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Is Water Hemlock Toxic to Cats?

☠️ ToxicSeverity: Severe
✅ Cross-checked against veterinary poison-control guidance · Oct 2026 audit
⚠️ Educational info only. If your pet just chewed something and looks unwell, skip the reading and call your vet or Pet Poison Helpline (US): (855) 764-7661.
Yes — water hemlock is among the most poisonous plants in North America, and it is severely toxic to cats. Cicutoxin triggers violent seizures that can kill within hours.

Also known as: Cowbane, Beaver Poison, Musquash Root, Cicuta maculata · Cicuta maculata

What makes it toxic

Cicutoxin, a potent neurotoxin concentrated in the roots and root sap but present throughout the plant. It disrupts nerve signaling in the brain, producing uncontrollable seizure activity.

Warning signs to watch for

Rapid onset within 15–60 minutes: drooling, vomiting, dilated pupils, then violent convulsions, muscle rigidity, racing heart and respiratory failure. Death can occur from a small amount.

What to do if your cat eats it

This is the top-tier emergency. Go to a veterinary ER immediately with any plant material — do not wait for symptoms. Seizure control and respiratory support must start fast to save the cat.

Common questions

Why is water hemlock so much worse than poison hemlock?

Poison hemlock kills by gradual paralysis; water hemlock kills by explosive seizures. Cicutoxin acts at tiny doses, and a bite of the root has killed livestock within hours.

My cat only chewed a leaf near a pond — could that be water hemlock?

If the plant is a wetland umbel with divided leaves and a root that smells like parsnip, assume yes and go to the ER. Root sap is the most concentrated, but no part is safe.

More plants checked for cats

Pothos☠️ ToxicYes, pothos is toxic to cats. Chewing the leaves or vines releases sharp calcium oxalate crystalAloe Vera⚠️ Mildly ToxicAloe vera is mildly to moderately toxic to cats. The gel is famously soothing for human skin, buSpider Plant✅ Non-ToxicNo, spider plants are non-toxic to cats. They are one of the best houseplants for homes with curEaster Lily☠️ ToxicYes — and this is one of the most dangerous plants a cat can meet. Every part of an Easter lily,Sago Palm☠️ ToxicYes — sago palm is severely toxic to cats and among the deadliest houseplants. Every part contaiBoston Fern✅ Non-ToxicNo, Boston ferns are non-toxic to cats — a classic choice for plant-loving cat households.

This page is general educational information, not a substitute for professional veterinary advice. Every pet is different — if your animal ate something concerning, contact your veterinarian or a pet poison hotline right away. Checking what your pet can eat? Visit our sister site SafeOrToxic.