Maximum Strength Grape Seed Extract 500 mg Ingredients & Drug Interactions
by NOW
What is this page for?
First and foremost: checking Maximum Strength Grape Seed Extract 500 mg 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
Maximum Strength Grape Seed Extract 500 mg is a dietary supplement by NOW with 1 active ingredient. Its ingredients are commonly taken for antioxidant support, heart and circulation health, vein problems (such as varicose veins).Based on those ingredients, 910 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Grape Seed Extract. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against Maximum Strength Grape Seed Extract 500 mg by NOW
Ask about any prescription or over-the-counter medication and we check it for interactions with Maximum Strength Grape Seed Extract 500 mg by NOW — and tell you which ingredient is responsible.
AI summaries are generated from our interaction database for education only — always confirm with your pharmacist. How we use AI
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HelloPharmacist Scorecard of Maximum Strength Grape Seed Extract 500 mg by NOW
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.
What’s inside
Full disclosure
This product contains one active ingredient: 500 mg of grape seed extract per capsule. Grape seed extract is a concentrated form derived from grape seeds and contains compounds called proanthocyanidins.
The capsule itself is made from hypromellose (a plant-based capsule material), microcrystalline cellulose, and stearic acid — these are inactive ingredients that help form and stabilize the capsule.
Does it work?
Moderate evidence
The evidence for grape seed extract is limited. It's rated possibly effective for chronic venous insufficiency (CVI) — a condition where blood doesn't return efficiently from the legs — suggesting some benefit based on available studies.
For chemotherapy-induced nausea and vomiting, allergic rhinitis (hay fever), and obesity, the evidence leans toward it being possibly ineffective, meaning studies haven't shown meaningful benefit for these uses.
How safe is it?
Well-documented data
Grape seed extract is generally well tolerated. The most common side effects reported in studies are abdominal pain, diarrhea, dry mouth, indigestion, headache, joint pain, and nausea — most people don't experience these.
A rare serious reaction, anaphylaxis to grape skin, has been reported. During pregnancy, concentrated grape supplements should be avoided due to limited safety data; whole grapes as food are fine.
For breastfeeding, there isn't enough information on concentrated supplements, so talk with your doctor or pharmacist about whether it's right for you.
Meds to double-check
Moderate interaction found
Check with your doctor or pharmacist before taking this if you're on blood thinners or antiplatelet drugs (like warfarin or aspirin) — grape seed extract may increase bleeding risk. Also double-check if you take cyclosporine, certain sedatives like midazolam, or any medications processed by CYP1A2, CYP2D6, CYP2E1, or CYP3A4 liver enzymes — this supplement can change how well they work.
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.
If you have chronic venous insufficiency and want to explore grape seed extract, it may be worth a conversation with your doctor — the evidence suggests it could help. However, if you take blood thinners, medications processed by certain liver enzymes, or cyclosporine, you'll need to check with your own doctor or pharmacist first because this supplement can affect how those drugs work.
Pregnant people should avoid concentrated grape supplements, though whole grapes are fine.
Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI
Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Jun 22, 2023.
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
General information
Key facts about Maximum Strength Grape Seed Extract 500 mg, straight from the product label.
| Brand | NOW |
|---|---|
| Barcode (UPC) | 733739033956 |
| Net contents | 90 Veg Capsule(s) |
| Market status | On market |
| Date entered into DSLD | Jun 22, 2023 |
| DSLD ID | 292051 |
| Product type | Botanical |
| Supplement form | Capsule |
| Dietary claims / uses | All Other, Structure/Function |
| Intended target group(s) | Vegan, Vegetarian, Adult (18 - 50 Years), Dairy Free |
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 Maximum Strength Grape Seed Extract 500 mg by NOW, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| Grape Seed Extract | 500 mg | -- |
Other ingredients: Hypromellose, Microcrystalline Cellulose, Stearic Acid
Tap any ingredient to jump to its full detail below.
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
Suggested usage: Take 1 capsule daily with a meal.
Formula
Now Grape Seed Extract is a highly concentrated extract with a minimum of 90% polyphenols, including oligomeric proanthocyanidins (OPCs), which are the potent water-soluble free radical scavenging compounds found in grape seeds.
The maximum strength product has twice the grape seed extract (500 mg per capsule) as in our extra strength product (250 mg per capsule).
Formulation
A growing body of research indicates that grape seed OPCs may help to support the health of vascular, bone, kidney, brain and other tissues by supporting a healthy, balanced immune response to normal metabolic stress.
Natural color variation may occur in this product.
Free radical scavenger Vascular health Healthy immune response General health
Non-GMO
Vegetarian/Vegan
Made and quality tested in the USA with globally sourced ingredients.
Not made with yeast, wheat, gluten, soy. milk, egg, fish, shellfish, tree nut or sesame ingredients.
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.
Precautions
Caution: For adults only.
Consult physician if pregnant/nursing, taking medication, or have a medical condition.
Keep out of reach of children.
Not made with yeast, wheat, gluten, soy. milk, egg, fish, shellfish, tree nut or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.
Storage
Store in a cool, dry place after opening.
FDA Statement of Identity
Dietary Supplement
General Statements
Family owned since 1968.
Seals/Symbols
GMP Quality Assured
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
Maximum Strength Grape Seed Extract 500 mg by NOW label
The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.
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)The Ingredients in Maximum Strength Grape Seed Extract 500 mg by NOW
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size1 Veg Capsule(s) Dosage formCapsule Servings per container90 Amounts shown are per serving.
Grape Seed Extract
Interacts with910 drugs
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 & interactionsOther (inactive) ingredients: Hypromellose, Microcrystalline Cellulose, Stearic Acid. These complete the product’s ingredient list but are not active constituents.
Maximum Strength Grape Seed Extract 500 mg by NOW Drug Interactions
HelloPharmacist Interaction Report
NOW's Maximum Strength Grape Seed Extract does interact with several medication types.
Through its grape seed extract, the biggest concern is with blood thinners and antiplatelet drugs (medications that prevent clotting) — grape extracts may increase bleeding risk if you're already on these medications.
Read the full breakdown — every affected drug type, severity by severity
Grape seed extract may affect how your body processes a number of drugs broken down by liver enzymes. It can theoretically increase levels of medications processed by CYP2D6 and CYP2E1 enzymes, and the picture is unclear with CYP3A4 substrates — in vitro work suggests it might inhibit them, but animal studies hint it may speed their breakdown instead.
None of these interactions have been confirmed in humans yet, but they're worth checking. Additionally, grape seed extract may decrease levels of CYP1A2 substrates and is documented to reduce cyclosporine (an immunosuppressant) absorption by up to 30% — separating doses by at least 2 hours may help.
Long-term use might also decrease how well midazolam (a sedative) works.
Altogether, these interactions span 911 individual medications. Use the medication checker on this page to look up your specific drugs before you start.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against Maximum Strength Grape Seed Extract 500 mg?
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 checkerIngredients driving the most interactions
Individual Drug Interactions
The ingredients in Maximum Strength Grape Seed Extract 500 mg interact with 910 drugs. Click any drug to see the details.
1 of the 1 ingredient in Maximum Strength Grape Seed Extract 500 mg interact with drugs. Each result below shows which ingredient is responsible. Grape Seed Extract
AzilsartanEdarbi
How Azilsartan interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Azilsartan interactionAzilsartan, ChlorthalidoneEdarbyclor
How Azilsartan, Chlorthalidone interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Azilsartan, Chlorthalidone interactionBupivacaine, MeloxicamZynrelef Kit
How Bupivacaine, Meloxicam interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Bupivacaine, Meloxicam interactionCelecoxibCelebrex, Elyxyb
How Celecoxib interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Celecoxib interactionFlurbiprofenAnsaid, Flurbiprofen, Flurprofen, Froben, Froben SR, Ocufen
How Flurbiprofen interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Flurbiprofen interactionFluvastatinLescol, Lescol XL
How Fluvastatin interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Fluvastatin interactionFosphenytoinCerebyx
How Fosphenytoin interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Fosphenytoin interactionFosphenytoin SodiumSesquient
How Fosphenytoin Sodium interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Fosphenytoin Sodium interactionGliclazideDiamicron
How Gliclazide interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Gliclazide interactionGlimepirideAmaryl
How Glimepiride interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Glimepiride interactionGlipizideGlucotrol, Glucotrol XL
How Glipizide interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Glipizide interactionGlipizide, MetforminMetaglip
How Glipizide, Metformin interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Glipizide, Metformin interactionGlyburideAlbert Glyburide, Diabeta, Glycron, Glynase, Glynase PresTab, Micronase +1 more
How Glyburide interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Glyburide interactionGlyburide, MetforminGlucovance
How Glyburide, Metformin interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Glyburide, Metformin interactionHydrochlorothiazide, IrbesartanAvalide
How Hydrochlorothiazide, Irbesartan interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Hydrochlorothiazide, Irbesartan interactionHydrochlorothiazide, ValsartanDiovan HCT
How Hydrochlorothiazide, Valsartan interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Hydrochlorothiazide, Valsartan interactionIndomethacinIndo-Lemmon, Indocin, Indocin SR, Indomethagan, Tivorbex
How Indomethacin interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Indomethacin interactionIrbesartanAprovel, Avapro
How Irbesartan interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Irbesartan interactionIrbesartan, HydrochlorothiazideCoAprovel
How Irbesartan, Hydrochlorothiazide interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Irbesartan, Hydrochlorothiazide interactionLesinuradZurampic
How Lesinurad interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Lesinurad interactionLesinurad, AllopurinolDuzallo
How Lesinurad, Allopurinol interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Lesinurad, Allopurinol interactionLumiracoxibPrexige
How Lumiracoxib interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Lumiracoxib interactionMefenamic AcidPonstel
How Mefenamic Acid interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Mefenamic Acid interactionMeloxicamAnjeso, Mobic, Qmiiz ODT, Vivlodex
How Meloxicam interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Meloxicam interactionMephenytoinMesantoin
How Mephenytoin interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Mephenytoin interactionMetformin, RosiglitazoneAvandamet
How Metformin, Rosiglitazone interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Metformin, Rosiglitazone interactionMontelukast SodiumSingulair
How Montelukast Sodium interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Montelukast Sodium interactionNateglinideStarlix
How Nateglinide interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Nateglinide interactionPhenobarbital, PhenytoinDilantin with PB
How Phenobarbital, Phenytoin interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Phenobarbital, Phenytoin interactionPhenytoinDi-Phen, Dilantin, Dilantin Infatabs, Dilantin injection, Dilantin Kapseals, Phenytek
How Phenytoin interacts with Maximum Strength Grape Seed Extract 500 mg — through 1 ingredient. Tap an ingredient for the detail:
Grape Seed ExtractCytochrome P450 2c9 (cyp2c9) Substrates Minor
Interaction Summary
It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.
Read the full Grape Seed Extract + Phenytoin interactionEach ingredient & the kinds of drugs it affects
For each ingredient in Maximum Strength Grape Seed Extract 500 mg with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.
Grape Seed Extract
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.
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.
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.
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.
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.
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.
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.
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).
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.
Brand information
Manufacturer and brand details for Maximum Strength Grape Seed Extract 500 mg, from the product label.
NOW
See all NOW products- Name
- NOW Foods
- Street Address
- 395 S. Glen Ellyn Rd.
- City
- Bloomingdale
- State
- IL
- ZipCode
- 60108
- Web Address
- nowfoods.com
Maximum Strength Grape Seed Extract 500 mg by NOW: Common Questions
Does Maximum Strength Grape Seed Extract 500 mg by NOW interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
Is grape seed extract safe to take if I'm pregnant or breastfeeding?
What are the most common side effects?
Does this work for hay fever or allergies?
What is grape seed extract actually for?
Can I take this with cyclosporine?
Will this interfere with my blood thinner?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if Maximum Strength Grape Seed Extract 500 mg is safe with your meds?
Our pharmacists answer your medication & supplement questions — free.
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.
The Full Monographs Behind Maximum Strength Grape Seed Extract 500 mg’s Ingredients
Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.
Sources & How We Checked
Maximum Strength Grape Seed Extract 500 mg'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.
- NIH Dietary Supplement Label Database (DSLD) — The official product label on file for this supplement.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference behind the ingredient interaction data.
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 34 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
- 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
- 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
- Vaswani SK, Hamilton RG, Carey RN, et al. Anaphylaxis recurrent urticaria and angioedema from grape hypersensitivity. J Allergy Clin Immunol 1998;101:S31.
- Chevallier A. The Encyclopedia of Medicinal Plants. London, UK: Dorling Kindersley, Ltd., 1996.
- 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
- 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
- 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
- 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
- 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.
- 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
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