Drug & supplement interaction

American Mistletoe + Methylnaltrexone

Methylnaltrexone brand name: Relistor.

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

We found no known interaction between American Mistletoe 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, and the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

American Mistletoe 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 American Mistletoe 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.

American Mistletoe safety at a glance

American Mistletoe overall Avoid American mistletoe contains toxic compounds and is not recommended for medicinal use.
Pregnancy Likely Unsafe When used orally. American mistletoe is considered an abortifacient. Read the full pregnancy detail
Breastfeeding Likely Unsafe When used orally; avoid using. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Methylnaltrexone and American Mistletoe? 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. American Mistletoe has documented interactions with 2 drug classes — the most serious being antihypertensive drugs (major) and vasodilators (major) — 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

American Mistletoe Does Interact With Other Medications

American Mistletoe has 190 major, known drug interactions in our database — Methylnaltrexone isn’t one of them. If you take anything else, check it against the full list below.

Major 190 No known interaction 2,640 (incl. Methylnaltrexone)
Taking anything else?

Check Another of Your Medications Against American Mistletoe

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

What to actually watch for

No Interaction Found — But Data Suggests American Mistletoe and Methylnaltrexone May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Diarrhea / Vomiting / Nausea Additional detail

    American Mistletoe

    “Evidence on adverse effects related to American mistletoe is limited to retrospective case reviews from poison control centers. Most reports suggest that American mistletoe may be relatively well tolerated at lower doses.”

    American Mistletoe · Natural Medicines adverse-effect record, reported in cardiac arrest.

    “Orally, American mistletoe can cause acute gastroenteritis. Consuming large doses of American mistletoe may cause nausea, vomiting, and diarrhea. Diarrhea and vomiting from ingestion of American mistletoe can lead to dehydration, hypovolemic shock, and cardiovascular collapse (6).”

    American Mistletoe · Natural Medicines adverse-effect record, reported in diarrhea.

    1 source cited
    1. 6. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.

    Methylnaltrexone

    Listed in the ADVERSE REACTIONS section of the FDA label for Methylnaltrexone. Read the label on DailyMed ›

Reported for American Mistletoe but not commonly for Methylnaltrexone: hallucinations, raised blood pressure, a slow heartbeat and dehydration.

Effects for Methylnaltrexone come from the ADVERSE REACTIONS section of its FDA label; effects for American Mistletoe come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

American Mistletoe in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When used orally. American mistletoe is considered an abortifacient.

Lactation Likely Unsafe

When used orally; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

How to take them

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

At least one FDA label for a product containing Methylnaltrexone says to take it on an empty stomach. Most supplements — American Mistletoe 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 American Mistletoe 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 American Mistletoe 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. American Mistletoe 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.

American Mistletoe has been studied for:

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

    American Mistletoe for constipation

    Although there has been interest in using oral American mistletoe for constipation, there is insufficient reliable information about the clinical effects of American mistletoe 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 American Mistletoe 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 American Mistletoe 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

How much people look this up

Where American Mistletoe 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 American Mistletoe
Steady interest

#1,031 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 American Mistletoe reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The American Mistletoe 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 American Mistletoe

What is American Mistletoe?

American Mistletoe
  • Traditional folk remedies
  • Digestive complaints
  • Decorative holiday plant

American mistletoe is a parasitic plant that is best known as a holiday decoration, not a proven medicine. It contains toxins that can harm the heart, gut, and blood vessels, and it has little reliable evidence to support any health use. We do not recommend taking it, and all parts should be kept away from children and pets.

Phoradendron leucarpum · Santalaceae · Leaves, stems, and berries · Rarely used as a supplement; historically as tea or dried plant. Most often seen as a holiday decoration.

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

American Mistletoe: dosing

There is no established safe or effective dose of American mistletoe. Because the plant is toxic and not recommended for medicinal use, no dosing guidance can be given.If you ever see a product containing mistletoe, do not take it without first speaking to a pharmacist or doctor. The safest approach is to avoid using American mistletoe internally altogether.

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

Read the full American Mistletoe 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 & American Mistletoe

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

190Major
0Moderate
0Minor
2,639No known interaction
190 Major 2,639 No interaction
Major

190 interactions

Showing 60 of 190 major interactions — see all 190 on the American Mistletoe page.

No interaction 2,639 drugs checked — show the list

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

Showing the 60 most looked-up of 2,639 medications checked with no known interaction — see the full American Mistletoe list.

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

American Mistletoe References

The 4 references that drive our American Mistletoe 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. Foster S, Tyler VE. Tyler's Honest Herbal, 4th ed., Binghamton, NY: Haworth Herbal Press, 1999. DOI
  4. Moore HW. Mistletoe poisoning: a review of the available literature, and the report of a case of probable fatal poisoning. J S Carolina Med Assoc 1963;59(8):269-271.

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 American Mistletoe and Methylnaltrexone Together: Common Questions

Is it safe to take American Mistletoe with Methylnaltrexone?
We do not list a known interaction between American Mistletoe 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.
Do American Mistletoe and Methylnaltrexone have any of the same side effects?
Yes — our sources link each of them separately to 3 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Should I take American Mistletoe 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 American Mistletoe 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 American Mistletoe 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 American Mistletoe in each. That is a conversation for your prescriber, especially if Methylnaltrexone is being adjusted to a target.
How was the American Mistletoe and Methylnaltrexone combination checked?
Interactions in our licensed database are recorded against drug classes. Methylnaltrexone is filed under 1 classification, and American Mistletoe has documented interactions with 2 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 American Mistletoe interact with any other medications?
Yes. American Mistletoe has 190 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 — American Mistletoe 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

American Mistletoe 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 4 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Methylnaltrexone and American Mistletoe?

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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.