Drug & supplement interaction

American Mistletoe + Riociguat

Riociguat brand name: Adempas.

Major Interaction
Medically reviewed by · Updated February 2024
The bottom line Major

American Mistletoe has a major interaction with Riociguat. American mistletoe contains phoratoxin, a compound toxic to humans that induces smooth muscle contraction and vasoconstriction, potentially increasing blood pressure and heart rate.

Read the full interaction report
SeverityMajor
LikelihoodProbable
EvidenceC
What do Severity, Likelihood & Evidence mean?
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Interaction report

American Mistletoe and Riociguat

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

Major

Antihypertensive Drugs

Why this applies to Riociguat

Riociguat falls under Antihypertensive Drugs — the group American Mistletoe interacts with.

American mistletoe contains phoratoxin, a compound toxic to humans that induces smooth muscle contraction and vasoconstriction, potentially increasing blood pressure and heart rate. Case reports of cardiotoxicity have been documented with American mistletoe, and it should not be used with antihypertensive drugs or by individuals with cardiac conditions. American mistletoe is uncommon in dietary supplements, and formulations containing it are generally homeopathic. European mistletoe, which lacks phoratoxin, is more commonly used.
Severity Major Likelihood Probable Evidence C

Interaction 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..

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

Here's the concern with pairing American mistletoe and Adempas (riociguat). Your riociguat is doing a very specific job: it relaxes and widens the blood vessels in your lungs to bring that pressure down. American mistletoe pulls in the opposite direction. It contains a toxin called phoratoxin that can tighten blood vessels and stir up the heart, which may push blood pressure and heart rate up and work against the very thing your medicine is trying to fix.

This isn't about how riociguat is broken down, it's about two opposite effects colliding. Riociguat can already cause low blood pressure and dizziness, so adding an unpredictable, toxic plant on top is a poor combination. The good news: real mistletoe in supplements is rare. Please check with your pharmacist or doctor before using anything containing it.

Contact Dr. Brian directly if you have additional questions on this interaction

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

American Mistletoe Also Interacts With Other Medications

American Mistletoe has 189 major, known drug interactions in our database — the Riociguat one above is one of them. If you take anything else, check it against the full list below.

Major 189 No known interaction 2,641 (incl. Riociguat)
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.

Everything else you take

See Every Supplement That Interacts With Riociguat

This page covers American Mistletoe only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Riociguat page lists 230 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 6 major · 187 moderate · 37 minor.

From our pharmacist’s overview on the Riociguat page

“Riociguat (Adempas) works by relaxing the blood vessels in your lungs, which also lowers blood pressure, so I read this list of 230 supplements and herbs with real concern, and the six rated major are what to understand first. Grapefruit can push riociguat levels up and intensify its effect, while St.”

Reviewed by 2 · Jul 18, 2026

Open the Riociguat interaction page

How much people look this up

Where American Mistletoe and Riociguat 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

#1,249 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Riociguat
Steady interest

#1,544 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 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.

Read the full American Mistletoe monograph & all interactions
Medication

About Riociguat

What Is Riociguat Used For?

Brand name: Adempas

Riociguat tablets — sold under the brand names Adempas and Riociguat — are approved for adults with two types of high blood pressure in the lungs. The first is chronic thromboembolic pulmonary hypertension (CTEPH), a condition caused by blood clots that have blocked or narrowed the arteries in the lungs. Riociguat is used when surgery has not fully fixed the problem, or when surgery is not an option.

The second is pulmonary arterial hypertension (PAH), a progressive disease where the arteries in the lungs become stiff and narrowed. In PAH, riociguat helps improve exercise ability, functional class (how well you can get around day-to-day), and slows disease worsening. It can be used alone or combined with other PAH medicines called endothelin receptor antagonists or prostanoids.

See full Riociguat 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.

189Major
0Moderate
0Minor
2,640No known interaction
189 Major 2,640 No interaction
Major

189 interactions

Showing 60 of 189 major interactions — see all 189 on the American Mistletoe page.

No interaction 2,640 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 2,640 medications checked with no known interaction — see the full American Mistletoe list.

See the full American Mistletoe interactions page
See every supplement checked against Riociguat, 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
American Mistletoe monograph › Uses, safety, and every drug interaction in one place Riociguat supplement interactions › Every supplement checked against Riociguat, ranked by severity Riociguat 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 American Mistletoe and Riociguat Together: Common Questions

Can you take American Mistletoe with Riociguat?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the American Mistletoe and Riociguat interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

Still Have a Question About Riociguat 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.