Drug & supplement interaction

Slippery Elm + Carmustine

Carmustine brand names: Gliadel, BiCNU, Gliadel Wafer.

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

Slippery Elm has a moderate interaction with Carmustine. Theoretically, slippery elm may slow the absorption and reduce serum levels of oral drugs.

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

Slippery Elm and Carmustine

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

Moderate

ORAL DRUGS

Why this applies to Carmustine

Carmustine falls under ORAL DRUGS — the group Slippery Elm interacts with.

Theoretically, slippery elm may slow the absorption and reduce serum levels of oral drugs.
Slippery elm inner bark contains mucilage, which may interfere with the absorption of orally administered 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

Here's a wrinkle worth mentioning: the interaction we have on file is about oral medicines, and carmustine (BiCNU) is given as an infusion through your vein, while the Gliadel wafer is placed directly in the brain during surgery. Slippery elm works by forming a slick gel that coats your gut, which can slow down how much of a swallowed pill gets absorbed. Since carmustine doesn't go through your stomach, that gel-in-the-gut effect really doesn't apply here.

So for this particular drug, I wouldn't expect slippery elm to weaken your treatment through that absorption mechanism. Still, anything you take during chemo deserves a quick check. Please run slippery elm by your oncology team or pharmacist before using it, just to be safe.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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

Slippery Elm Also Interacts With Other Medications

Slippery Elm has 2,021 moderate known drug interactions in our database — the Carmustine one above is one of them. If you take anything else, check it against the full list below.

Moderate 2,021 No known interaction 809 (incl. Carmustine)
Taking anything else?

Check Another of Your Medications Against Slippery Elm

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

From our Q&A

Questions About Slippery Elm or Carmustine

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

This page covers Slippery Elm only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Carmustine 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), Coenzyme Q10 (moderate) and Coffee Charcoal (moderate).

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

From our pharmacist’s overview on the Carmustine page

“Activated charcoal is the entry to understand first. It holds the only major rating among the 24 ingredients on file for carmustine, and because it can trap drugs that recirculate through the gut, it may lower carmustine levels even when the chemotherapy arrives by IV or as an implanted Gliadel wafer.”

Reviewed by 2 · Jul 18, 2026

Open the Carmustine interaction page

One more smart check

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

We hold 1,490 real supplement products containing Slippery Elm, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Slippery Elm. Your product may carry other ingredients that interact with Carmustine too, on top of Slippery Elm — 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 Slippery Elm and Carmustine 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 Slippery Elm
Top 10%

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

29 days ago today
Medication Carmustine
Top half

#731 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 Slippery Elm

What is Slippery Elm?

Slippery Elm
  • Sore throat and cough
  • Heartburn and acid reflux
  • Digestive upset and IBS
  • Skin irritation (topical)
  • Constipation or diarrhea

Slippery elm is a traditional herbal remedy made from the inner bark of a North American elm tree, used mainly to soothe sore throats and irritated digestive tracts. Its mucilage can coat and calm mucous membranes, but solid human evidence for most uses is limited. It is generally considered low-risk for short-term use, but you should still check with your pharmacist or doctor first.

Read the full Slippery Elm monograph & all interactions
Medication

About Carmustine

What Is Carmustine Used For?

Brand names: Gliadel, BiCNU, Gliadel Wafer

Carmustine injection is used as palliative therapy — either alone or combined with other chemotherapy drugs — for several brain tumors, including glioblastoma, brainstem glioma, medulloblastoma, astrocytoma, ependymoma, and metastatic brain tumors. It is also used for multiple myeloma (in combination with prednisone), and for relapsed or refractory Hodgkin's lymphoma and Non-Hodgkin's lymphomas (in combination with other approved drugs).

Gliadel — a dissolving wafer form of carmustine placed directly into the brain during surgery — is specifically indicated for newly diagnosed high-grade glioma (as an addition to surgery and radiation) and for recurrent glioblastoma (as an addition to surgery).

See full Carmustine drug information
Keep checking

Other Drugs & Slippery Elm

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

0Major
2,021Moderate
0Minor
808No known interaction
2,021 Moderate 808 No interaction
Moderate

2,021 interactions

Showing 60 of 2,021 moderate interactions — see all 2,021 on the Slippery Elm page.

No interaction 808 drugs checked — show the list

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

Showing the 60 most looked-up of 808 medications checked with no known interaction — see the full Slippery Elm list.

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

Can you take Slippery Elm with Carmustine?
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 Slippery Elm and Carmustine 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 Carmustine and Slippery Elm?

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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.