Waterfennel, Water Dropwort Toxic?

Updated 2026-03-06| 2 min read| 1,018 found this helpful

Oenanthe lachanalii C.C.Gmel.

All plant parts (including dried material) contain oenanthotoxin that is not degraded by cooking or drying, so all forms are toxic

Ingestion can cause severe convulsions, paralysis, and rapid death in horses and cattle, with limited fatal risk for sheep

It is easily confused with both non-toxic foraged herbs and other highly toxic Apiaceae species, raising accidental exposure risk

FAQ

Is Waterfennel, Water Dropwort toxic to Humans?

No human-specific symptom data is documented; expected effects include gastrointestinal distress, convulsions, paralysis, and potential fatality if ingested (High)

Is Waterfennel, Water Dropwort toxic to Cats?

No cat-specific toxicity data available; ingestion is suspected to cause toxic reactions including seizures and gastrointestinal distress (Unknown)

Is Waterfennel, Water Dropwort toxic to Dogs?

No dog-specific toxicity data available; ingestion is suspected to cause toxic reactions including seizures and gastrointestinal distress (Unknown)

Is Waterfennel, Water Dropwort toxic to Horses?

Salivation, colic, constipation, dilated pupils, convulsions, unsteady gait, rapid heart rate, rapid breathing, paralysis, death, or diarrhea followed by slow recovery (High)

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Toxicity Details

Humans

High

No human-specific symptom data is documented; expected effects include gastrointestinal distress, convulsions, paralysis, and potential fatality if ingested

Cats

Unknown

No cat-specific toxicity data available; ingestion is suspected to cause toxic reactions including seizures and gastrointestinal distress

Dogs

Unknown

No dog-specific toxicity data available; ingestion is suspected to cause toxic reactions including seizures and gastrointestinal distress

Horses

High

Salivation, colic, constipation, dilated pupils, convulsions, unsteady gait, rapid heart rate, rapid breathing, paralysis, death, or diarrhea followed by slow recovery

Toxicity Snapshot

Toxic PartsEntire plant, including dried plant material

Exposure RouteOral ingestion is the only confirmed exposure route; no dermal or inhalation toxicity data is available

Toxic CompoundsOenanthotoxin (polyacetylene)

First Aid & Prevention

First 30 Minutes

• Induce vomiting only if ingestion occurred within 15 minutes and the affected individual is fully conscious
• Administer activated charcoal at 1-2g per kg of body weight to reduce toxin absorption
• Move the affected individual to a dim, quiet space to minimize triggers for convulsions

Contact Vet Immediately

• If any ingestion of the plant is confirmed or suspected, even if no symptoms are present
• If symptoms including excessive salivation, unsteady gait, convulsions, or breathing difficulty appear
• If the affected individual loses consciousness or experiences continuous seizures

Prevention

• Restrict livestock grazing in wetland or meadow areas where this species is known to grow
• Avoid foraging for wild Apiaceae family herbs, as this plant is easily misidentified as edible varieties
• Remove all identified specimens of this plant from areas accessible to pets and livestock

Treatment & Prognosis

• Perform decontamination procedures including gastric lavage for confirmed recent ingestions
• Administer symptomatic care including anticonvulsants for seizure control, and fluid/electrolyte replacement
• Continuously monitor cardiac and respiratory function until symptoms fully resolve

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Professional Toxicology

Scientific NameOenanthe lachanalii C.C.Gmel.

AliasesLachenal's water fennel、Meadow water fennel、Lachenal's oenanthe

Toxicity Grade

HumansHigh

CatsUnknown

DogsUnknown

HorsesHigh

Target Organs

Central nervous systemGastrointestinal tractCardiovascular systemRespiratory system

Mechanism of Action

• Oenanthotoxin acts as a central nervous system convulsant, disrupting normal neural signaling pathways

• The toxin is heat-stable, so cooking, drying, or processing the plant does not reduce its toxicity

Other Species Risk (CliniTox)

Information from CliniTox veterinary text.

Cattle: Symptoms include salivation, colic, constipation, dilated pupils, convulsions, unsteady gait, rapid heart rate, rapid breathing, paralysis, death, or diarrhea followed by slow recovery

Pig: Symptoms include vomiting, or rapid acute death with no prior visible warning signs

Sheep: Primary reported symptom is diarrhea, with significantly lower risk of fatal outcomes compared to horses and cattle

Confusion Risk

The following plants look similar and may be confused:

Other water dropwort species Other Oenanthe species

Closely related species share nearly identical leaf, flower, and habitat traits; most Oenanthe species are toxic to varying degrees

Cow parsley Anthriscus sylvestris

Shares similar fern-like leaves and white umbel flowers with Oenanthe lachanalii; cow parsley is non-toxic and commonly foraged, leading to frequent misidentification

Poison hemlock Conium maculatum

Both are toxic Apiaceae species sharing the same growth habitat and flower structure; poison hemlock has characteristic purple stem spots absent on Oenanthe lachanalii, and is more acutely toxic

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Related Toxic Plants

Heracleum mantegazzianum

High

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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.

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