Drug & supplement interaction

Water Hemlock + Obinutuzumab

Obinutuzumab brand name: Gazyva.

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 Water Hemlock and Obinutuzumab 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 label for Obinutuzumab states a food rule worth keeping to, and 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

Water Hemlock and Obinutuzumab

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 Obinutuzumab and Water Hemlock 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.

Water Hemlock safety at a glance

Water Hemlock overall Avoid Water hemlock is deadly poisonous and should never be consumed.
Pregnancy Unsafe When used orally or topically. Water hemlock is toxic; avoid using. Read the full pregnancy detail
Breastfeeding Unsafe When used orally or topically. Water hemlock is toxic; avoid using. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Obinutuzumab and Water Hemlock? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
Keep it in perspective

Water Hemlock Does Interact With Other Medications

Water Hemlock has 1 moderate known drug interaction in our database — Obinutuzumab isn’t one of them. If you take anything else, check it against the full list below.

Moderate 1 No known interaction 2,829 (incl. Obinutuzumab)
Taking anything else?

Check Another of Your Medications Against Water Hemlock

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

What to actually watch for

No Interaction Found — But Data Suggests Water Hemlock and Obinutuzumab 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. One of them is worth acting on rather than waiting out — marked below.

  • Kidney problems Worth acting on Additional detail

    Water Hemlock

    “Water hemlock is a known highly toxic plant and causes a variety of symptoms including vomiting, acute renal failure, marked metabolic acidosis, seizures and convulsions, or unconsciousness that may lead to death.”

    Water Hemlock · Natural Medicines adverse-effect record, reported in epilepsy.

    6 sources cited
    1. 6350. Applefeld JJ, Caplan ES. A case of water hemlock poisoning. JACEP 1979;8:401-3. PubMed
    2. 54716. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Scatizzi, A., De Marco, S., and Smialek, J. E. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephr PubMed
    3. 6351. Carlton BE, Tufts E, Girard DE. Water hemlock poisoning complicated by rhabdomyolysis and renal failure. Clin Toxicol 1979;14:87-92. PubMed
    4. 6348. Knutsen OH, Paszkowski P. New aspects in the treatment of water hemlock poisoning. J Toxicol Clin Toxicol 1984;22:157-66. PubMed
    5. 6346. Starreveld E, Hope E. Cicutoxin poisoning (water hemlock). Neurol 1975;25:730-4. PubMed
    6. 85535. Landers, D., Seppi, K., and Blauer, W. Seizures and death on a white river float trip. Report of water hemlock poisoning. West J.Med. 1985;142(5):637-640. DOI

    “According to case reports, oral ingestion may cause an explosive illness with rhabdomyolysis, marked metabolic acidosis, or acute renal failure.”

    Water Hemlock · Natural Medicines adverse-effect record, reported in muscle breakdown.

    4 sources cited
    1. 54716. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Scatizzi, A., De Marco, S., and Smialek, J. E. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephr PubMed
    2. 6351. Carlton BE, Tufts E, Girard DE. Water hemlock poisoning complicated by rhabdomyolysis and renal failure. Clin Toxicol 1979;14:87-92. PubMed
    3. 6348. Knutsen OH, Paszkowski P. New aspects in the treatment of water hemlock poisoning. J Toxicol Clin Toxicol 1984;22:157-66. PubMed
    4. 6346. Starreveld E, Hope E. Cicutoxin poisoning (water hemlock). Neurol 1975;25:730-4. PubMed

    Obinutuzumab

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

  • Tiredness Additional detail

    Water Hemlock

    “According to case reports, oral ingestion may cause an explosive illness with seizures and convulsions, neurologic lethargy, or unconsciousness that may lead to death.”

    Water Hemlock · Natural Medicines adverse-effect record, reported in epilepsy.

    6 sources cited
    1. 54716. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Scatizzi, A., De Marco, S., and Smialek, J. E. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephr PubMed
    2. 85535. Landers, D., Seppi, K., and Blauer, W. Seizures and death on a white river float trip. Report of water hemlock poisoning. West J.Med. 1985;142(5):637-640. DOI
    3. 6348. Knutsen OH, Paszkowski P. New aspects in the treatment of water hemlock poisoning. J Toxicol Clin Toxicol 1984;22:157-66. PubMed
    4. 6346. Starreveld E, Hope E. Cicutoxin poisoning (water hemlock). Neurol 1975;25:730-4. PubMed
    5. 6350. Applefeld JJ, Caplan ES. A case of water hemlock poisoning. JACEP 1979;8:401-3. PubMed
    6. 85531. Heath, K. B. A fatal case of apparent water hemlock poisoning. Vet.Hum.Toxicol. 2001;43(1):35-36.

    Obinutuzumab

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

Reported for Water Hemlock but not commonly for Obinutuzumab: low blood pressure, stomach pain, severe muscle breakdown and seizures.

Effects for Obinutuzumab come from the ADVERSE REACTIONS section of its FDA label; effects for Water Hemlock 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.

Special populations

Water Hemlock in Pregnancy & Breastfeeding

Pregnancy And Lactation Unsafe

When used orally or topically. Water hemlock is toxic; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

How to take them

Some Obinutuzumab Products Have a Food Rule — Water Hemlock Should Not Break It

At least one FDA label for a product containing Obinutuzumab says to take it on an empty stomach. Most supplements — Water Hemlock included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Obinutuzumab on its own and move Water Hemlock to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Obinutuzumab products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

650–1,000 mg acetaminophen At least 30 minutes before GAZYVA infusion.

From the Dosage and Administration section of the FDA label we read for Obinutuzumab — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

How much people look this up

Where Water Hemlock and Obinutuzumab 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 Water Hemlock
Top half

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

29 days ago today
Medication Obinutuzumab
Steady interest

#2,049 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 Water Hemlock reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Water Hemlock and Obinutuzumab 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 Water Hemlock

What is Water Hemlock?

  • Historically misused in folk practice (not recommended)
  • Sometimes confused with edible wild carrots or parsnips
  • No safe medicinal use

Water hemlock is one of the most poisonous plants in North America and is NOT a safe dietary supplement or herbal remedy. Even small amounts can cause violent seizures and death. Never eat, brew, or take any part of this plant, and seek emergency care immediately if exposure is suspected.

Cicuta maculata · Apiaceae · None — this is a toxic plant, not a usable supplement (roots are the most poisonous part) · Not used as a supplement; sometimes mistaken for edible wild plants

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

Water Hemlock: dosing

There is no safe dose of water hemlock. The only appropriate action with this plant is avoidance and, in case of exposure, emergency care.

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

Read the full Water Hemlock monograph & all interactions
Medication

About Obinutuzumab Injection

What Is Obinutuzumab Injection Used For?

Brand name: Gazyva

Gazyva is used to treat three conditions. For chronic lymphocytic leukemia (CLL), it is given in combination with chlorambucil in patients who have not been treated before. For follicular lymphoma (FL), it is used either with bendamustine (for patients whose disease came back or stopped responding to a rituximab-based regimen) or with chemotherapy (for previously untreated advanced disease) — in both cases followed by Gazyva alone as maintenance therapy.

Gazyva is also approved for active lupus nephritis — a type of kidney inflammation caused by lupus — in adults who are already receiving standard therapy for the condition.

See full Obinutuzumab Injection drug information
Keep checking

Other Drugs & Water Hemlock

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

0Major
1Moderate
0Minor
2,828No known interaction
1 Moderate 2,828 No interaction
Moderate

1 interaction

No interaction 2,828 drugs checked — show the list

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

Showing the 60 most looked-up of 2,828 medications checked with no known interaction — see the full Water Hemlock list.

See the full Water Hemlock interactions page
See every supplement checked against Obinutuzumab, ranked by severity
Evidence & sources

Water Hemlock References

The 8 references that drive our Water Hemlock 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. Starreveld E, Hope E. Cicutoxin poisoning (water hemlock). Neurol 1975;25:730-4. PubMed
  2. Knutsen OH, Paszkowski P. New aspects in the treatment of water hemlock poisoning. J Toxicol Clin Toxicol 1984;22:157-66. PubMed
  3. Anon. Water hemlock poisoning - Maine, 1992. MMWR Morb Mortal Wkly Rep 1994;43:229-31. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/00026056.htm.
  4. Applefeld JJ, Caplan ES. A case of water hemlock poisoning. JACEP 1979;8:401-3. PubMed
  5. Carlton BE, Tufts E, Girard DE. Water hemlock poisoning complicated by rhabdomyolysis and renal failure. Clin Toxicol 1979;14:87-92. PubMed
  6. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Scatizzi, A., De Marco, S., and Smialek, J. E. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephr PubMed
  7. Heath, K. B. A fatal case of apparent water hemlock poisoning. Vet.Hum.Toxicol. 2001;43(1):35-36.
  8. Landers, D., Seppi, K., and Blauer, W. Seizures and death on a white river float trip. Report of water hemlock poisoning. West J.Med. 1985;142(5):637-640. DOI

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 Water Hemlock and Obinutuzumab Together: Common Questions

Is it safe to take Water Hemlock with Obinutuzumab?
We do not list a known interaction between Water Hemlock and Obinutuzumab. 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 Water Hemlock and Obinutuzumab have any of the same side effects?
Yes — our sources link each of them separately to 2 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.
Should I take Water Hemlock and Obinutuzumab at the same time of day?
At least one FDA label for a product containing Obinutuzumab says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Obinutuzumab on its own and move Water Hemlock to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.
Does Water Hemlock interact with any other medications?
Yes. Water Hemlock has 1 documented drug interaction in our database — Obinutuzumab is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.

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

Where next

Keep Exploring

Water Hemlock monograph Uses, safety profile, and every drug interaction in one place Obinutuzumab Injection drug information The full plain-English guide to this medication Obinutuzumab supplement interactions Every supplement checked against Obinutuzumab, 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 8 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Obinutuzumab and Water Hemlock?

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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.