Drug & supplement interaction

Marshmallow + Selumetinib Sulfate

Selumetinib Sulfate brand name: Koselugo.

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

Selumetinib Sulfate falls into 2 drug categories that Marshmallow can interact with; the most serious is rated minor. Theoretically, mucilage in marshmallow might impair absorption of oral drugs.

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

Marshmallow and Selumetinib Sulfate

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

Why Are There 2 Interactions?

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

Minor

ORAL DRUGS

1 of 2

Why this applies to Selumetinib Sulfate

Selumetinib Sulfate 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 gist with marshmallow and Koselugo (selumetinib). Marshmallow root is loaded with mucilage, a slippery fiber that swells into a gel in your gut. The theory is that this gel could form a coating that keeps an oral medicine from being fully absorbed. If that happened with selumetinib, your child might get a little less of the dose into the bloodstream, which could mean it doesn't work as well against the tumors.

I want to be clear that this is theoretical, based on how the fiber behaves rather than real cases, so it may not amount to much. Still, a simple fix helps: separate the two by taking marshmallow 30 to 60 minutes after the selumetinib dose. Since this is a cancer-type therapy with strict timing and food rules, please run any supplement past your oncology team or pharmacist first.

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.
Minor

ANTICOAGULANT/ANTIPLATELET DRUGS

2 of 2

Selumetinib Sulfate also falls under ANTICOAGULANT/ANTIPLATELET DRUGS.

Theoretically, marshmallow flower might have antiplatelet effects.
Animal research suggests that marshmallow flower extract has antiplatelet effects. However, the root and leaf of marshmallow, not the flower, are the plant parts most commonly found in dietary supplements. Theoretically, use of marshmallow flower with anticoagulant/antiplatelet drugs can have additive effects, and might increase the risk for bleeding in some patients.
Severity Minor Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

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

Here's the honest picture with marshmallow and Koselugo (selumetinib). The interaction on file is really about bleeding risk, and it comes from very early animal work suggesting marshmallow flower might have a mild blood-thinning (antiplatelet) effect. Most supplements use marshmallow root or leaf, not the flower, so this concern is largely theoretical and considered unlikely to cause problems.

Selumetinib itself isn't a blood thinner, but it can sometimes lower platelet counts or cause bleeding-type side effects on its own. So in theory, stacking a mild antiplatelet herb on top could add up and raise bleeding risk a little (think easy bruising, nosebleeds, or bleeding gums). The evidence here is weak, so don't be alarmed, but since selumetinib is a serious cancer-type medicine, please run any marshmallow product past your child's oncology team or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Hage-Sleiman R, Mroueh M, Daher CF. Pharmacological evaluation of aqueous extract of Althaea officinalis flower grown in Lebanon. Pharm Biol 2011;49(3):327-33.

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 Selumetinib Sulfate one above is among them. If you take anything else, check it against the full list below.

Moderate 1 Minor 2,038 No known interaction 791 (incl. Selumetinib Sulfate)
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 Selumetinib Sulfate

This page covers Marshmallow only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Selumetinib Sulfate page lists 282 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Danshen (major), Grapefruit (major), Piracetam (major) and St. John's Wort (major).

By severity: 5 major · 236 moderate · 41 minor.

Open the Selumetinib Sulfate 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 Selumetinib Sulfate 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 Selumetinib Sulfate 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%

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

29 days ago today
Medication Selumetinib Sulfate
Steady interest

#2,178 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 Selumetinib

What Is Selumetinib Used For?

Brand name: Koselugo

Koselugo (selumetinib) is approved for adults and children 1 year of age and older who have neurofibromatosis type 1 (NF1) — a genetic condition that causes tumors to grow on nerve tissue — when they also have symptomatic, inoperable plexiform neurofibromas (large, deep nerve tumors that cannot be surgically removed and are causing problems).

Both the Koselugo capsule and Koselugo oral granule formulations are approved for this use. The oral granule form is intended for patients who have difficulty swallowing whole capsules.

See full Selumetinib 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 Selumetinib Sulfate, 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 Selumetinib Sulfate supplement interactions › Every supplement checked against Selumetinib Sulfate, ranked by severity Selumetinib 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 Selumetinib Sulfate Together: Common Questions

Can you take Marshmallow with Selumetinib Sulfate?
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.
Why are there 2 interactions listed for Marshmallow and Selumetinib Sulfate?
Selumetinib Sulfate belongs to more than one drug category, and Marshmallow 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 Marshmallow and Selumetinib Sulfate 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 Selumetinib Sulfate 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.