Drug & supplement interaction

American Hellebore + Clonidine

Clonidine brand name: Catapres.

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

American Hellebore has a major interaction with Clonidine. American hellebore can have potent cardiovascular effects due to the toxic steroid ester alkaloids it contains.

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

American Hellebore and Clonidine

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

Major

Antihypertensive Drugs

Why this applies to Clonidine

Clonidine falls under Antihypertensive Drugs — the group American Hellebore interacts with.

American hellebore can have potent cardiovascular effects due to the toxic steroid ester alkaloids it contains. The alkaloids in this plant notably reduce blood pressure even in small doses. Additionally, the alkaloids can exhibit cardiac depressant, bradycardic, and sedative effects. These alkaloids inhibit the inactivation of sodium-ion channels in excitable cells, particularly those regulating cardiac activity. Furthermore, American hellebore's alkaloids induce vasodilation and block beta-adrenergic activity, potentially influencing the effectiveness or side effects of antihypertensive medications (source https://pubmed.ncbi.nlm.nih.gov/5457326/). Patients should exercise caution and consult healthcare professionals before using American hellebore for any reason.
Severity Major Likelihood Likely Evidence A

Well-controlled human studies have demonstrated the likely existence of this interaction.

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

Here's the simple version: clonidine already works by lowering your heart rate and relaxing your blood vessels to bring blood pressure down. American Hellebore pushes in the very same direction, since its alkaloids drop blood pressure, slow the heart, and add a sedative effect. Stack the two together and those actions can pile up.

What that could feel like is dizziness, lightheadedness when you stand up, a very slow pulse, fainting, or feeling unusually drowsy. This isn't a guess, it's a well-documented and serious concern, and Hellebore itself is genuinely poisonous even in small amounts. Please don't take any product with American Hellebore while on clonidine without first talking to your doctor or pharmacist. Honestly, this plant carries real poisoning risk on its own.

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 Clonidine 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. Clonidine)
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 Clonidine

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 Clonidine, 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 Clonidine

This page covers American Hellebore only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Clonidine page lists 138 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Mistletoe (major), Tyramine (major), Adrafinil (moderate) and Agmatine (moderate).

By severity: 4 major · 113 moderate · 21 minor.

From our pharmacist’s overview on the Clonidine page

“American hellebore is the ingredient I would want a clonidine (Catapres) patient to know about first. Its alkaloids lower blood pressure even in small doses and slow the heart, both things clonidine already does, so the combination can drop someone dangerously low.”

Reviewed by 2 · Jul 18, 2026

Open the Clonidine interaction page

How much people look this up

Where American Hellebore and Clonidine 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

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

29 days ago today
Medication Clonidine
Steady interest

#1,473 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 Clonidine

What Is Clonidine Used For?

Brand name: Catapres

Clonidine is used to treat high blood pressure (hypertension). Several products — including Clonidine Hydrochloride tablets, Javadin oral solution, Nexiclon XR extended-release tablets, and Catapres-TTS skin patches — are approved for this use, either alone or combined with other blood pressure medicines.

Extended-release formulations — including Onyda XR oral suspension and clonidine hydrochloride extended-release tablets (such as Kapvay) — are approved to treat ADHD in children and teenagers ages 6 to 17, either on their own or alongside stimulant medications. Separately, clonidine injection products (Duraclon and others) are used alongside opioid pain medicines to treat severe cancer pain that opioids alone cannot control adequately.

See full Clonidine 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 Clonidine, 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
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Pharmacist Counseling Corner

Taking American Hellebore and Clonidine Together: Common Questions

Can you take American Hellebore with Clonidine?
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 Clonidine 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 Clonidine 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.