Water-hemlock Toxic?

Updated 2026-03-06| 2 min read| 3,389 found this helpful

All plant parts are highly toxic, particularly rootstock and stems, with highest toxin levels in late autumn; toxins are not inactivated by drying.

Ingestion can cause severe symptoms including violent convulsions, with death possible within 15 minutes due to respiratory paralysis.

Do not administer neuroleptics to affected individuals during the convulsion stage of poisoning.

FAQ

Is Water-hemlock toxic to Humans?

Salivation, agitation, incoordination, violent convulsions, muscle weakness, hyperthermia, dilated pupils, teeth grinding, frequent urination/defecation, difficulty breathing, sudden death (possible within 15 minutes) due to respiratory paralysis (Severe)

Is Water-hemlock toxic to Cats?

Limited species-specific data available; expected clinical signs include salivation, agitation, convulsions, muscle weakness, respiratory distress and potential rapid death following ingestion (Severe)

Is Water-hemlock toxic to Dogs?

Is Water-hemlock toxic to Horses?

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Toxicity Details

Humans

Severe

Cats

Severe

Limited species-specific data available; expected clinical signs include salivation, agitation, convulsions, muscle weakness, respiratory distress and potential rapid death following ingestion

Dogs

Severe

Limited species-specific data available; expected clinical signs include salivation, agitation, convulsions, muscle weakness, respiratory distress and potential rapid death following ingestion

Horses

Severe

Limited species-specific data available; expected clinical signs include salivation, agitation, convulsions, muscle weakness, respiratory distress and potential rapid death following ingestion

Toxicity Snapshot

Toxic PartsAll plant parts, particularly rootstock and stems; highest toxin concentration occurs in late autumn. Toxicity remains intact even after drying.

Exposure RoutePrimary exposure route is ingestion; accidental consumption of roots misidentified as edible root vegetables is the most common cause of poisoning

Toxic CompoundsCicutoxin; Cicutol

First Aid & Prevention

First 30 Minutes

• If ingested, induce vomiting only if the affected individual is conscious and not experiencing convulsions
• Administer activated charcoal as soon as possible to absorb remaining unprocessed toxins
• Move the affected individual to a quiet, dimly lit area to minimize stimulation that can trigger convulsions

Contact Vet Immediately

• Any confirmed or suspected ingestion of any part of water-hemlock, even if no symptoms have appeared yet
• Onset of any poisoning symptoms including salivation, convulsions, incoordination, or difficulty breathing
• If the affected individual loses consciousness or shows signs of respiratory distress

Prevention

• Confirm plant identification before foraging for wild root vegetables like parsnips or celery root
• Remove water-hemlock plants from areas accessible to livestock, pets, and young children
• Never consume any part of a plant suspected to be water-hemlock, even if it has been dried

Treatment & Prognosis

• Perform decontamination via gastric lavage and activated charcoal administration if ingestion occurred recently
• Provide symptomatic therapy including convulsion control with appropriate anticonvulsants; do not use neuroleptics during the convulsive stage
• Closely monitor and support respiratory function to prevent respiratory failure, the leading cause of death from this poisoning

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Professional Toxicology

Scientific NameCicuta virosa L.

AliasesCow bane、Wasserschierling、Giftiger Wasserschierling、Gift-Wasserschierling、Borstenkraut、Sumpfgift、Wüterich、Kuhtod、Barzenkraut、Parzenkraut、Berstekraut、Wütherich Scherte、Ciguë aquatique、Ciguë vireuse、Ciguë des marais、Persil des chats、Persil des marais、Cicuta acquatica

Toxicity Grade

HumansSevere

CatsSevere

DogsSevere

HorsesSevere

Target Organs

Central nervous systemRespiratory systemGastrointestinal tract

Mechanism of Action

• Cicutoxin acts as a central nervous system stimulant, blocking inhibitory neurotransmission to trigger severe convulsions

• Toxins disrupt respiratory muscle function, leading to progressive paralysis and fatal respiratory failure

Other Species Risk (CliniTox)

Information from CliniTox veterinary text.

Cattle: At high risk of poisoning; develop characteristic tympany (bloat) in addition to general neurological and respiratory symptoms, with rapid death possible

General livestock: Ingestion of plant material growing in wet pastures can cause mass poisoning events with high mortality rates

Confusion Risk

The following plants look similar and may be confused:

Wild celery Apium graveolens

Water-hemlock roots are visually similar to wild celery roots; key difference is water-hemlock has thick, hollow, chambered rootstocks that exude yellow oily sap when cut

Wild parsnip Pastinaca sativa

Water-hemlock roots are often misidentified as wild parsnip roots; water-hemlock has a characteristic unpleasant parsnip-like odor and segmented root structure unlike solid parsnip roots

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Related Toxic Plants

Heracleum mantegazzianum

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Data Sources

1. CliniTox (Universität Zürich)

This information is for reference only and does not constitute medical advice. If ingestion or poisoning is suspected, seek medical or veterinary attention immediately.