Drug & supplement interaction

Rhubarb + Bendroflumethiazide, Nadolol

Bendroflumethiazide, Nadolol brand name: Corzide.

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

Bendroflumethiazide, Nadolol falls into 2 drug categories that Rhubarb can interact with; the most serious is rated moderate. Theoretically, long-term use of anthraquinones from rhubarb might increase the risk of nephrotoxicity when used with nephrotoxic drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Rhubarb and Bendroflumethiazide, Nadolol

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Rhubarb interacts with whole categories of medication. Bendroflumethiazide, Nadolol falls into 2 of those categories, so it can interact with Rhubarb in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

NEPHROTOXIC DRUGS

1 of 2

Why this applies to Bendroflumethiazide, Nadolol

Bendroflumethiazide, Nadolol falls under NEPHROTOXIC DRUGS — the group Rhubarb interacts with.

Theoretically, long-term use of anthraquinones from rhubarb might increase the risk of nephrotoxicity when used with nephrotoxic drugs.
The anthraquinone constituents of rhubarb have been shown to induce nephrotoxicity in animal research. Additionally, in a case report, a 23-year old female presented with kidney failure after taking 6 tablets of a proprietary slimming agent (found to contain the anthraquinones emodin and aloe-emodin from rhubarb) daily for 6 weeks and then adding diclofenac 25 mg 4 times daily for 2 days. The authors postulate that the anthraquinone constituents of rhubarb contributed to the renal dysfunction, and the addition of diclofenac, a nephrotoxic drug, led to renal failure. Until more is known, advise patients to avoid taking rhubarb if they are taking other potentially nephrotoxic drugs.
Severity Moderate Likelihood Possible Evidence D

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

Corzide combines two blood pressure medicines: bendroflumethiazide (a water pill) and nadolol (a beta blocker). The concern here isn't about how rhubarb changes the drug levels. Instead, it's about your kidneys. The anthraquinone compounds in concentrated rhubarb root supplements have caused kidney stress in animal studies, and there's a case where rhubarb plus another kidney-stressing drug led to kidney failure.

Why does this matter for you? The water pill part of Corzide already makes your kidneys work harder and can shift your fluid and salt balance. Stacking a long-term rhubarb supplement on top could, in theory, add extra strain. To be clear, this evidence is weak and mostly theoretical, and eating rhubarb stalks in a pie is very different from taking concentrated capsules. Still, it's worth a quick chat with your pharmacist or doctor before using rhubarb supplements regularly.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kwan TH, Tong MK, Leung KT, et al. Acute renal failure associated with prolonged intake of slimming pills containing anthraquinones. Hong Kong Med J 2006;12:394-7.
  2. Yan, M., Zhang, L. Y., Sun, L. X., Jiang, Z. Z., and Xiao, X. H. Nephrotoxicity study of total rhubarb anthraquinones on Sprague Dawley rats using DNA microarrays. J Ethnopharmacol. 4-15-2006; PubMed
Moderate

DIURETIC DRUGS

2 of 2

Bendroflumethiazide, Nadolol also falls under DIURETIC DRUGS.

Theoretically, frequent and high doses of rhubarb might increase the risk of hypokalemia.
Rhubarb has stimulant laxative effects. Overuse of rhubarb might cause potassium depletion and compound diuretic-induced potassium loss.
Severity Moderate Likelihood Possible Evidence D

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

Corzide combines bendroflumethiazide (a water pill) with nadolol (a beta blocker). The water pill part already pulls some potassium out of your body through your urine. Here's the concern with rhubarb root: when used as a strong, regular laxative, it can flush potassium out through your bowels too. Stack those two together and your potassium could drop more than you'd like.

Low potassium can leave you feeling tired, weak, crampy, or give you an irregular heartbeat. To be clear, this is a theoretical worry based on how each works, not something proven, and a slice of rhubarb in a pie won't do it. It's really about taking concentrated rhubarb root often. If you're using it regularly, check in with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

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

Rhubarb Also Interacts With Other Medications

Rhubarb has 657 moderate known drug interactions in our database — the Bendroflumethiazide, Nadolol one above is among them. If you take anything else, check it against the full list below.

Moderate 657 No known interaction 2,173 (incl. Bendroflumethiazide, Nadolol)
Taking anything else?

Check Another of Your Medications Against Rhubarb

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

From our Q&A

Questions About Rhubarb or Bendroflumethiazide, 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 Rhubarb or Bendroflumethiazide, 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 Bendroflumethiazide, Nadolol

This page covers Rhubarb only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Bendroflumethiazide, Nadolol page lists 235 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), Asarabacca (major) and Dolomite (major).

By severity: 12 major · 199 moderate · 24 minor.

From our pharmacist’s overview on the Bendroflumethiazide, Nadolol page

“Green tea worries me most. In human studies it cut blood levels of nadolol by roughly 85 percent, enough to undermine Corzide (bendroflumethiazide with nadolol) as a blood pressure treatment, and it earns one of the 12 major ratings here.”

Reviewed by 2 · Jul 18, 2026

Open the Bendroflumethiazide, Nadolol interaction page

One more smart check

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

We hold 133 real supplement products containing Rhubarb, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Rhubarb. Your product may carry other ingredients that interact with Bendroflumethiazide, Nadolol too, on top of Rhubarb — 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 Rhubarb and Bendroflumethiazide, 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 Rhubarb
Top 25%

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

29 days ago today
Medication Bendroflumethiazide, Nadolol
Steady interest

#1,637 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 Rhubarb

What is Rhubarb?

Rhubarb
  • Constipation
  • Digestive upset
  • Menopausal symptoms
  • Kidney and liver conditions (traditional)
  • Pancreatitis (hospital/traditional use)

Rhubarb root has a long history of use as a laxative and in traditional Chinese medicine, and its edible stalks are a common food. Most medicinal claims are backed by limited or low-quality evidence, and the root can cause cramping and diarrhea. The leaves are toxic and should never be eaten, and rhubarb supplements are best avoided in pregnancy and breastfeeding.

Read the full Rhubarb monograph & all interactions
Keep checking

Other Drugs & Rhubarb

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

0Major
657Moderate
0Minor
2,172No known interaction
657 Moderate 2,172 No interaction
Moderate

657 interactions

Showing 60 of 657 moderate interactions — see all 657 on the Rhubarb page.

No interaction 2,172 drugs checked — show the list

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

Showing the 60 most looked-up of 2,172 medications checked with no known interaction — see the full Rhubarb list.

See the full Rhubarb interactions page
See every supplement checked against Bendroflumethiazide, 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
Rhubarb monograph › Uses, safety, and every drug interaction in one place Bendroflumethiazide, Nadolol supplement interactions › Every supplement checked against Bendroflumethiazide, Nadolol, ranked by severity 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 Rhubarb and Bendroflumethiazide, Nadolol Together: Common Questions

Can you take Rhubarb with Bendroflumethiazide, 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.
Why are there 2 interactions listed for Rhubarb and Bendroflumethiazide, Nadolol?
Bendroflumethiazide, Nadolol belongs to more than one drug category, and Rhubarb interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Rhubarb and Bendroflumethiazide, 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

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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.