Water Hemlock Toxic?

Updated 2026-03-06| 2 min read| 4,388 found this helpful

Cicuta maculata

Water Hemlock is fatally toxic to cats, dogs, and horses, with even small ingested amounts potentially leading to rapid death

Cicutoxin, the primary toxic compound, is a powerful central nervous system stimulant that triggers uncontrolled seizures

Immediate emergency veterinary care is critical for any animal suspected of ingesting this plant

FAQ

Is Water Hemlock toxic to Humans?

No human-specific data provided, but ingestion is expected to cause severe neurological and gastrointestinal symptoms, potentially leading to fatality (Severe)

Is Water Hemlock toxic to Cats?

Diarrhea, seizures, tremors, extreme stomach pain, dilated pupils, fever, bloat, respiratory depression, and death (Severe)

Is Water Hemlock toxic to Dogs?

Diarrhea, seizures, tremors, extreme stomach pain, dilated pupils, fever, bloat, respiratory depression, and death (Severe)

Is Water Hemlock toxic to Horses?

Diarrhea, seizures, tremors, extreme stomach pain, dilated pupils, fever, bloat, respiratory depression, and death (Severe)

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Toxicity Details

Humans

Severe

No human-specific data provided, but ingestion is expected to cause severe neurological and gastrointestinal symptoms, potentially leading to fatality

Cats

Severe

Diarrhea, seizures, tremors, extreme stomach pain, dilated pupils, fever, bloat, respiratory depression, and death

Dogs

Severe

Diarrhea, seizures, tremors, extreme stomach pain, dilated pupils, fever, bloat, respiratory depression, and death

Horses

Severe

Diarrhea, seizures, tremors, extreme stomach pain, dilated pupils, fever, bloat, respiratory depression, and death

Toxicity Snapshot

Toxic PartsAll plant parts are toxic, with the roots containing the highest concentration of cicutoxin

Exposure RoutePrimarily ingestion of any plant part, often accidental when mistaken for edible root vegetables like parsnips or carrots

Toxic CompoundsCicutoxin

First Aid & Prevention

First 30 Minutes

• Immediately remove any remaining plant material from the exposed animal's mouth if safe to do so
• Do not induce vomiting unless explicitly instructed by a licensed veterinarian
• Save a sample of the ingested plant and note the exact time of exposure for veterinary reference

Contact Vet Immediately

• Any confirmed or suspected ingestion of any part of Water Hemlock, even if no symptoms are present
• Appearance of seizures, tremors, dilated pupils, or abdominal pain after potential plant exposure
• Signs of respiratory distress, bloat, or sudden fever in animals with access to areas where the plant grows

Prevention

• Remove all Water Hemlock plants from yards, pastures, and other areas accessible to pets, livestock, and children
• Educate household members and livestock handlers to distinguish Water Hemlock from edible Apiaceae family food plants
• Restrict horse and cattle grazing in wet, marshy areas where Water Hemlock is commonly found

Treatment & Prognosis

• Administer activated charcoal to reduce cicutoxin absorption if ingestion occurred within the past 2 hours
• Provide anticonvulsant medication to control seizures, plus IV fluids and respiratory support as clinically needed
• Monitor vital signs and organ function closely for 72 hours post-exposure to manage secondary complications

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Professional Toxicology

Scientific NameCicuta maculata

Aliasescowbane、poison parsnip

Toxicity Grade

HumansSevere

CatsSevere

DogsSevere

HorsesSevere

Target Organs

Central nervous systemGastrointestinal tractRespiratory systemKidneys

Mechanism of Action

• Cicutoxin blocks inhibitory gamma-aminobutyric acid (GABA) receptors in the central nervous system, causing unregulated neuronal activity, severe seizures, and eventual respiratory failure

Other Species Risk (CliniTox)

Information from CliniTox veterinary text.

Cattle: High toxicity risk, ingestion commonly causes fatal seizures and respiratory failure in grazing livestock

Sheep: Moderate to high toxicity risk, with even small ingested amounts leading to severe neurological symptoms

Goats: Moderate toxicity risk, ingestion causes gastrointestinal distress and seizures in severe cases

Confusion Risk

The following plants look similar and may be confused:

Wild Parsnip Pastinaca sativa

Both are Apiaceae family plants with lacy white flower clusters and hollow stems; key difference: Water Hemlock has distinct purple spots/streaks on its stems, while wild parsnip stems are solid green

Queen Anne's Lace Daucus carota

Both produce umbrella-shaped white flower heads and grow in similar sunny, moist habitats; key difference: Water Hemlock lacks the small dark central flower characteristic of Queen Anne's Lace

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Related Toxic Plants

Poison Hemlock

Conium maculatum

Severe, fatal toxicity to humans and most animals

Giant Hogweed

Heracleum mantegazzianum

High, causes severe phototoxic skin burns and systemic toxicity if ingested

Fool's Parsley

Aethusa cynapium

Moderate to High, causes severe gastrointestinal and neurological toxicity in humans and animals

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Data Sources

1. ASPCA Animal Poison Control

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

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