases in plasma estrogen levels of up to 55% occur under some circumstances when vitamin C is taken concurrently with oral contraceptives or hormone replacement therapy, including topical products. It is suggested that vitamin C prevents oxidation of estrogen in the tissues, regenerates oxidized estrogen, and reduces sulfate conjugation of estrogen in the gut wall. When tissue levels of vitamin C are high, these processes are already maximized and supplemental vitamin C does not have any effect on estrogen levels. Increases in plasma estrogen levels may occur when patients who are deficient in vitamin C take supplements. Monitor these patients for estrogen-related side effects.

Likelihood Probable Evidence B
Fluphenazine (Prolixin)

Theoretically, vitamin C might decrease levels of fluphenazine.
In one patient there was a clinically significant decrease in fluphenazine levels when vitamin C (500 mg twice daily) was started. The mechanism is not known, and there is no further data to confirm this interaction.

Likelihood Possible Evidence D
Indinavir (Crixivan)

Vitamin C can modestly reduce indinavir levels.
One pharmacokinetic study shows that taking vitamin C 1 gram orally once daily along with indinavir 800 mg orally three times daily reduces the area under the concentration-time curve of indinavir by 14%. The mechanism of this interaction is unknown, but it is unlikely to be clinically significant in most patients. The effect of higher doses of vitamin C on indinavir levels is unknown.

Likelihood Probable Evidence B
Levothyroxine (Synthroid, Others)

Vitamin C can increase levothyroxine absorption.
Two clinical studies in adults with poorly controlled hypothyroidism show that swallowing levothyroxine with a glass of water containing vitamin C 500-1000 mg in solution reduces thyroid stimulating hormone (TSH) levels and increases thyroxine (T4) levels when compared with taking levothyroxine alone. This suggests that vitamin C increases the oral absorption of levothyroxine, possibly due to a reduction in pH.

Likelihood Probable Evidence B
Warfarin (Coumadin)

High-dose vitamin C might reduce the levels and effectiveness of warfarin.
Vitamin C in high doses may cause diarrhea and possibly reduce warfarin absorption. There are reports of two people who took up to 16 grams daily of vitamin C and had a reduction in prothrombin time. Lower doses of 5-10 grams daily can also reduce warfarin absorption. In many cases, this does not seem to be clinically significant. However, a case of warfarin resistance has been reported for a patient who took vitamin C 500 mg twice daily. Cessation of vitamin C supplementation resulted in a rapid increase in international normalized ratio (INR). Tell patients taking warfarin to avoid taking vitamin C in excessively high doses (greater than 10 grams daily). Lower doses may be safe, but the anticoagulation activity of warfarin should be monitored. Patients who are stabilized on warfarin while taking vitamin C should avoid adjusting vitamin C dosage to prevent the possibility of warfarin resistance.

Likelihood Possible Evidence D
Acetaminophen (Tylenol, Others)

High-dose vitamin C might slightly prolong the clearance of acetaminophen.
A small pharmacokinetic study in healthy volunteers shows that taking high-dose vitamin C (3 grams) 1.5 hours after taking acetaminophen 1 gram slightly increases the apparent half-life of acetaminophen from around 2.3 hours to 3.1 hours. Ascorbic acid competitively inhibits sulfate conjugation of acetaminophen. However, to compensate, elimination of acetaminophen glucuronide and unconjugated acetaminophen increases. This effect is not likely to be clinically significant.

Likelihood Probable Evidence B
Aspirin

Acidification of the urine by vitamin C might increase aspirin levels.
It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels. However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion, suggesting this interaction is not clinically significant.

Likelihood Possible Evidence B
Choline Magnesium Trisalicylate (Trilisate)

Acidification of the urine by vitamin C might increase choline magnesium trisalicylate levels.
It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels. However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion, suggesting this interaction probably is not clinically significant.

Likelihood Possible Evidence B
Niacin

Vitamin C might decrease the beneficial effects of niacin on high-density lipoprotein (HDL) cholesterol levels.
A combination of niacin and simvastatin (Zocor) effectively raises HDL cholesterol levels in patients with coronary disease and low HDL levels. Clinical research shows that taking a combination of antioxidants (vitamin C, vitamin E, beta-carotene, and selenium) along with niacin and simvastatin (Zocor) attenuates this rise in HDL, specifically the HDL-2 and apolipoprotein A1 fractions, by more than 50% in patients with coronary disease. It is not known whether this adverse effect is due to a single antioxidant such as vitamin C, or to the combination. It also is not known whether it will occur in other patient populations.

Likelihood Possible Evidence A
Salsalate (Disalcid)

Acidification of the urine by vitamin C might increase salsalate levels.
It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels. However, short-term use of up to 6 grams/day vitamin C does not seem to affect urinary pH or salicylate excretion, suggesting this interaction probably is not clinically significant.

Likelihood Possible Evidence B
Vitamin C full monograph & interactions

Nettle Leaf Extract4 drug types · 164 drugs

Antidiabetes Drugs

Theoretically, stinging nettle might have additive effects with antidiabetes drugs.
Clinical research shows that stinging nettle might decrease blood glucose levels in patients with diabetes.

Likelihood Possible Evidence B
Diuretic Drugs

Theoretically, combining stinging nettle with diuretic drugs may have additive effects.
Animal research suggests that the above ground parts and roots of stinging nettle may have a diuretic effect.

Likelihood Possible Evidence D
Lithium

Theoretically, stinging nettle might reduce excretion and increase levels of lithium.
Animal research suggests that stinging nettle has diuretic and natriuretic properties, which could alter the excretion of lithium. The dose of lithium might need to be decreased.

Likelihood Possible Evidence D
Warfarin (Coumadin)

There is some concern that stinging nettle might decrease the effects of anticoagulant drugs such as warfarin.
Stinging nettle contains a significant amount of vitamin K. When taken in large quantities, this might interfere with the activity of warfarin.

Likelihood Possible Evidence D
Nettle Leaf Extract full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Quercetin 20x Plus, from the product label.

XYMOGEN

See all XYMOGEN products
Name
XYMOGEN Exclusive Professional Formulas
Street Address
6900 Kingspointe Pkwy.
City
Orlando
State
FL
ZipCode
32819
Phone Number
800-647-6100
Web Address
www.xymogen.com
Pharmacist Counseling Corner

Quercetin 20x Plus by XYMOGEN: Common Questions

Does Quercetin 20x Plus by XYMOGEN interact with any medications?
Yes. Based on its ingredients, Quercetin 20x Plus has a known interaction with 553 medications, including 1 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Quercetin 20x Plus 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.
Can I take this if I'm on birth control?
Vitamin C in this product may increase estrogen levels by up to 55% in some cases. Talk to your pharmacist or doctor before adding it to your birth control—they may want to monitor you or adjust your dose.
What side effects might I notice?
Vitamin C can cause heartburn, diarrhea, nausea, and abdominal cramps, especially at higher doses. N-acetyl-L-cysteine may cause diarrhea, dry mouth, and nausea. Nettle leaf extract may cause constipation or diarrhea. Most people tolerate these ingredients at typical doses, but if side effects bother you, stop and ask your pharmacist.
Is this safe during pregnancy?
Vitamin C at normal amounts is considered safe in pregnancy, but high-dose supplements are not advised unless your doctor directs it. We hold no pregnancy safety data for N-acetyl-L-cysteine. Nettle leaf extract is best avoided in pregnancy due to traditional concerns about uterine effects. Talk with your doctor before taking this product if you're pregnant or planning to become pregnant.
Can I take this while breastfeeding?
Safety data for nettle leaf extract during breastfeeding has not been established, so avoid it until you talk with your doctor. Safety data for N-acetyl-L-cysteine during breastfeeding is also not on file. Discuss this product with your healthcare provider if you're nursing.
What is Quercefit?
Quercefit is a proprietary ingredient in this formula, but we don't have detailed interaction or effectiveness data on file for it. If you want specifics, contact XYMOGEN directly or ask your pharmacist.
Will this help my allergies or hay fever?
Nettle leaf extract has insufficient reliable evidence in our data to rate it for allergic rhinitis or hay fever. While some people use it for allergies, we can't say based on the evidence we hold whether it will help.

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 20x Plus label
Go deeper

The Full Monographs Behind Quercetin 20x Plus’s Ingredients

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

Herb & supplement monograph

Vitamin C

Interacts with 207 drugs

Vitamin C (ascorbic acid) is an essential nutrient your body needs but cannot make, so you must get it from food or supplements. It's important for immune function, collagen, and acts as an...

Read the full Vitamin C monograph → Herb & supplement monograph

N-acetyl Cysteine (nac)

Interacts with 294 drugs

N-acetyl cysteine (NAC) is a supplement form of the amino acid cysteine and a building block for the antioxidant glutathione. It has well-established prescription uses for acetaminophen over...

Read the full N-acetyl Cysteine (nac) monograph → Herb & supplement monograph

Stinging Nettle

Interacts with 164 drugs

Stinging nettle is a common plant used as food and in traditional medicine, most often for prostate symptoms, allergies, and joint pain. The evidence is mixed and mostly preliminary, so it i...

Read the full Stinging Nettle monograph →
Sources

Sources & How We Checked

Quercetin 20x Plus'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 160 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.

Vitamin C 51 references
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  2. Back DJ, Breckenridge AM, MacIver M, et al. Interaction of ethinyloestradiol with ascorbic acid in man. Br Med J (Clin Res Ed) 1981;282:1516.
  3. Morris JC, Beeley L, Ballantine N. Interaction of ethinyloestradiol with ascorbic acid in man [letter]. Br Med J (Clin Res Ed) 1981;283:503.
  4. Labriola D, Livingston R. Possible interactions between dietary antioxidants and chemotherapy. Oncology 1999;13:1003-8.
  5. Dwyer JH, Merz NB, Shirocre AM, et al. Progression of early atherosclerosis and intake of vitamin C and vitamin E from supplements and food. The Los Angeles Atherosclerosis Study. 41st Annual Conference on Cardiovascular Disease Epidemiology and Prevent
  6. Levine M, Rumsey SC, Daruwala R, et al. Criteria and recommendations for vitamin C intake. JAMA 1999;281:1415-23. PubMed
  7. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  8. Segal S, Kaminski S. Drug-nutrient interactions. American Druggist 1996 Jul;42-8.
  9. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press, 2000. Available at: http://www.nap.edu/books/0309069351/html/.
  10. Houston JB, Levy G. Drug biotransformation interactions in man VI: Acetaminophen and ascorbic acid. J Pharm Sci 1976;65:1218-21. PubMed
  11. Brown BG, Zhao XQ, Chait A, et al. Simvastatin and niacin, antioxidant vitamins, or the combination for the prevention of coronary disease. N Engl J Med 2001;345:1583-93. DOI
  12. Rosenthal G. Interaction of ascorbic acid and warfarin. JAMA 1971;215:1671. DOI
  13. Hume R, Johnstone JM, Weyers E. Interaction of ascorbic acid and warfarin. JAMA 1972;219:1479. DOI
  14. Smith EC, Skalski RJ, Johnson GC, Rossi GV. Interaction of ascorbic acid and warfarin. JAMA 1972;221:1166. DOI
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  14. Sahin, M., Yilmaz, H., Gursoy, A., Demirel, A. N., Tutuncu, N. B., and Guvener, N. D. Gynaecomastia in a man and hyperoestrogenism in a woman due to ingestion of nettle (Urtica dioica). N.Z.Med.J. 2007;120(1265):U2803.
  15. Randall, C., Dickens, A., White, A., Sanders, H., Fox, M., and Campbell, J. Nettle sting for chronic knee pain: a randomised controlled pilot study. Complement Ther.Med. 2008;16(2):66-72. PubMed
  16. Rayburn, K., Fleischbein, E., Song, J., Allen, B., Kundert, M., Leiter, C., and Bush, T. Stinging nettle cream for osteoarthritis. Altern.Ther.Health Med. 2009;15(4):60-61.
  17. Oliver, F., Amon, E. U., Breathnach, A., Francis, D. M., Sarathchandra, P., Black, A. K., and Greaves, M. W. Contact urticaria due to the common stinging nettle (Urtica dioica)-- histological, ultrastructural and pharmacological studies. Clin Exp Dermato PubMed
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  22. Niazi B, Ahmed K, Ahmed M, Ali S, Song K, Elias S. Drug-Induced Liver Injury from Herbal Liver Detoxification Tea. Case Rep Gastroenterol 2022;16(3):612-617. PubMed
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See these in context on the Stinging Nettle 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.

© 2021 Therapeutic Research Center, LLC

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