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Dietary supplement

OPC-3 (Oligomeric Proanthocyanidins) Ingredients & Drug Interactions

by Isotonix

OPC-3 (Oligomeric Proanthocyanidins) label
See full label image
Powder 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 OPC-3 (Oligomeric Proanthocyanidins) 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

OPC-3 (Oligomeric Proanthocyanidins) is a dietary supplement by Isotonix with 6 active ingredients. Its ingredients are commonly taken for antioxidant support, heart and circulation health, vein problems (such as varicose veins).Based on those ingredients, 1,355 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Citrus Bioflavonoids Complex, Grape seed extract, Red Wine extract. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against OPC-3 (Oligomeric Proanthocyanidins) by Isotonix

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HelloPharmacist Scorecard of OPC-3 (Oligomeric Proanthocyanidins) by Isotonix

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 6 of its 6 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

Isotonix OPC-3 is a powder formula containing 6 active ingredients: grape seed extract, citrus bioflavonoids complex, potassium, bilberry extract, red wine extract, and Pycnogenol (a standardized maritime pine bark extract). These are combined with inactive ingredients including fructose, glucose, citric acid, maltodextrin, silica, calcium sulfate, modified food starch, apple pectin, and stearic acid.

The product is designed to deliver oligomeric proanthocyanidins (OPCs)—plant compounds found in grapes, berries, and pine bark that act as antioxidants.

Does it work?

Moderate 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
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: Cardiovascular and joint health antioxidant support.
  • We looked for evidence on: Cardiovascular disease (CVD), Chronic venous insufficiency (CVI), Hypercholesterolemia, Hyperlipidemia, Hypertension, Osteoarthritis — and 4 related terms.
  • The strongest evidence on file: Grape is rated "Possibly Effective" for Chronic venous insufficiency (CVI) (Natural Medicines).
  • Also on file: Maritime Pine is rated "Possibly Effective" for Chronic venous insufficiency (CVI), Osteoarthritis.
  • Also on file: Resveratrol is rated "Possibly Ineffective" for Cardiovascular disease (CVD), Hypercholesterolemia.

The evidence for OPC-3's ingredients is mixed. Grape seed extract is possibly effective for chronic venous insufficiency (a condition affecting blood flow in the legs), but possibly ineffective for chemotherapy-related nausea, hay fever, and weight loss.

Pycnogenol shows possibly effective evidence for osteoarthritis, chronic venous insufficiency, and asthma, but possibly ineffective for cholesterol levels. Bilberry extract's evidence is limited or insufficient—it's possibly ineffective for night vision, and we lack reliable evidence for cognitive decline, age-related macular degeneration, atherosclerosis, high cholesterol, and chronic venous insufficiency.

The product has no documented effectiveness rating for overall antioxidant or immune support.

The evidence, ingredient by ingredient Grape Quercetin Potassium Bilberry Resveratrol Maritime Pine

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 6 of the 6 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 6 of 6.
  • General safety write-ups exist for 6 of 6.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Grape seed extract and bilberry extract are generally well tolerated, though side effects can include abdominal pain, diarrhea, dry mouth, headache, and nausea—and in one rare case, anaphylaxis to grape skin was reported. Bilberry may discolor stools and tongue dark blue or black.

Pycnogenol is generally well tolerated but may cause gastrointestinal complaints, dizziness, vertigo, and headache; rare reports of chest pain and heart failure decompensation exist, though causality is unclear. Potassium, when taken in supplement form, can cause nausea, vomiting, abdominal pain, diarrhea, and flatulence—and at high levels, dangerously irregular heartbeat and heart block.

Concentrated grape supplements should be avoided during pregnancy due to limited safety data; Pycnogenol should be avoided in pregnancy and breastfeeding. Bilberry and potassium have limited pregnancy/breastfeeding data, so talk with your doctor before use.

Side effects, ingredient by ingredient Grape Quercetin Potassium Bilberry Resveratrol Maritime Pine

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?
  • 6 of the 6 matched ingredients can interact with medications — Bilberry, Quercetin, Resveratrol, Grape, Potassium, among others.
  • 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: 1,356 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 OPC-3, have your pharmacist check it against any blood thinners or antiplatelet drugs you're on (warfarin, apixaban, clopidogrel, aspirin)—grape, bilberry, and Pycnogenol all raise bleeding risk moderately. If you take blood pressure medications, especially ACE inhibitors, ARBs, or potassium-sparing diuretics, the potassium content here could dangerously raise your blood potassium level.

Tell your pharmacist if you're on cyclosporine, midazolam, or diabetes medications—grape and bilberry can affect how they work. Worst severity is Moderate across these interactions.

Check your own medication Run your meds through the checker above

The bottom line

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

OPC-3 is a multi-ingredient antioxidant blend most supported for chronic venous insufficiency, though evidence is modest. If you take blood thinners, blood pressure medications, diabetes drugs, cyclosporine, or sedatives, or if you have kidney disease, check this product with your pharmacist first—the interactions are real.

Pregnant or breastfeeding? Talk with your provider about safety, especially given Pycnogenol's limited data.

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

Assessment coverage: 6 of 6 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jun 20, 2024.

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 OPC-3 (Oligomeric Proanthocyanidins), straight from the product label.

Brand Isotonix
Barcode (UPC) 848570003751
Net contents 3.5 Ounce(s); 100 Gram(s)
Market status On market
Date entered into DSLD Jun 20, 2024
DSLD ID 313408
Product type Other Combinations
Supplement form Powder
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), 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 OPC-3 (Oligomeric Proanthocyanidins) by Isotonix, 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:
3.3 Gram(s)
Maximum serving Sizes:
3.3 Gram(s)
Servings per container
90
UPC/BARCODE
848570003751
IngredientAmount% DV
Total Sugars2 Gram(s)--
Calories10 Calorie(s)--
added Sugars2 Gram(s)4%
Total Carbohydrates2 Gram(s)1%
Grape seed extract25 mg--
Citrus Bioflavonoids Complex25 mg--
Potassium95 mg2%
Bilberry extract25 mg--
Red Wine extract25 mg--
Pycnogenol25 mg--

Other ingredients: Fructose, Glucose, Citric Acid, Maltodextrin, Silica, Calcium Sulfate, Food Starch, Modified, Apple Pectin, Stearic Acid

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.
Formulation

Powerful antioxidant Promotes cardiovascular and joint health Helps maintain normal cholesterol and blood glucose levels Supports normal blood vessel function

This vegan product contains no added wheat, soy, yeast, gluten, artificial flavor, salt, preservatives or milk.

Gluten free

Vegan

Brand IP Statement(s)

Isotonix The world's most advanced nutraceuticals

Pycnogenol is a registered trademark of Horphag Research Ltd. Use of this product may be protected by one or more U.S. patents and other international patents.

Formula

Pycnogenol Nature's super antioxidants

FDA Statement of Identity

An isotonic-capable Dietary Supplement

Suggested/Recommended/Usage/Directions

Directions for use: Pour 1 level, white bottle capful of powder into the overcap. Add water to the line on the overcap (2 fl oz/60 mL) and stir. As a dietary supplement, take once daily or as directed by your healthcare provider. Take 2 servings per 150 pounds of body weight daily for the first 7-10 days, and take 1 serving thereafter as a maintenance program. Maximum absorption occurs when taken on an empty stomach. This product is isotonic only if the specified amounts of powder and water are used.

Precautions

Warning: If you are currently using prescription drugs, have an ongoing medical condition, or if you are pregnant or breastfeeding, consult your healthcare provider before using this product.

Keep out of the reach of children.

Do not use if safety seal is broken. Resale on third-party websites is strictly prohibited unless specifically authorized by Market America or its corporate affiliates. If barcodes are altered or you purchase this product from an unauthorized third-party website, the product is not guaranteed by Market America or its corporate affiliates.

Storage

Store in a cool, dry place.

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.

Seals/Symbols

Vegan

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

See for yourself

OPC-3 (Oligomeric Proanthocyanidins) by Isotonix label

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

OPC-3 (Oligomeric Proanthocyanidins) 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 OPC-3 (Oligomeric Proanthocyanidins) by Isotonix

These are the 6 active ingredients this product is made of. Select any to open its full monograph.

Serving size3.3 Gram(s) Dosage formPowder Servings per container90 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.

Grape seed extract

Interacts with
910 drugs
25 mg per serving

Grapes and grape products like grape seed extract contain antioxidant compounds such as resveratrol and proanthocyanidins that may support heart and b...

Grape seed extract monograph & interactions

Citrus Bioflavonoids Complex

Interacts with
1,169 drugs
25 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...

Citrus Bioflavonoids Complex monograph & interactions

Potassium

Interacts with
62 drugs
95 mg per serving Form: Potassium Bicarbonate

Potassium is an essential mineral your body needs for nerve signals, muscle function, and a steady heartbeat, and most people get enough from a balanc...

Potassium monograph & interactions

Bilberry extract

Interacts with
275 drugs
25 mg per serving

Bilberry is a blueberry-like fruit rich in antioxidant plant compounds called anthocyanins, and it has a long history of traditional use for eye healt...

Bilberry extract monograph & interactions

Red Wine extract

Interacts with
822 drugs
25 mg per serving

Resveratrol is a plant compound found in red grapes, berries, and peanuts that is popular for heart health, anti-aging, and antioxidant support. While...

Red Wine extract monograph & interactions

Pycnogenol

Interacts with
327 drugs
25 mg per serving Form: Pine Bark Extract

Maritime pine bark extract (often sold as Pycnogenol) is a plant-based antioxidant most studied for circulation, vein, and skin health. Some research...

Pycnogenol monograph & interactions

Other (inactive) ingredients: Fructose, Glucose, Citric Acid, Maltodextrin, Silica, Calcium Sulfate, Food Starch, Modified, Apple Pectin, Stearic Acid. These complete the product’s ingredient list but are not active constituents.

Interaction report

OPC-3 (Oligomeric Proanthocyanidins) by Isotonix Drug Interactions

Want to check YOUR meds against OPC-3 (Oligomeric Proanthocyanidins)?

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
1,355Drugs
1,355 Moderate

Ingredients driving the most interactions

Citrus Bioflavonoids Complex 1,169
Grape seed extract 910
Red Wine extract 822
Pycnogenol 327
Bilberry extract 275

Individual Drug Interactions

The ingredients in OPC-3 (Oligomeric Proanthocyanidins) interact with 1,355 drugs. Click any drug to see the details.

6 of the 6 ingredients in OPC-3 (Oligomeric Proanthocyanidins) interact with drugs. Each result below shows which ingredient is responsible. Citrus Bioflavonoids Complex Grape seed extract Red Wine extract Pycnogenol Bilberry extract Potassium

Each ingredient & the kinds of drugs it affects

For each ingredient in OPC-3 (Oligomeric Proanthocyanidins) 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.

Citrus Bioflavonoids Complex21 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
Citrus Bioflavonoids Complex full monograph & interactions

Grape seed extract9 drug types · 910 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, grape extracts may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
In vitro evidence suggests that grape extracts might decrease platelet aggregation.

Likelihood Possible Evidence D
Cyclosporine (Neoral, Sandimmune)

Ingesting grape juice with cyclosporine can reduce cyclosporine absorption.
A small pharmacokinetic study in healthy young adults shows that intake of purple grape juice 200 mL along with cyclosporine can decrease the absorption of cyclosporine by up to 30% when compared with water. Separate doses of grape juice and cyclosporine by at least 2 hours to avoid this interaction.

Likelihood Possible Evidence B
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, grape juice might reduce the levels of CYP1A2 substrates.
A small pharmacokinetic study in healthy adults shows that ingestion of 200 mL of grape juice decreases phenacetin plasma levels. This is thought to be due to induction of CYP1A2.

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

Theoretically, grape seed extract may increase the levels of CYP2D6 substrates.
In vitro evidence suggests that grape seed extract might inhibit CYP2D6 enzymes. However, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2E1 (Cyp2E1) Substrates

Theoretically, grape seed extract might increase the levels of CYP2E1 substrates.
In vitro and animal research suggests that grape seed proanthocyanidin extract inhibits CYP2E1 enzymes. However, this interaction has not been reported in humans.

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

It is unclear if grape seed extract inhibits or induces CYP3A4; research is conflicting.
In vitro evidence suggests that grape seed extract might inhibit CYP3A4 enzymes. However, evidence from animal research shows that grape seed extract may induce CYP3A4 in the liver. So far, these interactions have not been reported in humans.

Likelihood Possible Evidence D
Midazolam (Versed)

Theoretically, long-term intake of grape seed extract might decrease the effects of midazolam.
Animal research shows that subchronic ingestions of grape seed extract can increase the elimination of intravenous midazolam by increasing hepatic CYP3A4 activity. Single doses of grape seed extract do not appear to affect midazolam elimination.

Likelihood Possible Evidence D
Phenacetin

Grape juice might decrease phenacetin absorption.
A small pharmacokinetic study in healthy adults shows that ingestion of 200 mL of grape juice decreases phenacetin plasma levels. This is thought to be due to induction of cytochrome P450 1A2 (CYP1A2).

Likelihood Possible Evidence B
Cytochrome P450 2C9 (Cyp2C9) Substrates

It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
In vitro evidence shows that grape seed extract or grape juice might inhibit CYP2C9 enzymes. However, a small pharmacokinetic study in healthy adults shows that drinking 8 ounces of grape juice once does not affect the clearance of flurbiprofen, a probe-drug for CYP2C9 metabolism. The effects of continued grape juice consumption are unclear.

Likelihood Unlikely Evidence D
Grape seed extract full monograph & interactions

Red Wine extract5 drug types · 822 drugs

Anticoagulant/Antiplatelet Drugs

Resveratrol may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Resveratrol seems to have antiplatelet effects.

Likelihood Possible Evidence D
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, resveratrol might increase levels of drugs metabolized by CYP1A2.
In vitro research shows that resveratrol can inhibit CYP1A2 enzymes. However, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2C19 (Cyp2C19) Substrates

Theoretically, resveratrol might increase levels of drugs metabolized by CYP2C19.
In vitro research shows that resveratrol can inhibit CYP2C19 enzymes. However, this interaction has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2E1 (Cyp2E1) Substrates

Resveratrol might increase levels of drugs metabolized by CYP2E1.
In vitro research suggests that resveratrol inhibits CYP2E1 isoenzyme. Also, a pharmacokinetic study shows that taking resveratrol 500 mg daily for 10 days prior to taking a single dose of chlorzoxazone 250 mg increases the maximum concentration of chlorzoxazone by about 54%, the area under the curve of chlorzoxazone by about 72%, and the half-life of chlorzoxazone by about 35%. Chlorzoxazone is used as a probe drug for CYP2E1.

Likelihood Probable Evidence B
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, resveratrol might increase levels of drugs metabolized by CYP3A4.
In vitro research shows that resveratrol can inhibit the CYP3A4 enzyme. However, clinical research shows that taking resveratrol 3000 mg daily for 8 weeks does not necessitate dose adjustments to medications metabolized by CYP3A4.

Likelihood Possible Evidence D
Red Wine extract full monograph & interactions

Pycnogenol3 drug types · 327 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, maritime pine bark extract might increase the risk of bleeding when used with antiplatelet or anticoagulant drugs.
Clinical research suggests that maritime pine bark extract inhibits platelet aggregation. However, the clinical significance of this effect is unclear.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, maritime pine bark extract might increase the risk of hypoglycemia when used with antidiabetes drugs.
One clinical study shows that maritime pine bark extract decreases blood sugar in patients with diabetes being treated with antidiabetes agents. Monitor blood glucose levels closely. Dose adjustments might be necessary.

Likelihood Possible Evidence B
Immunosuppressants

Theoretically, maritime pine bark extract might decrease the effectiveness of immunosuppressant therapy.
In vitro and animal research suggests that maritime pine bark extract has immunostimulant activity. This effect has not been reported in humans.

Likelihood Possible Evidence D
Pycnogenol full monograph & interactions

Bilberry extract4 drug types · 275 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, bilberry fruit extract might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
In vitro, animal, and clinical research suggest that anthocyanidin extracts from bilberry can inhibit platelet aggregation.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, bilberry leaf or fruit extract may increase the risk of hypoglycemia when taken with antidiabetes drugs.
Animal research suggests that bilberry leaf extract might have blood glucose-lowering activity. Also, one small clinical trial in patients with type 2 diabetes shows that taking bilberry fruit extract 470 mg as a single dose prior to an oral glucose tolerance test lowers plasma glucose levels when compared with placebo.

Likelihood Possible Evidence D
Cytochrome P450 2E1 (Cyp2E1) Substrates

Theoretically, bilberry fruit extract might decrease levels of drugs metabolized by CYP2E1.
Animal research shows that exposure to small concentrations of bilberry extract in drinking water for around one month increased CYP2E1 activity by 31%. However, exposure over a 2-month period did not increase CYP2E1 activity. This effect has not been reported in humans.

Likelihood Possible Evidence D
Erlotinib (Tarceva)

Theoretically, bilberry fruit extract might reduce the efficacy of erlotinib.
In vitro research suggests that bilberry fruit extract and its constituents, delphinidin and delphinidin-3-O-glucoside, inhibit the activity of erlotinib. This interaction has not been reported in humans.

Likelihood Possible Evidence D
Bilberry extract full monograph & interactions

Potassium3 drug types · 62 drugs

Ace Inhibitors (Aceis)

Using ACEIs with high doses of potassium increases the risk of hyperkalemia.
ACEIs block the actions of the renin-angiotensin-aldosterone system and reduce potassium excretion. Concomitant use of these drugs with potassium supplements increases the risk of hyperkalemia. However, concomitant use of these drugs with moderate dietary potassium intake (about 3775-5200 mg daily) does not increase serum potassium levels.

Likelihood Likely Evidence C
Angiotensin Receptor Blockers (Arbs)

Using ARBs with high doses of potassium increases the risk of hyperkalemia.
ARBs block the actions of the renin-angiotensin-aldosterone system and reduce potassium excretion. Concomitant use of these drugs with potassium supplements increases the risk of hyperkalemia. However, concomitant use of these drugs with moderate dietary potassium intake (about 3775-5200 mg daily) does not increase serum potassium levels.

Likelihood Likely Evidence C
Potassium-Sparing Diuretics

Concomitant use increases the risk of hyperkalemia.
Using potassium-sparing diuretics with potassium supplements increases the risk of hyperkalemia.

Likelihood Likely Evidence C
Potassium full monograph & interactions
The maker

Brand information

Manufacturer and brand details for OPC-3 (Oligomeric Proanthocyanidins), from the product label.

Isotonix

See all Isotonix products
Name
Market America, Inc.
Street Address
1302 Pleasant Ridge Road
City
Greensboro
State
NC
ZipCode
27409
Pharmacist Counseling Corner

OPC-3 (Oligomeric Proanthocyanidins) by Isotonix: Common Questions

Does OPC-3 (Oligomeric Proanthocyanidins) by Isotonix interact with any medications?
Yes. Based on its ingredients, OPC-3 (Oligomeric Proanthocyanidins) has a known interaction with 1,355 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
OPC-3 (Oligomeric Proanthocyanidins) contains 6 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.
Will OPC-3 help my eye health or memory?
Bilberry extract in OPC-3 is possibly ineffective for night vision, and we don't have reliable evidence to rate it for memory or age-related macular degeneration. The evidence just isn't there yet to say it'll help with those.
Is it okay to take OPC-3 while I'm pregnant?
Grape seed extract and bilberry are likely safe in pregnancy, and potassium from food is fine. But concentrated grape supplements should be avoided due to limited safety data, and Pycnogenol should be avoided entirely in pregnancy. Talk with your obstetrician or pharmacist before starting.
What side effects might I notice?
Most common are mild gastrointestinal complaints—abdominal pain, diarrhea, nausea, or flatulence. Bilberry may turn your stools dark blue or black, which is harmless. Pycnogenol may cause dizziness or headache. Serious side effects are rare but can include very high potassium levels (causing irregular heartbeat) if you're at risk.
Can I take OPC-3 with my aspirin or other blood thinner?
No—not without checking with your pharmacist first. Grape, bilberry, and Pycnogenol in this product all moderately increase bleeding risk when combined with blood thinners or aspirin-like drugs. Your pharmacist will help you decide if it's safe for your situation.
What is Pycnogenol and why is it in here?
Pycnogenol is a standardized extract from maritime pine bark, rich in proanthocyanidins like the other ingredients. It's included for antioxidant and circulatory support. Studies show it's possibly effective for osteoarthritis and asthma, and likely safe when taken orally, though long-term safety data is limited.
Is OPC-3 safe if I have kidney disease?
The potassium in this product requires caution—people with kidney disease are at higher risk for dangerously high blood potassium levels. Check with your nephrologist or pharmacist before taking any potassium supplement, even a small amount in a formula like this.

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

Not sure if OPC-3 (Oligomeric Proanthocyanidins) is safe with your meds?

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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.

OPC-3 (Oligomeric Proanthocyanidins) label
Go deeper

The Full Monographs Behind OPC-3 (Oligomeric Proanthocyanidins)’s Ingredients

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

Herb & supplement monograph

Grape

Interacts with 910 drugs

Grapes and grape products like grape seed extract contain antioxidant compounds such as resveratrol and proanthocyanidins that may support heart and blood vessel health. While the food is he...

Read the full Grape 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

Potassium

Interacts with 62 drugs

Potassium is an essential mineral your body needs for nerve signals, muscle function, and a steady heartbeat, and most people get enough from a balanced diet rich in fruits and vegetables. P...

Read the full Potassium monograph → Herb & supplement monograph

Bilberry

Interacts with 275 drugs

Bilberry is a blueberry-like fruit rich in antioxidant plant compounds called anthocyanins, and it has a long history of traditional use for eye health, circulation, and mild diarrhea. While...

Read the full Bilberry monograph → Herb & supplement monograph

Resveratrol

Interacts with 822 drugs

Resveratrol is a plant compound found in red grapes, berries, and peanuts that is popular for heart health, anti-aging, and antioxidant support. While lab and animal studies are promising, s...

Read the full Resveratrol monograph → Herb & supplement monograph

Maritime Pine

Interacts with 327 drugs

Maritime pine bark extract (often sold as Pycnogenol) is a plant-based antioxidant most studied for circulation, vein, and skin health. Some research is promising, but many studies are small...

Read the full Maritime Pine monograph →
Sources

Sources & How We Checked

OPC-3 (Oligomeric Proanthocyanidins)'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 124 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.

Grape 34 references
  1. Kiesewetter H, Koscielny J, Kalus U, et al. Efficacy of orally administered extract of red vine leaf AS 195 (folia vitis viniferae) in chronic venous insufficiency (stages I-II). A randomized, double-blind, placebo-controlled trial. Arzneimittelforschung
  2. Xiao Dong S, Zhi Ping Z, Zhong Xiao W, et al. Possible enhancement of the first-pass metabolism of phenacetin by ingestion of grape juice in Chinese subjects. Br J Clin Pharmacol 1999;48:638-40. PubMed
  3. Vaswani SK, Hamilton RG, Carey RN, et al. Anaphylaxis recurrent urticaria and angioedema from grape hypersensitivity. J Allergy Clin Immunol 1998;101:S31.
  4. Chevallier A. The Encyclopedia of Medicinal Plants. London, UK: Dorling Kindersley, Ltd., 1996.
  5. Bernstein DI, Bernstein CK, Deng C, et al. Evaluation of the clinical efficacy and safety of grapeseed extract in the treatment of fall seasonal allergic rhinitis: a pilot study. Ann Allergy Asthma Immunol 2002;88:272-8.. PubMed
  6. Greenblatt DJ, von Moltke LL, Perloff ES, et al. Interaction of flurbiprofen with cranberry juice, grape juice, tea, and fluconazole: in vitro and clinical studies. Clin Pharmacol Ther 2006;79:125-33. PubMed
  7. Ward NC, Hodgson JM, Croft KD, et al. The combination of vitamin C and grape-seed polyphenols increases blood pressure: a randomized, double-blind, placebo-controlled trial. J Hypertens 2005;23:427-34.. PubMed
  8. Ray, S. D., Parikh, H., Hickey, E., Bagchi, M., and Bagchi, D. Differential effects of IH636 grape seed proanthocyanidin extract and a DNA repair modulator 4-aminobenzamide on liver microsomal cytochrome 4502E1-dependent aniline hydroxylation. Mol Cell B PubMed
  9. O'Byrne, D. J., Devaraj, S., Grundy, S. M., and Jialal, I. Comparison of the antioxidant effects of Concord grape juice flavonoids alpha-tocopherol on markers of oxidative stress in healthy adults. Am J Clin.Nutr. 2002;76(6):1367-1374.
  10. Schaefer, E., Peil, H., Ambrosetti, L., and Petrini, O. Oedema protective properties of the red vine leaf extract AS 195 (Folia vitis viniferae) in the treatment of chronic venous insufficiency. A 6-week observational clinical trial. Arzneimittelforschun PubMed
  11. Nishikawa, M., Ariyoshi, N., Kotani, A., Ishii, I., Nakamura, H., Nakasa, H., Ida, M., Nakamura, H., Kimura, N., Kimura, M., Hasegawa, A., Kusu, F., Ohmori, S., Nakazawa, K., and Kitada, M. Effects of continuous ingestion of green tea or grape seed extra
  12. de Lange, D. W., Scholman, W. L., Kraaijenhagen, R. J., Akkerman, J. W., and van de Wiel, A. Alcohol and polyphenolic grape extract inhibit platelet adhesion in flowing blood. Eur.J Clin.Invest 2004;34(12):818-824. PubMed
  13. Samet, J. M. and Coultas, D. B. Reduced forced vital capacity in California grape workers. What does it mean? Am Rev.Respir.Dis 1992;145(2 Pt 1):255-256. PubMed
  14. Gamsky, T. E., McCurdy, S. A., Samuels, S. J., and Schenker, M. B. Reduced FVC among California grape workers. Am Rev.Respir.Dis 1992;145(2 Pt 1):257-262. PubMed
  15. de Lange, D. W., Verhoef, S., Gorter, G., Kraaijenhagen, R. J., van de Wiel, A., and Akkerman, J. W. Polyphenolic grape extract inhibits platelet activation through PECAM-1: an explanation for the French paradox. Alcohol Clin.Exp.Res 2007;31(8):1308-1314 PubMed
  16. Etheridge, A. S., Black, S. R., Patel, P. R., So, J., and Mathews, J. M. An in vitro evaluation of cytochrome P450 inhibition and P-glycoprotein interaction with goldenseal, Ginkgo biloba, grape seed, milk thistle, and ginseng extracts and their constitu
  17. Krikorian, R., Nash, T. A., Shidler, M. D., Shukitt-Hale, B., and Joseph, J. A. Concord grape juice supplementation improves memory function in older adults with mild cognitive impairment. Br J Nutr. 2010;103(5):730-734. PubMed
  18. Ingersoll, G. L., Wasilewski, A., Haller, M., Pandya, K., Bennett, J., He, H., Hoffmire, C., and Berry, C. Effect of concord grape juice on chemotherapy-induced nausea and vomiting: results of a pilot study. Oncol.Nurs.Forum 2010;37(2):213-221. PubMed
  19. Oliveira-Freitas, V. L., Dalla, Costa T., Manfro, R. C., Cruz, L. B., and Schwartsmann, G. Influence of purple grape juice in cyclosporine bioavailability. J Ren Nutr. 2010;20(5):309-313. PubMed
  20. Hollis, J. H., Houchins, J. A., Blumberg, J. B., and Mattes, R. D. Effects of concord grape juice on appetite, diet, body weight, lipid profile, and antioxidant status of adults. J Am Coll.Nutr. 2009;28(5):574-582. PubMed
  21. Dohadwala, M. M., Hamburg, N. M., Holbrook, M., Kim, B. H., Duess, M. A., Levit, A., Titas, M., Chung, W. B., Vincent, F. B., Caiano, T. L., Frame, A. A., Keaney, J. F., Jr., and Vita, J. A. Effects of Concord grape juice on ambulatory blood pressure in
  22. Rabe, E., Stucker, M., Esperester, A., Schafer, E., and Ottillinger, B. Efficacy and tolerability of a red-vine-leaf extract in patients suffering from chronic venous insufficiency--results of a double-blind placebo-controlled study. Eur.J Vasc.Endovasc. PubMed
  23. Trotta, M., Cesaretti, M., Conzi, R., Derchi, L. E., and Borgonovo, G. Elderly male with mesogastric pain. Small bowel obstruction caused by an intact fresh grape. Ann.Emerg.Med 2011;58(4):e1-e2. PubMed
  24. McCurdy, S. A., Wiggins, P., Schenker, M. B., Munn, S., Shaieb, A. M., Weinbaum, Z., Goldsmith, D., McGillis, S. T., Berman, B., and Samuels, S. Assessing dermatitis in epidemiologic studies: occupational skin disease among California grape and tomato ha
  25. Winter, C. K. and Kurtz, P. H. Factors influencing grape worker susceptibility to skin rashes. Bull.Environ.Contam Toxicol. 1985;35(3):418-426. PubMed
  26. Yamasaki, R., Dekio, S., and Jidoi, J. Contact dermatitis from grape bud. Contact Dermatitis 1985;12(4):226-227. PubMed
  27. Cox, J. and Grigg, M. Small bowel obstruction by an intact grape. J Am Geriatr.Soc 1986;34(7):550. PubMed
  28. Faircloth, D. E. and Robison, W. J. Obstruction of the sigmoid colon by grape seeds. JAMA 11-27-1981;246(21):2430. PubMed
  29. Marguerie, C. and Drouet, M. [Occupational eosinophilic lung in a grape grower: role of sulfites]. Allerg.Immunol.(Paris) 1995;27(5):163-167.
  30. Brito, FF., Martinez, A., Palacios, R., Mur, P., Gomez, E., Galindo, P. A., Borja, J., and Martinez, J. Rhinoconjunctivitis and asthma caused by vine pollen: a case report. J Allergy Clin Immunol 1999;103(2 Pt 1):262-266. PubMed
  31. Ras RT, Zock PL, Zebregs YE, et al. Effect of polyphenol-rich grape seed extract on ambulatory blood pressure in subjects with pre- and stage I hypertension. Br J Nutr 2013;110(12):2234-41. PubMed
  32. Berry AC, Nakshabendi R, Abidali H, et al. Adverse effects of grape seed extract supplement: A clinical case and long-term follow-up. J Diet Suppl. 2016;13(2):232-5. PubMed
  33. Martínez-Maqueda D, Zapatera B, Gallego-Narbón A, Vaquero MP, Saura-Calixto F, Pérez-Jiménez J. A 6-week supplementation with grape pomace to subjects at cardiometabolic risk ameliorates insulin sensitivity, without affecting other metabolic syndrome mark
  34. Moon SW, Shin YU, Cho H, Bae SH, Kim HK; and for the Mogen Study Group. Effect of grape seed proanthocyanidin extract on hard exudates in patients with non-proliferative diabetic retinopathy. Medicine (Baltimore) 2019;98(21):e15515. PubMed

See these in context on the Grape monograph →

Quercetin 26 references
  1. Shoskes DA, Zeitlin SI, Shahed A, Rajfer J. Quercetin in men with category III chronic prostatitis: A preliminary prospective, double-blind, placebo-controlled trial. Urol 1999;54:960-3. PubMed
  2. Starvic B. Quercetin in our diet: from potent mutagen to probable anticarcinogen. Clin Biochem 1994;27:245-8. PubMed
  3. Ferry DR, Smith A, Malkhandi J, et al. Phase I clinical trial of the flavonoid quercetin: Pharmacokinetics and evidence for in vivo tyrosine kinase inhibition. Clin Cancer Res 1996;2:659-67..
  4. 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
  5. Edwards RL, Lyon T, Litwin SE, et al. Quercetin reduces blood pressure in hypertensive subjects. J Nutr 2007;137:2405-11.
  6. Kim KA, Park PW, Kim HK, et al. Effect of quercetin on the pharmacokinetics of rosiglitazone, a CYP2C8 substrate, in healthy subjects. J Clin Pharmacol 2005;45:941-6. PubMed
  7. 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
  8. 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
  9. 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
  10. Vaclavikova R, Horsky S, Simek P, Gut I. Paclitaxel metabolism in rat and human liver microsomes is inhibited by phenolic antioxidants. Naunyn Schmiedebergs Arch Pharmacol 2003;368:200-9. PubMed
  11. Di Bari L, Ripoli S, Pradhan S, Salvadori P. Interactions between quercetin and warfarin for albumin binding: A new eye on food/drug interference. Chirality 2010;22:593-6. PubMed
  12. Lamson, D. W. and Brignall, M. S. Antioxidants and cancer, part 3: quercetin. Altern.Med.Rev. 2000;5(3):196-208.
  13. 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
  14. Wang SY, Duan KM, Li Y, et al. Effect of quercetin on P-glycoprotein transport ability in Chinese healthy subjects. Eur J Clin Nutr 2013;67(4):390-4. PubMed
  15. Nguyen MA, Staubach P, Wolffram S, Langguth P. Effect of single-dose and short-term administration of quercetin on the pharmacokinetics of talinolol in humans - Implications for the evaluation of transporter-mediated flavonoid-drug interactions. Eur J Pha PubMed
  16. Wu LX, Guo CX, Chen WQ, et al. Inhibition of the organic anion-transporting polypeptide 1B1 by quercetin: an in vitro and in vivo assessment. Br J Clin Pharmacol 2012;73(5):750-7.
  17. Ahrens MJ, Thompson DL. Effect of emulin on blood glucose in type 2 diabetics. J Med Food. 2013;16(3):211-5. PubMed
  18. Larson A, Witman MA, Guo Y, et al. Acute, quercetin-induced reductions in blood pressure in hypertensive individuals are not secondary to lower plasma angiotensin-converting enzyme activity or endothelin-1: nitric oxide. Nutr Res. 2012;32(8):557-64. PubMed
  19. 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
  20. 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
  21. 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.
  22. Li C, Wang X, Bi Y, et al. Potent Inhibitors of Organic Anion Transporters 1 and 3 From Natural Compounds and Their Protective Effect on Aristolochic Acid Nephropathy. Toxicol Sci. 2020;175(2):279-291. PubMed
  23. Ni Y, Duan Z, Zhou D, et al. Identification of Structural Features for the Inhibition of OAT3-Mediated Uptake of Enalaprilat by Selected Drugs and Flavonoids. Front Pharmacol. 2020;11:802. PubMed
  24. Song YK, Yoon JH, Woo JK, et al. Quercetin is a flavonoid breast cancer resistance protein inhibitor with an impact on the oral pharmacokinetics of sulfasalazine in rats. Pharmaceutics 2020;12(5):397. PubMed
  25. Ahmad E, Jahangir M, Ismail MA, et al. Influence of quercetin pretreatment on pharmacokinetics of warfarin in rats. Curr Drug Saf 2022. PubMed
  26. Nambiar A, Kellogg D 3rd, Justice J, et al. Senolytics dasatinib and quercetin in idiopathic pulmonary fibrosis: results of a phase I, single-blind, single-center, randomized, placebo-controlled pilot trial on feasibility and tolerability. EBioMedicine 20 PubMed

See these in context on the Quercetin monograph →

Potassium 12 references
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  2. Gennaro A. Remington: The Science and Practice of Pharmacy. 19th ed. Lippincott: Williams & Wilkins, 1996.
  3. Whelton PK, He J, Cutler JA, et al. Effects of oral potassium on blood pressure. Meta-analysis of randomized controlled clinical trials. JAMA 1997;277:1624-32. PubMed
  4. Phillips, C. O., Kashani, A., Ko, D. K., Francis, G., and Krumholz, H. M. Adverse effects of combination angiotensin II receptor blockers plus angiotensin-converting enzyme inhibitors for left ventricular dysfunction: a quantitative review of data from ra DOI
  5. Altieri, P. I., Herrero, C., Suero, R., and Ortiz, A. Bleeding duodenal ulcer in a patient taking slow-releasing potassium tablets. Bol.Asoc.Med P.R. 1977;69(8):276.
  6. Raf, L. E. Enteric-coated potassium chloride tablets and ulcer of the small intestine. Acta Chir Scand Suppl 1967;(374):1-87.
  7. Potassium chloride oral solution [package insert]. Allentown, PA: Lehigh Valley Technologies, Inc.; 2014.
  8. Potassium chloride injection [package insert]. Lake Forest, IL: Hospira Inc.; 2009.
  9. Patel RB, Tannenbaum S, Viana-Tejedor A, et al. Serum potassium levels, cardiac arrhythmias, and mortality following non-ST-elevation myocardial infarction or unstable angina: insights from MERLIN-TIMI 36. Eur Heart J Acute Cardiovasc Care 2017 Feb;6(1):1 PubMed
  10. Malta D, Arcand J, Ravindran A, Floras V, Allard JP, Newton GE. Adequate intake of potassium does not cause hyperkalemia in hypertensive individuals taking medications that antagonize the renin angiotensin aldosterone system. Am J Clin Nutr 2016 Oct;104(4 PubMed
  11. Keskin M, Kaya A, Tatlisu MA, et al. The effect of serum potassium level on in-hospital and long-term mortality in ST elevation myocardial infarction. Int J cardiol. 2016 Oct 15;221:505-10.
  12. Stallings VA, Harrison M, Oria M; Committee to Review the Dietary Reference Intakes for Sodium and Potassium, Food and Nutrition Board, Health and Medicine Division, National Academies of Sciences, Engineering, and Medicine. Washington (DC): National Acad

See these in context on the Potassium monograph →

Bilberry 14 references
  1. Cignarella A, Nastasi M, Cavalli E, Puglisi L. Novel lipid-lowering properties of Vaccinium myrtillus L. leaves, a traditional antidiabetic treatment, in several models of rat dyslipidaemia: a comparison with ciprofibrate. Thromb Res 1996;84:311-22. PubMed
  2. Morazzoni P, Magistretti MJ. Activity of Myrtocyan, an anthosyanoside complex from Vaccinium myrtillus (VMA), on platelet aggregation and adhesiveness. Fitoterapia 1990;61:13-21.
  3. Erlund, I., Koli, R., Alfthan, G., Marniemi, J., Puukka, P., Mustonen, P., Mattila, P., and Jula, A. Favorable effects of berry consumption on platelet function, blood pressure, and HDL cholesterol. Am J Clin Nutr 2008;87(2):323-331. PubMed
  4. Hawrelak, J. A. and Myers, S. P. Effects of two natural medicine formulations on irritable bowel syndrome symptoms: a pilot study. J Altern Complement Med 2010;16(10):1065-1071. PubMed
  5. Morazzoni P and Magistretti MJ. Effects of Vaccinium myrtillus anthocyanosides on prostacyclin-like activity in rat arterial issue. Fitoterapia 1986;57:11-14.
  6. Pulliero G, Montin S, Bettini V, and et al. Ex vivo study of the inhibitory effects of Vaccinium myrtillus anthocyanosides on human platelet aggregation. Fitoterapia 1989;60:69-75.
  7. Bottecchia D. Preliminary report on the inhibitory effect of vaccinium myrtillus anthocyanosides on platelet aggregation and clot retraction. Fitoterapia 1987;48:3-8.
  8. Fdez, M., Zaragoza, F., and Alvarez, P. In vitro platelet aggregation effects of anthocyanosides of vaccinium myrtilus L. Anales de la Real Academia de Farmacia 1983;49:79-90.
  9. Biedermann L, Mwinyi J, Scharl M, Frei P, Zeitz J, Kullak-Ublick GA, et al. Bilberry ingestion improves disease activity in mild to moderate ulcerative colitis-an open pilot study. 2013 May;7(4):271-9. PubMed
  10. Hoggard N, Cruickshank M, Moar KM, Bestwick C, Holst J, Russell W, et al. A single supplement of a standardized bilberry (Vaccinium myrtillus L.) extract (36% wet weight anthocyanins) modifies glycaemic response in individuals with type 2 diabetes control
  11. Aichinger G, Pahlke G, Nagel LJ, Berger W, Marko D. Bilberry extract, its major phenolic compounds, and soy isoflavone genistein antagonize the cytostatic drug erlotinib in human epithelial cells. Food Funct 2016;7(8):3628-36.
  12. Prokop J, Lněničková K, Cibicek N, et al. Effect of bilberry extract (Vaccinium myrtillus L.) on drug-metabolizing enzymes in rats. Food Chem Toxicol 2019;129:382-90. PubMed
  13. Chan SW, Chu TTW, Choi SW, Benzie IFF, Tomlinson B. Impact of short-term bilberry supplementation on glycemic control, cardiovascular disease risk factors, and antioxidant status in Chinese patients with type 2 diabetes. Phytother Res 2021. Online ahead o PubMed
  14. Bøhn SK, Myhrstad MCW, Thoresen M, et al. Bilberry/red grape juice decreases plasma biomarkers of inflammation and tissue damage in aged men with subjective memory impairment -a randomized clinical trial. BMC Nutr 2021;7(1):75. PubMed

See these in context on the Bilberry monograph →

Resveratrol 24 references
  1. Soleas GJ, Diamandis EP, Goldberg DM. Resveratrol: a molecule whose time has come? And gone? Clin Biochem 1997;30:91-113.
  2. Pace-Asciak CR, Rounova O, Hahn SE, et al. Wines and grape juices as modulators of platelet aggregation in healthy human subjects. Clin Chim Acta 1996;246:163-82. PubMed
  3. Bertelli AA, Giovannini L, Bernini W, et al. Antiplatelet activity of cis-resveratrol. Drugs Exp Clin Res 1996;22:61-3.
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  16. Brown, V. A., Patel, K. R., Viskaduraki, M., Crowell, J. A., Perloff, M., Booth, T. D., Vasilinin, G., Sen, A., Schinas, A. M., Piccirilli, G., Brown, K., Steward, W. P., Gescher, A. J., and Brenner, D. E. Repeat dose study of the cancer chemopreventive
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See these in context on the Resveratrol monograph →

Maritime Pine 14 references
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See these in context on the Maritime Pine 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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