Drug & supplement interaction

Grapefruit + Nadolol

Nadolol brand names: Corgard, Nadolol.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Grapefruit has a moderate interaction with Nadolol. Grapefruit juice might decrease blood levels of nadolol, potentially decreasing the clinical effects of nadolol.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Grapefruit and Nadolol

Here is the interaction we found between these two, with the evidence behind it.

Moderate

NADOLOL (Corgard)

Grapefruit juice might decrease blood levels of nadolol, potentially decreasing the clinical effects of nadolol.
Nadolol is a substrate of organic anion transporting polypeptide 1A2 (OATP1A2). Some research shows that grapefruit juice and its constituent naringin can inhibit organic anion transporting polypeptides (OATP), which can reduce the bioavailability of OATP substrates. However, preliminary clinical research shows that grapefruit juice containing a low amount of naringin does not significantly affect levels of nadolol. It is not known if grapefruit juice containing higher amounts of naringin reduces the bioavailability of nadolol.
Severity Moderate Likelihood Possible Evidence B

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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the interesting twist with nadolol and grapefruit. Most grapefruit interactions cause a drug to build up, but this one works the opposite way. Your body relies on a gut transporter called OATP1A2 to pull nadolol from your intestine into your bloodstream. Grapefruit (and a compound in it called naringin) can block that transporter, so less of your dose actually gets absorbed.

The practical worry is that nadolol may not work as well, meaning your blood pressure or chest pain could be less controlled than usual. The good news is the evidence is mixed: a small study with low-naringin juice showed no real effect, while higher-naringin amounts might matter more. To stay on the safe side, keep your grapefruit habit consistent and run it by your pharmacist or doctor before making changes.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Greenblatt DJ. Analysis of drug interactions involving fruit beverages and organic anion-transporting polypeptides. J Clin Pharmacol 2009;49:1403-7. PubMed
  2. Bailey DG. Fruit juice inhibition of uptake transport: a new type of food-drug interaction. Br J Clin Pharmacol 2010;70:645-55. PubMed
  3. Glaeser, H., Bailey, D. G., Dresser, G. K., Gregor, J. C., Schwarz, U. I., McGrath, J. S., Jolicoeur, E., Lee, W., Leake, B. F., Tirona, R. G., and Kim, R. B. Intestinal drug transporter expression and the impact of grapefruit juice in humans. Clin Pharma PubMed
  4. Misaka S, Miyazaki N, Yatabe MS, Ono T, Shikama Y, Fukushima T, Kimura J. Pharmacokinetic and pharmacodynamic interaction of nadolol with itraconazole, rifampicin and grapefruit juice in healthy volunteers. J Clin Pharmacol. 2013 Jul;53(7):738-45. PubMed
  5. Tanaka S, Uchida S, Miyakawa S, Inui N, Takeuchi K, Watanabe H, Namiki N. Comparison of inhibitory duration of grapefruit juice on organic anion-transporting polypeptide and cytochrome P450 3A4. Biol Pharm Bull. 2013;36(12):1936-41. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Grapefruit Also Interacts With Other Medications

Grapefruit has 776 major, 150 moderate, 63 minor known drug interactions in our database — the Nadolol one above is one of them. If you take anything else, check it against the full list below.

Major 776 Moderate 150 Minor 63 No known interaction 1,841 (incl. Nadolol)
Taking anything else?

Check Another of Your Medications Against Grapefruit

Covers the 2,830 medications we’ve checked against Grapefruit. Pick one to open its full report.

From our Q&A

Questions About Grapefruit or Nadolol

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Grapefruit or Nadolol, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Nadolol

This page covers Grapefruit only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Nadolol page lists 145 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Green Tea (major) and Indian Snakeroot (major).

By severity: 6 major · 119 moderate · 20 minor.

From our pharmacist’s overview on the Nadolol page

“If you take nadolol (Corgard) for blood pressure, angina, or heart rhythm, treat this list with real care, and green tea is the surprise at the top. In a clinical study, green tea cut nadolol blood levels by roughly 85 percent, which can quietly leave you undertreated.”

Reviewed by 2 · Jul 18, 2026

Open the Nadolol interaction page

One more smart check

Taking Grapefruit as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,144 real supplement products containing Grapefruit, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Grapefruit. Your product may carry other ingredients that interact with Nadolol too, on top of Grapefruit — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Grapefruit and Nadolol Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Grapefruit
Top 10%

#110 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Nadolol
Steady interest

#1,419 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Grapefruit

What is Grapefruit?

Grapefruit
  • Source of vitamin C
  • Digestive complaints
  • Antimicrobial (seed extract)
  • Weight management
  • Skin and cosmetic uses

Grapefruit is a nutritious citrus fruit rich in vitamin C and other nutrients, and it is generally safe to eat. However, grapefruit is famous for serious interactions with many prescription medicines, so anyone taking medication should check with a pharmacist or doctor before consuming it regularly.

Read the full Grapefruit monograph & all interactions
Medication

About Nadolol

What Is Nadolol Used For?

Brand names: Corgard, Nadolol

Nadolol tablets are used for two main conditions: high blood pressure (hypertension) and angina pectoris (ongoing chest pain caused by reduced blood flow to the heart). Lowering high blood pressure reduces the risk of stroke and heart attack.

For high blood pressure, nadolol may be prescribed on its own or combined with other blood pressure medications, especially thiazide-type diuretics (water pills). For angina, it is used for long-term management to help reduce how often chest pain occurs.

See full Nadolol drug information
Keep checking

Other Drugs & Grapefruit

Browse every other medication we’ve checked against Grapefruit — both the ones with a known interaction and the ones without. Select any drug for the full detail.

776Major
150Moderate
63Minor
1,840No known interaction
776 Major 150 Moderate 63 Minor 1,840 No interaction
Major

776 interactions

Showing 60 of 776 major interactions — see all 776 on the Grapefruit page.

Moderate

150 interactions

Showing 60 of 150 moderate interactions — see all 150 on the Grapefruit page.

Minor

63 interactions

Showing 60 of 63 minor interactions — see all 63 on the Grapefruit page.

No interaction 1,840 drugs checked — show the list

We also checked Grapefruit against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,840 medications checked with no known interaction — see the full Grapefruit list.

See the full Grapefruit interactions page
See every supplement checked against Nadolol, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

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

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Grapefruit monograph › Uses, safety, and every drug interaction in one place Nadolol supplement interactions › Every supplement checked against Nadolol, ranked by severity Nadolol drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Grapefruit and Nadolol Together: Common Questions

Can you take Grapefruit with Nadolol?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Grapefruit and Nadolol interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Nadolol and Grapefruit?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.