Is Hydrangea Toxic to Cats and Dogs?

Q: Is hydrangea toxic to cats?

Mildly toxic to cats. Hydrangeas are toxic to dogs and cats because they contain cyanogenic glycosides, but cyanide poisoning is rare. Most pets only get vomiting, diarrhea or lethargy.

Q: Is hydrangea toxic to dogs?

Mildly toxic to dogs. Hydrangeas are toxic to dogs and cats because they contain cyanogenic glycosides, but cyanide poisoning is rare. Most pets only get vomiting, diarrhea or lethargy.

Hydrangea arborescens

Cats

🟡 Mildly toxic

Dogs

🟡 Mildly toxic

Short answer: Hydrangeas are toxic to dogs and cats because they contain cyanogenic glycosides, but cyanide poisoning is rare. Most pets only get vomiting, diarrhea or lethargy.

Think your pet ate hydrangea? call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435.

Signs to watch for

Vomiting
Depression (lethargy)
Diarrhea

Why it’s a problem

Toxic principle: Cyanogenic glycoside.

The ASPCA lists hydrangea as toxic to dogs, cats and horses. It says cyanide intoxication is rarely seen and that stomach upset is the usual effect.

Frequently asked questions

How much hydrangea is dangerous?

The ASPCA doesn’t give an amount. It says cyanide poisoning in small animals is very unlikely and that stomach upset is most common. Call your vet if signs are more than mild.

Other plants

Poinsettia
Fiddle Leaf Fig
Easter Lily
Hosta
Daylily
Peace Lily

Sources

ASPCA plant database: Hydrangea
ASPCA: Top 10 Toxic Plants for Pets

Last checked: 2026-11-11. General information, not veterinary advice.