Drug & supplement interaction

Glucosamine + Valrubicin

Valrubicin brand name: Valstar.

Moderate Interaction
Medically reviewed by · Updated April 2023
The bottom line Moderate

Glucosamine has a moderate interaction with Valrubicin. Theoretically glucosamine may induce resistance to topoisomerase II inhibitors.

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

Glucosamine and Valrubicin

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

Moderate

TOPOISOMERASE II INHIBITORS

Why this applies to Valrubicin

Valrubicin falls under TOPOISOMERASE II INHIBITORS — the group Glucosamine interacts with.

Theoretically glucosamine may induce resistance to topoisomerase II inhibitors.
In vitro research suggests that glucosamine might induce resistance to etoposide (VP16, VePesid) and doxorubicin (Adriamycin) by reducing inhibition of topoisomerase II, an enzyme required for DNA replication in tumor cells. This effect has not been reported in humans.
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

Here's the gist for valrubicin (Valstar), the bladder cancer treatment that's placed directly into the bladder. It works by interfering with an enzyme called topoisomerase II that cancer cells need to copy their DNA. Lab studies (in test tubes, not in people) hint that glucosamine might make cancer cells less responsive to drugs that block this enzyme, meaning the medicine could potentially work less well.

I want to be honest about the evidence here: this is theoretical and was only seen with related drugs in a dish, never reported in actual patients. Still, when the whole point of treatment is to fight cancer, it isn't worth gambling. I'd hold off on glucosamine during your valrubicin therapy and let your oncologist or pharmacist make that call.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Yun J, Tomida A, Nagata K, Tsuruo T. Glucose-regulated stresses confer resistance to VP-16 in human cancer cells through a decreased expression of DNA topoisomerase II. Oncol Res 1995;7:583-90.

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

Glucosamine Also Interacts With Other Medications

Glucosamine has 2 major, 12 moderate, 155 minor known drug interactions in our database — the Valrubicin one above is one of them. If you take anything else, check it against the full list below.

Major 2 Moderate 12 Minor 155 No known interaction 2,661 (incl. Valrubicin)
Taking anything else?

Check Another of Your Medications Against Glucosamine

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

From our Q&A

Questions About Glucosamine or Valrubicin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Glucosamine or Valrubicin, 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 Valrubicin

This page covers Glucosamine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Valrubicin page lists 24 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Acerola (moderate), Alpha-lipoic Acid (moderate), Coffee Charcoal (moderate) and European Mandrake (moderate).

By severity: 1 major · 14 moderate · 9 minor.

From our pharmacist’s overview on the Valrubicin page

“Activated charcoal is the supplement I would flag hardest for anyone receiving valrubicin (Valstar), a chemotherapy instilled directly into the bladder for cancer. It carries the only major rating among the 24 ingredients on this page, since charcoal can bind and clear many drugs from the body even when they are not swallowed.”

Reviewed by 2 · Jul 18, 2026

Open the Valrubicin interaction page

One more smart check

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

We hold 1,984 real supplement products containing Glucosamine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Glucosamine. Your product may carry other ingredients that interact with Valrubicin too, on top of Glucosamine — 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 Glucosamine and Valrubicin 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 Glucosamine
Top 10%

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

29 days ago today
Medication Valrubicin
Steady interest

#2,084 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 Glucosamine

What is Glucosamine?

Glucosamine
  • Osteoarthritis
  • Joint pain and stiffness
  • Cartilage support
  • Knee and hip joint health

Glucosamine is a natural compound found in cartilage and joint fluid, and it is one of the most popular supplements for osteoarthritis, especially of the knee. The evidence is mixed, with some people getting modest relief while others get little to no benefit. It is generally well tolerated, but talk to your pharmacist or doctor before starting it, especially if you have a shellfish allergy or diabetes.

Read the full Glucosamine monograph & all interactions
Medication

About Valrubicin Intravesical

What Is Valrubicin Intravesical Used For?

Brand name: Valstar

Valrubicin intravesical solution is used for BCG-refractory carcinoma in situ (CIS) of the urinary bladder. That means early-stage, flat bladder cancer that did not respond to BCG treatment.

It is meant for people who cannot safely have immediate bladder removal surgery (cystectomy) because of unacceptable risk of complications or death.

See full Valrubicin Intravesical drug information
Keep checking

Other Drugs & Glucosamine

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

2Major
12Moderate
155Minor
2,660No known interaction
2 Major 12 Moderate 155 Minor 2,660 No interaction
Major

2 interactions

Moderate

12 interactions

Minor

155 interactions

Showing 60 of 155 minor interactions — see all 155 on the Glucosamine page.

No interaction 2,660 drugs checked — show the list

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

Showing the 60 most looked-up of 2,660 medications checked with no known interaction — see the full Glucosamine list.

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

Can you take Glucosamine with Valrubicin?
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 Glucosamine and Valrubicin 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 Valrubicin and Glucosamine?

Our pharmacists answer your medication & supplement questions — free.

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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.