Drug & supplement interaction

Marshmallow + Carmustine

Carmustine brand names: Gliadel, BiCNU, Gliadel Wafer.

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

Marshmallow has a minor interaction with Carmustine. Theoretically, mucilage in marshmallow might impair absorption of oral drugs.

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

Marshmallow and Carmustine

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

Minor

ORAL DRUGS

Why this applies to Carmustine

Carmustine falls under ORAL DRUGS — the group Marshmallow interacts with.

Theoretically, mucilage in marshmallow might impair absorption of oral drugs.
Marshmallow contains mucilage which can affect oral drug absorption. To avoid changes in absorption, take marshmallow 30-60 minutes after oral medications.
Severity Minor 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 thing about this one: the concern with marshmallow is that its slippery mucilage fiber can coat the stomach and gut, which could slow down how well a swallowed pill is absorbed. But carmustine (BiCNU) is given as an IV infusion, and the Gliadel form is a wafer your surgeon places directly into the brain during surgery. Neither one travels through your digestive tract, so marshmallow's gut-coating effect really doesn't have a chance to interfere.

This caution is theoretical and applies to oral medicines, so it doesn't fit how carmustine is actually delivered. Still, since you're being treated for cancer, please run any supplement past your oncology team or pharmacist first, just to keep everything coordinated and safe.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Monographs on the medicinal uses of plant drugs. Exeter, UK: European Scientific Co-op Phytother, 1997.
  2. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  3. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  4. 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

Marshmallow Also Interacts With Other Medications

Marshmallow has 1 moderate, 2,038 minor 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 1 Minor 2,038 No known interaction 791 (incl. Carmustine)
Taking anything else?

Check Another of Your Medications Against Marshmallow

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

Everything else you take

See Every Supplement That Interacts With Carmustine

This page covers Marshmallow 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 Marshmallow as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,622 real supplement products containing Marshmallow, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Marshmallow. Your product may carry other ingredients that interact with Carmustine too, on top of Marshmallow — 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 Marshmallow 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 Marshmallow
Top 10%

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

29 days ago today
Medication Carmustine
Top 25%

#681 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 Marshmallow

What is Marshmallow?

Marshmallow
  • Cough and sore throat
  • Dry mouth and throat irritation
  • Digestive upset and heartburn
  • Skin irritation
  • Soothing inflamed tissue

Marshmallow root is a traditional herb rich in soothing, gel-like fibers called mucilage, which is why it has long been used for coughs, sore throats, and stomach irritation. Evidence for these uses is mostly traditional and preliminary, but it is generally considered gentle and well-tolerated for short-term use. As with any supplement, check with your pharmacist or doctor before using it, especially if you are pregnant, breastfeeding, or taking other medicines.

Read the full Marshmallow 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 & Marshmallow

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

0Major
1Moderate
2,038Minor
790No known interaction
1 Moderate 2,038 Minor 790 No interaction
Moderate

1 interaction

Minor

2,038 interactions

Showing 60 of 2,038 minor interactions — see all 2,038 on the Marshmallow page.

No interaction 790 drugs checked — show the list

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

Showing the 60 most looked-up of 790 medications checked with no known interaction — see the full Marshmallow list.

See the full Marshmallow 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
Marshmallow 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 Marshmallow and Carmustine Together: Common Questions

Can you take Marshmallow with Carmustine?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Marshmallow and Carmustine interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Carmustine and Marshmallow?

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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.