Drug & supplement interaction

Marshmallow + Methylnaltrexone

Methylnaltrexone brand name: Relistor.

No Known Interaction
Medically reviewed by · Updated June 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Marshmallow and Methylnaltrexone in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the label for Methylnaltrexone states a food rule worth keeping to.

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Interaction report

Marshmallow and Methylnaltrexone

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Methylnaltrexone and Marshmallow in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Marshmallow safety at a glance

Marshmallow overall Use caution Generally well tolerated for short-term use, but human safety data are limited.
Pregnancy Avoid Not enough reliable safety information, so it is best avoided during pregnancy.
Breastfeeding Avoid Not enough reliable safety information, so it is best avoided while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Methylnaltrexone and Marshmallow? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Methylnaltrexone

Interactions in our licensed database are recorded against drug classes, not just single drug names. Methylnaltrexone is filed under a single classification — cytochrome p450 2d6 (cyp2d6) inhibitors. Marshmallow has documented interactions with 3 drug classes — the most serious being lithium (moderate), anticoagulant/antiplatelet drugs (minor) and oral drugs (minor) — and none of Methylnaltrexone’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Marshmallow Does Interact With Other Medications

Marshmallow has 1 moderate, 2,039 minor known drug interactions in our database — Methylnaltrexone isn’t one of them. If you take anything else, check it against the full list below.

Moderate 1 Minor 2,039 No known interaction 790 (incl. Methylnaltrexone)
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.

What to actually watch for

What Methylnaltrexone’s Own FDA Label Lists

This is not an interaction — none of it involves Marshmallow. These are the most notable effects listed in the ADVERSE REACTIONS section of Methylnaltrexone’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both.

  • Chills
  • Tremor or shakiness
  • Flushing
  • Bloating or gas
  • Sweating
  • Anxiety or restlessness
  • Muscle pain
  • Stomach upset
  • Constipation
  • Stomach pain

Showing the 10 most notable of 15 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Methylnaltrexone. Read the label on DailyMed › Marshmallow’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Marshmallow side to compare — that is a limit of the record, not a statement that Marshmallow has no side effects.

How to take them

Some Methylnaltrexone Products Have a Food Rule — Marshmallow Should Not Break It

At least one FDA label for a product containing Methylnaltrexone says to take it on an empty stomach. Most supplements — Marshmallow included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Methylnaltrexone on its own and move Marshmallow to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Methylnaltrexone products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

o In patients with chronic non-cancer pain and OIC, take RELISTOR tablets with water on an empty stomach at least 30 minutes before the first meal of the day.

From the Dosage and Administration section of the FDA label we read for Methylnaltrexone — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

Overlapping uses

What Methylnaltrexone Is Prescribed For, and What Marshmallow Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Methylnaltrexone is a prescription medicine with approved uses on its FDA label. Marshmallow is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Methylnaltrexone is prescribed for: Methylnaltrexone, sold as Relistor, treats opioid-induced constipation (OIC) — constipation caused by opioid pain medications. Both Relistor tablets and Relistor injection are approved for adults with chronic non-cancer pain, including those with pain related to a prior cancer or its treatment who do not need frequent opioid dose increases. Relistor injection is also approved for adults with advanced illness or active cancer pain who require increasing opioid doses as part of palliative care.

Marshmallow has been studied for:

  • Constipation studied, not established Marshmallow has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Marshmallow for constipation

    Although there is interest in using oral marshmallow for constipation, there is insufficient reliable information about the clinical effects of marshmallow for this condition.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Methylnaltrexone on your own; if you are taking Marshmallow for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

Everything else you take

See Every Supplement That Interacts With Methylnaltrexone

This page covers Marshmallow only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Methylnaltrexone page lists 3 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Fever Bark (moderate), Iboga (moderate) and Yohimbe (moderate).

By severity: 3 moderate.

From our pharmacist’s overview on the Methylnaltrexone page

“If you take methylnaltrexone (Relistor) for opioid-induced constipation, the supplement list to know is short: three ingredients, all rated moderate, none major. Yohimbe, fever bark, and iboga are all cleared by the same liver enzyme, CYP2D6, and methylnaltrexone can slow that enzyme, letting their active compounds build up in your blood.”

Reviewed by 2 · Jul 18, 2026

Open the Methylnaltrexone 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. Even though Marshmallow itself has no known interaction with Methylnaltrexone, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Marshmallow and Methylnaltrexone 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%

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

29 days ago today
Medication Methylnaltrexone
Steady interest

#2,793 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Marshmallow reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Marshmallow and Methylnaltrexone records this page draws on were last updated June 22, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
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.

Althaea officinalis · Malvaceae · Root and leaves · Tea, capsules, tinctures, syrups, lozenges, dried root, topical creams

An interaction check asks whether these two react with each other — it does not ask whether Marshmallow is a good idea for someone in your situation. Here is what our Marshmallow record says about it on its own.

Marshmallow: dosing

There is no official, standardized dose for marshmallow. The right amount depends on the form (tea, capsule, syrup, lozenge, or tincture) and the specific product.The safest approach is to follow the directions on the product label and not exceed the recommended amount. For teas, the dried root is often steeped in water; for other forms, the manufacturer's instructions should guide you.When taking marshmallow as a capsule or tincture, it is often recommended to drink plenty of water.

From our Marshmallow monograph — the full record covers uses, side effects and every documented interaction.

Read the full Marshmallow monograph & all interactions
Medication

About Methylnaltrexone

What Is Methylnaltrexone Used For?

Brand name: Relistor

Methylnaltrexone, sold as Relistor, treats opioid-induced constipation (OIC) — constipation caused by opioid pain medications. Both Relistor tablets and Relistor injection are approved for adults with chronic non-cancer pain, including those with pain related to a prior cancer or its treatment who do not need frequent opioid dose increases.

Relistor injection is also approved for adults with advanced illness or active cancer pain who require increasing opioid doses as part of palliative care.

See full Methylnaltrexone 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
2,039Minor
789No known interaction
1 Moderate 2,039 Minor 789 No interaction
Moderate

1 interaction

Minor

2,039 interactions

Showing 60 of 2,039 minor interactions — see all 2,039 on the Marshmallow page.

No interaction 789 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 789 medications checked with no known interaction — see the full Marshmallow list.

See the full Marshmallow interactions page
See every supplement checked against Methylnaltrexone, ranked by severity
Evidence & sources

Marshmallow References

The 5 references that drive our Marshmallow monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  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.
  5. 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.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Marshmallow and Methylnaltrexone Together: Common Questions

Is it safe to take Marshmallow with Methylnaltrexone?
We do not list a known interaction between Marshmallow and Methylnaltrexone. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Should I take Marshmallow and Methylnaltrexone at the same time of day?
At least one FDA label for a product containing Methylnaltrexone says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Methylnaltrexone on its own and move Marshmallow to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.
Are Marshmallow and Methylnaltrexone used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Marshmallow in each. That is a conversation for your prescriber, especially if Methylnaltrexone is being adjusted to a target.
How was the Marshmallow and Methylnaltrexone combination checked?
Interactions in our licensed database are recorded against drug classes. Methylnaltrexone is filed under 1 classification, and Marshmallow has documented interactions with 3 drug classes — none of Methylnaltrexone's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Marshmallow interact with any other medications?
Yes. Marshmallow has 2,040 documented drug interactions in our database — Methylnaltrexone is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Methylnaltrexone interact with any supplements?
Yes. Methylnaltrexone has documented interactions with 3 supplements in our database — Marshmallow is not one of them. The Methylnaltrexone interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Marshmallow monograph Uses, safety profile, and every drug interaction in one place Methylnaltrexone drug information The full plain-English guide to this medication Methylnaltrexone supplement interactions Every supplement checked against Methylnaltrexone, 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 References The 5 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Methylnaltrexone 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.