Drug & supplement interaction

American Hellebore + Nicardipine

Nicardipine brand names: Cardene, Cardene SR, Cardene IV.

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

Nicardipine falls into 2 drug categories that American Hellebore can interact with; the most serious is rated major. 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
Interactions2
EvidenceC
What do Severity, Likelihood & Evidence mean?
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Interaction report

American Hellebore and Nicardipine

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

American Hellebore interacts with whole categories of medication. Nicardipine falls into 2 of those categories, so it can interact with American Hellebore in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Major).

Major

Qt Interval-Prolonging Drugs

1 of 2

Why this applies to Nicardipine

Nicardipine 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 pairing American Hellebore and your nicardipine. This isn't about one speeding up or slowing down the other in your liver. Instead, both can affect your heart's electrical timing, what doctors call the QT interval. American Hellebore's alkaloids are heart-toxic and can slow the heart and drop blood pressure dangerously, and they may stretch out that QT interval. Nicardipine itself already relaxes blood vessels and lowers blood pressure.

Stacking these could mean too much of a good thing: lightheadedness, fainting, a very slow or irregular heartbeat, or in rare cases a serious rhythm problem. Honestly, American Hellebore is a poisonous plant that isn't safe for self-care at all. Please talk with your pharmacist or doctor before going anywhere near it.

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

Antihypertensive Drugs

2 of 2

Nicardipine also falls under Antihypertensive Drugs.

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: nicardipine already lowers your blood pressure by relaxing your blood vessels, and it can slow or stress the heart a bit too. American hellebore pushes in the exact same direction. Its toxic alkaloids drop blood pressure, slow the heart rate, and widen blood vessels on their own. Stack the two together and those effects can pile up.

What that can feel like is dizziness, lightheadedness, fainting, a very slow or irregular heartbeat, nausea, and a dangerous drop in blood pressure. This isn't a maybe; the plant is genuinely poisonous even in tiny amounts. Please don't combine them. Talk with your pharmacist or doctor before using any product containing American hellebore.

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 Nicardipine one above is among them. If you take anything else, check it against the full list below.

Major 327 No known interaction 2,503 (incl. Nicardipine)
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.

Everything else you take

See Every Supplement That Interacts With Nicardipine

This page covers American Hellebore only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Nicardipine page lists 243 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Mistletoe (major), Arsenic (major), Cesium (major) and Coleus (major).

By severity: 11 major · 191 moderate · 41 minor.

From our pharmacist’s overview on the Nicardipine page

“Nicardipine (Cardene) works by relaxing blood vessels to bring blood pressure down, so a supplement that shifts how much of the drug reaches your blood, or that moves blood pressure on its own, is worth genuine care rather than a shrug. Grapefruit can raise nicardipine levels enough to intensify its effects, while St.”

Reviewed by 2 · Jul 18, 2026

Open the Nicardipine interaction page

How much people look this up

Where American Hellebore and Nicardipine 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

#1,107 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Nicardipine
Steady interest

#1,664 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 Nicardipine

What Is Nicardipine Used For?

Brand names: Cardene, Cardene SR, Cardene IV

Nicardipine Hydrochloride capsules are used to treat high blood pressure (hypertension) and chronic stable angina (chest pain that comes on with physical effort). The capsules can be used alone or combined with other blood pressure or heart medications.

Intravenous (IV) nicardipine products — including Cardene I.V., Nicardipine Hydrochloride Injection, and Nicardipine Hydrochloride in Sodium Chloride — are used for the short-term treatment of high blood pressure in hospital settings when a patient cannot take oral medication. Once stable, patients are switched to oral therapy.

See full Nicardipine 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 Nicardipine, 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 Nicardipine supplement interactions › Every supplement checked against Nicardipine, ranked by severity Nicardipine 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 Nicardipine Together: Common Questions

Can you take American Hellebore with Nicardipine?
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.
Why are there 2 interactions listed for American Hellebore and Nicardipine?
Nicardipine belongs to more than one drug category, and American Hellebore interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the American Hellebore and Nicardipine 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 Nicardipine 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.