Herb & supplement monograph

Grape Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Grape interacts with medications. The heart of this page is the interaction list — every drug Grape is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Grape is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Grape Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Grape drug interaction appears low for most people. None of the listed interactions are rated major, and while many carry a moderate rating, nearly all rest on lab or theoretical findings rather than proven effects in people.

Interactions deserving the most attention

The interaction with the strongest human evidence involves cyclosporine, a transplant medication with a narrow margin for error; a small human study found grape juice can meaningfully reduce how much of the drug the body absorbs. Human data also suggest grape juice may lower levels of certain medications the body clears through a particular liver enzyme. In addition, grape extracts might in theory add to the effects of blood thinners and raise bleeding risk, though this comes from lab research only.

What the rest of the list means

Grape appears on many medication lists mainly because lab and animal studies suggest it could affect enzymes the body uses to process drugs. Those predicted effects have largely not been confirmed in people, and in at least one human study a suspected effect did not occur. A long list here reflects caution, not proof of harm.

Check your medications against Grape

Based on HelloPharmacist’s Grape interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Grape

910 medications have a known interaction with Grape, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Grape using our pharmacist-reviewed interaction data.

AI summaries are generated from our Grape interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Grape combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Grape affects

Every type of medication (drug category) Grape is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 9 drug categories Grape interacts with

Anticoagulant/antiplatelet DrugsCyclosporine (neoral, Sandimmune)Cytochrome P450 1a2 (cyp1a2) SubstratesCytochrome P450 2d6 (cyp2d6) SubstratesCytochrome P450 2e1 (cyp2e1) SubstratesCytochrome P450 3a4 (cyp3a4) SubstratesMidazolam (versed)PhenacetinCytochrome P450 2c9 (cyp2c9) Substrates

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

Monograph

Grape: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

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 healthy and generally safe, the supplement evidence for treating specific conditions is mostly limited or preliminary. Talk with your pharmacist or doctor before starting a grape supplement.

Scientific name: Vitis vinifera
Family: Vitaceae
Part used: Fruit, skin, seed, and leaves
Common forms: Fresh fruit, juice, wine, capsules, tablets, grape seed extract, and standardized extracts

People commonly use it for

Antioxidant support
Heart and circulation health
Vein problems (such as varicose veins)
Eye health
General anti-inflammatory support

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallLikely safe

Grapes as food are safe for most people, and grape seed extract appears generally well tolerated in studies.

PregnancyLikely Safe

When used orally in amounts commonly found in foods. There is insufficient reliable information available about the safety of medicinal amounts during...

Read the full pregnancy detail

BreastfeedingLikely Safe

When used orally in amounts commonly found in foods. There is insufficient reliable information available about the safety of medicinal amounts during...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Grape comes from the plant Vitis vinifera, a woody vine grown around the world. Grapes have been cultivated for thousands of years for food, raisins, juice, and wine. They also have a long history of use in traditional medicine.

The fruit, skin, seeds, and leaves all contain natural compounds that people believe may have health benefits. Today, grape products are sold not only as food and drinks but also as dietary supplements, with grape seed extract being one of the most popular forms.

Grape supplements are often standardized to contain a certain amount of polyphenols or proanthocyanidins, which are the compounds thought to be responsible for many of the proposed effects.

How it works

Grapes contain a variety of natural compounds, including resveratrol, flavonoids, and proanthocyanidins (a type of polyphenol especially concentrated in the seeds and skin).

These compounds act as antioxidants, meaning they may help protect cells from a type of damage caused by unstable molecules called free radicals. They are also thought to have anti-inflammatory effects and may support healthy blood vessels and circulation.

It is important to know that much of what we understand about how these compounds work comes from laboratory and animal research. How well they work in the human body, and at what doses, is still being studied.

Effectiveness

Does Grape work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 35 uses evaluated

1 Possibly effective 5 Leans ineffective 29 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Possibly Effective Chronic venous insufficiency (CVI)