Drug & supplement interaction

American Hellebore + Atezolizumab

Atezolizumab brand name: Tecentriq.

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 Hellebore and Atezolizumab 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 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 Hellebore and Atezolizumab

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 Atezolizumab and American Hellebore 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 Hellebore safety at a glance

American Hellebore overall Avoid The plant is highly toxic and can cause life-threatening poisoning even at low doses.
Pregnancy Avoid Toxic alkaloids may harm the parent and fetus; do not use.
Breastfeeding Avoid Safety is unknown and the plant is poisonous; avoid use.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Atezolizumab and American Hellebore? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Atezolizumab

Interactions in our licensed database are recorded against drug classes, not just single drug names. Atezolizumab is filed under 2 classifications — antineoplastics, immunosuppressants. American Hellebore has documented interactions with 2 drug classes — the most serious being antihypertensive drugs (major) and qt interval-prolonging drugs (major) — and none of Atezolizumab’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 Hellebore Does Interact With Other Medications

American Hellebore has 328 major, known drug interactions in our database — Atezolizumab isn’t one of them. If you take anything else, check it against the full list below.

Major 328 No known interaction 2,502 (incl. Atezolizumab)
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.

What to actually watch for

No Interaction Found — But Data Suggests American Hellebore and Atezolizumab 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 Hellebore

    “Orally, American hellebore can cause burning sensations of the mouth and pharynx, diarrhea, nausea, and vomiting (17,18,13435,31101,31105,31110,31118,31123,31131,31132).”

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

    6 sources cited
    1. 17. Ellenhorn MJ, et al. Ellenhorn's Medical Toxicology: Diagnoses and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams & Wilkins, 1997.
    2. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
    3. 13435. Zagler B, Zelger A, Salvatore C, et al. Dietary poisoning with Veratrum album--a report of two cases. Wien Klin Wochenschr 2005;117:106-8. PubMed
    4. 31101. Prince, L. A. and Stork, C. M. Prolonged cardiotoxicity from poison lilly (Veratrum viride). Vet.Hum.Toxicol. 2000;42(5):282-285.
    5. 31105. ZUMOFF, B. Temporary atrioventricular conduction disturbance associated with ingestion of Veratrum viride. Am Heart J 1954;47(4):630-633. PubMed
    6. 31110. BRONSKY, D., BERNSTEIN, M., and CHESROW, E. J. Cardiac arrhythmia from Veratrum viride. Geriatrics 1957;12(6):389-393.

    Atezolizumab

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

  • Headache Additional detail

    American Hellebore

    “Orally, American hellebore can cause depressed mental status, headache, lacrimation, salivation, dysphagia, paresthesias, vertigo, blindness, paralysis, and mild convulsions (17,18,13435,31101,31105,31110,31118,31123,31131,31132).”

    American Hellebore · Natural Medicines adverse-effect record, reported in cluster headache.

    6 sources cited
    1. 17. Ellenhorn MJ, et al. Ellenhorn's Medical Toxicology: Diagnoses and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams & Wilkins, 1997.
    2. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
    3. 13435. Zagler B, Zelger A, Salvatore C, et al. Dietary poisoning with Veratrum album--a report of two cases. Wien Klin Wochenschr 2005;117:106-8. PubMed
    4. 31101. Prince, L. A. and Stork, C. M. Prolonged cardiotoxicity from poison lilly (Veratrum viride). Vet.Hum.Toxicol. 2000;42(5):282-285.
    5. 31105. ZUMOFF, B. Temporary atrioventricular conduction disturbance associated with ingestion of Veratrum viride. Am Heart J 1954;47(4):630-633. PubMed
    6. 31110. BRONSKY, D., BERNSTEIN, M., and CHESROW, E. J. Cardiac arrhythmia from Veratrum viride. Geriatrics 1957;12(6):389-393.

    Atezolizumab

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

Reported for American Hellebore but not commonly for Atezolizumab: seizures, a slow heartbeat, low blood pressure and trouble swallowing.

Effects for Atezolizumab come from the ADVERSE REACTIONS section of its FDA label; effects for American Hellebore 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.

Everything else you take

See Every Supplement That Interacts With Atezolizumab

This page covers American Hellebore only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Atezolizumab page lists 54 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Active Hexose Correlated Compound (ahcc) (moderate), Alfalfa (moderate), American Ginseng (moderate), Andrographis (moderate) and Ashwagandha (moderate).

By severity: 52 moderate · 2 minor.

From our pharmacist’s overview on the Atezolizumab page

“Atezolizumab (Tecentriq) is cancer immunotherapy, a drug designed to release the brakes on your own immune system so it can attack tumors. That mechanism explains why nearly every one of the 54 supplements and herbs on this page made the list: 53 are flagged because they appear to stimulate immune activity, based mostly on lab and anim…”

Reviewed by 2 · Jul 18, 2026

Open the Atezolizumab interaction page

How much people look this up

Where American Hellebore and Atezolizumab 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

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

29 days ago today
Medication Atezolizumab
Steady interest

#2,180 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 Hellebore reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The American Hellebore and Atezolizumab records this page draws on were last updated July 10, 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 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.

Veratrum viride · Melanthiaceae · Rhizome and root · Homeopathic preparations (highly diluted); historically tinctures

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

American Hellebore: dosing

There is no established safe dose of American Hellebore for self-care. Historically it was given only by trained practitioners using carefully measured tinctures, and even then poisonings occurred.The only products generally found today are homeopathic, which are extremely diluted. Never make or take a preparation from the raw plant.

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

Read the full American Hellebore monograph & all interactions
Medication

About Atezolizumab Injection

What Is Atezolizumab Injection Used For?

Brand name: Tecentriq

Tecentriq (atezolizumab) is used to treat a range of cancers in adults. It can be used alone or combined with other cancer medicines depending on the cancer type and stage. Approved uses include non-small cell lung cancer (NSCLC) — both after surgery and in metastatic (spread) disease — extensive-stage small cell lung cancer (ES-SCLC), unresectable or metastatic hepatocellular carcinoma (liver cancer), BRAF V600 mutation-positive melanoma, and muscle invasive bladder cancer after surgery.

Tecentriq is also approved — as a single agent — for adult and pediatric patients aged 2 and older with unresectable or metastatic alveolar soft part sarcoma (ASPS), a rare soft tissue cancer. Several of these uses require tumor testing (such as PD-L1 expression or specific gene mutations) before Tecentriq is selected as treatment.

See full Atezolizumab Injection 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.

328Major
0Moderate
0Minor
2,501No known interaction
328 Major 2,501 No interaction
Major

328 interactions

Showing 60 of 328 major interactions — see all 328 on the American Hellebore page.

No interaction 2,501 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 2,501 medications checked with no known interaction — see the full American Hellebore list.

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

American Hellebore References

The 15 references that drive our American Hellebore 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. Ellenhorn MJ, et al. Ellenhorn's Medical Toxicology: Diagnoses and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams & Wilkins, 1997.
  2. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  3. Zagler B, Zelger A, Salvatore C, et al. Dietary poisoning with Veratrum album--a report of two cases. Wien Klin Wochenschr 2005;117:106-8. PubMed
  4. Prince, L. A. and Stork, C. M. Prolonged cardiotoxicity from poison lilly (Veratrum viride). Vet.Hum.Toxicol. 2000;42(5):282-285.
  5. ZUMOFF, B. Temporary atrioventricular conduction disturbance associated with ingestion of Veratrum viride. Am Heart J 1954;47(4):630-633. PubMed
  6. BRONSKY, D., BERNSTEIN, M., and CHESROW, E. J. Cardiac arrhythmia from Veratrum viride. Geriatrics 1957;12(6):389-393.
  7. GOURZIS, J. and BAUER, R. O. Chronic toxicity of a purified extract of Veratrum viride. Proc.Soc.Exp Biol Med 1951;76(4):767-770. DOI
  8. NEWMAN, A. J. Intoxication with Veratrum viride. J Pediatr 1952;40(2):233-234. PubMed
  9. Assali, N. S., Brust, A. A., Garber, S. T., and Ferris, E. B. COMPARATIVE STUDY OF THE EFFECTS OF TETRAETHYL-AMMONIUM CHLORIDE AND VERATRUM VIRIDE ON BLOOD PRESSURE IN NORMAL AND TOXEMIC PREGNANCY. J Clin Invest 1950;29(3):290-296. PubMed
  10. Jaffe, A. M., Gephardt, D., and Courtemanche, L. Poisoning due to ingestion of Veratrum viride (false hellebore). J.Emerg.Med. 1990;8(2):161-167. PubMed
  11. Komchatov, IuN and Nasirov, G. S. [Poisoning by a tincture of false hellebore]. Sud.Med.Ekspert. 1988;31(1):51-52.
  12. Crummett, D., Bronstein, D., and Weaver, Z., III. Accidental Veratrum viride poisoning in three "ramp" foragers. N.C.Med.J. 1985;46(9):469-471.
  13. Garnier, R., Carlier, P., Hoffelt, J., and Savidan, A. [Acute dietary poisoning by white hellebore (Veratrum album L.). Clinical and analytical data. A propos of 5 cases]. Ann.Med.Interne (Paris) 1985;136(2):125-128.
  14. Bechtel LK, Lawrence DT, Haverstick D, et al. Ingestion of false hellebore plants can cross-react with a digoxin clinical chemistry assay. Clin Toxicol (Phila). 2010;48(5):435-42. PubMed
  15. Forrester JD, Price JH, Holstege CP. Intoxication with a ramp (Allium tricocca) mimicker. False hellebore (Veratrum viride) ingestion. Wilderness Environ Med. 2010;21(1):61-3.

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 Hellebore and Atezolizumab Together: Common Questions

Is it safe to take American Hellebore with Atezolizumab?
We do not list a known interaction between American Hellebore and Atezolizumab. 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 Hellebore and Atezolizumab have any of the same side effects?
Yes — our sources link each of them separately to 4 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.
How was the American Hellebore and Atezolizumab combination checked?
Interactions in our licensed database are recorded against drug classes. Atezolizumab is filed under 2 classifications, and American Hellebore has documented interactions with 2 drug classes — none of Atezolizumab'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 Hellebore interact with any other medications?
Yes. American Hellebore has 328 documented drug interactions in our database — Atezolizumab 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 Atezolizumab interact with any supplements?
Yes. Atezolizumab has documented interactions with 54 supplements in our database — American Hellebore is not one of them. The Atezolizumab 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 Hellebore monograph Uses, safety profile, and every drug interaction in one place Atezolizumab Injection drug information The full plain-English guide to this medication Atezolizumab supplement interactions Every supplement checked against Atezolizumab, 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 15 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Atezolizumab 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.