Drug & supplement interaction

American Hellebore + Tizanidine

Tizanidine brand names: Zanaflex, Ontralfy.

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

American Hellebore has a major interaction with Tizanidine. American hellebore, also known as Veratrum viride, contains alkaloids that can potentially prolong the QT interval on an electrocardiogram (ECG).

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

American Hellebore and Tizanidine

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

Major

Qt Interval-Prolonging Drugs

Why this applies to Tizanidine

Tizanidine falls under Qt Interval-Prolonging Drugs — the group American Hellebore interacts with.

American hellebore, also known as Veratrum viride, contains alkaloids that can potentially prolong the QT interval on an electrocardiogram (ECG). This effect is similar to that of certain medications known as QT-prolonging drugs, which can increase the risk of a serious heart rhythm disorder called torsades de pointes (source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4728534/). Combining American hellebore with other drugs that cause QT-prolongation can increase the risk of adverse effects.
Severity Major Likelihood Possible Evidence C

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 concern with putting these two together. American Hellebore is a genuinely toxic plant, and its alkaloids can mess with your heart's electrical timing in a way that may stretch out the QT interval on an ECG. Tizanidine can also lower your heart rate and blood pressure, and is grouped among medicines that may affect that same heart rhythm timing. Stack the two and you raise the odds of feeling very dizzy, faint, weak, or developing a dangerous irregular heartbeat called torsades de pointes.

Honestly, the bigger worry here is the Hellebore itself, which isn't a safe supplement to take at all. The rhythm evidence is moderate, but the plant's toxicity is real. Please don't combine these without talking to your pharmacist or doctor first.

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 Hellebore Also Interacts With Other Medications

American Hellebore has 327 major, known drug interactions in our database — the Tizanidine one above is one of them. If you take anything else, check it against the full list below.

Major 327 No known interaction 2,503 (incl. Tizanidine)
Taking anything else?

Check Another of Your Medications Against American Hellebore

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

From our Q&A

Questions About American Hellebore or Tizanidine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers American Hellebore or Tizanidine, 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 Tizanidine

This page covers American Hellebore only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tizanidine page lists 143 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Arsenic (major), Beer (major), Cesium (major) and Ephedra (major).

By severity: 11 major · 101 moderate · 31 minor.

Open the Tizanidine interaction page

How much people look this up

Where American Hellebore and Tizanidine 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 Hellebore
Steady interest

#1,077 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Tizanidine
Steady interest

#1,815 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 Hellebore

What is American Hellebore?

American Hellebore
  • High blood pressure
  • Slowing heart rate
  • Toxemia of pregnancy (historical)
  • Convulsions (historical)
  • Pain relief (traditional)

American Hellebore (Veratrum viride) is a highly poisonous plant whose root contains toxic alkaloids that can cause dangerous drops in heart rate and blood pressure, even in small amounts. It is not a safe self-care supplement, and any non-homeopathic product carries a serious risk of poisoning. Do not use it without medical supervision, and talk to a pharmacist or doctor before considering any product that contains it.

Read the full American Hellebore monograph & all interactions
Medication

About Tizanidine

What Is Tizanidine Used For?

Brand names: Zanaflex, Ontralfy

Tizanidine — available as tablets, capsules, and as the oral solution Ontralfy — is used to manage spasticity (abnormal muscle stiffness or spasms). Because it works for a relatively short window of time, it is typically scheduled around the activities when spasm relief matters most.

Ontralfy (oral solution) and Zanaflex capsules are specifically indicated for the treatment of spasticity in adults. Other tizanidine tablets and capsules are indicated for the management of spasticity more broadly.

See full Tizanidine drug information
Keep checking

Other Drugs & American Hellebore

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

327Major
0Moderate
0Minor
2,502No known interaction
327 Major 2,502 No interaction
Major

327 interactions

Showing 60 of 327 major interactions — see all 327 on the American Hellebore page.

No interaction 2,502 drugs checked — show the list

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

Showing the 60 most looked-up of 2,502 medications checked with no known interaction — see the full American Hellebore list.

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

Can you take American Hellebore with Tizanidine?
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 Hellebore and Tizanidine 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 Tizanidine and American Hellebore?

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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.