Drug & supplement interaction

Slippery Elm + Methylnaltrexone

Methylnaltrexone brand name: Relistor.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Slippery Elm 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

Slippery Elm 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 Slippery Elm 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.

Slippery Elm safety at a glance

Slippery Elm overall Use caution Generally well tolerated for short-term use, but high-quality safety data are limited.
Pregnancy Use caution Not enough reliable safety data; some sources caution against using it during pregnancy.
Breastfeeding Use caution There is too little information on safety while breastfeeding, so caution is advised.

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

Still wondering about combining Methylnaltrexone and Slippery Elm? 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. Slippery Elm has documented interactions with 1 drug class — the most serious being oral drugs (moderate) — 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

Slippery Elm Does Interact With Other Medications

Slippery Elm has 2,022 moderate 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 2,022 No known interaction 808 (incl. Methylnaltrexone)
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.

What to actually watch for

What Slippery Elm Itself Has Been Linked To

This is not an interaction — nothing below involves Methylnaltrexone. It is the side-effect record for Slippery Elm on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Slippery Elm, this list is the first place to look. One entry is worth acting on rather than waiting out — marked below.

  • Hives Worth acting on Additional detail

    “Topically, slippery elm extracts can cause contact dermatitis. The pollen is an allergen (6). Contact dermatitis and urticaria have been reported after exposure to slippery elm or an oleoresin contained in the slippery elm bark.”

    Slippery Elm · Natural Medicines adverse-effect record, reported in dermatitis.

    2 sources cited
    1. 6. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
    2. 75131. Czarnecki D, Nixon R, Bekhor P, and et al. Delayed prolonged contact urticaria from the elm tree. Contact Dermatitis 1993;28:196-197. PubMed
  • A skin rash Additional detail

    Recorded for Slippery Elm in the same Natural Medicines adverse-effect record shown under Hives above.

Everything above comes from the Natural Medicines adverse-effect record for Slippery Elm — expand a row for the licensed statement it rests on. We read the ADVERSE REACTIONS section of Methylnaltrexone’s FDA label too, and the two lists don’t meaningfully overlap — which is why no Methylnaltrexone column appears here.

How to take them

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

At least one FDA label for a product containing Methylnaltrexone says to take it on an empty stomach. Most supplements — Slippery Elm 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 Slippery Elm 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. See the Methylnaltrexone drug page ›

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 Slippery Elm 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. Slippery Elm 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.

Slippery Elm has been studied for:

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

    Slippery Elm for cancer

    Oral slippery elm has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

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

    Slippery Elm for constipation

    Although there has been interest in using oral slippery elm for constipation, there is insufficient reliable information about the clinical effects of slippery elm for this purpose.

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 Slippery Elm for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Slippery Elm or Methylnaltrexone

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 Methylnaltrexone, 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 Methylnaltrexone

This page covers Slippery Elm 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 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. Even though Slippery Elm 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 Slippery Elm 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 Slippery Elm
Top 10%

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

29 days ago today
Medication Methylnaltrexone
Steady interest

#2,432 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 Slippery Elm reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Slippery Elm and Methylnaltrexone records this page draws on were last updated July 11, 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 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.

Ulmus rubra · Ulmaceae · Inner bark · Capsules, tablets, lozenges, powder, tea, throat lozenges, topical pastes

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

Slippery Elm: dosing

There is no official standardized dose for slippery elm. The right amount can vary depending on the form (lozenge, capsule, powder, or tea) and the product.The safest approach is to follow the directions on the product label. When using the powder or capsules, take them with a full glass of water.

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

Read the full Slippery Elm 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 & 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
2,022Moderate
0Minor
807No known interaction
2,022 Moderate 807 No interaction
Moderate

2,022 interactions

Showing 60 of 2,022 moderate interactions — see all 2,022 on the Slippery Elm page.

No interaction 807 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 807 medications checked with no known interaction — see the full Slippery Elm list.

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

Slippery Elm References

The 3 references that drive our Slippery Elm 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. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  3. Czarnecki D, Nixon R, Bekhor P, and et al. Delayed prolonged contact urticaria from the elm tree. Contact Dermatitis 1993;28:196-197. PubMed

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 Slippery Elm and Methylnaltrexone Together: Common Questions

Is it safe to take Slippery Elm with Methylnaltrexone?
We do not list a known interaction between Slippery Elm 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 Slippery Elm 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 Slippery Elm 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 Slippery Elm 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 Slippery Elm in each. That is a conversation for your prescriber, especially if Methylnaltrexone is being adjusted to a target.
How was the Slippery Elm and Methylnaltrexone combination checked?
Interactions in our licensed database are recorded against drug classes. Methylnaltrexone is filed under 1 classification, and Slippery Elm has documented interactions with 1 drug class — 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 Slippery Elm interact with any other medications?
Yes. Slippery Elm has 2,022 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 — Slippery Elm 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

Slippery Elm 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 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Methylnaltrexone 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.