Is Hydrangea Toxic to Cats?
Also known as: Bigleaf Hydrangea, French Hydrangea, Hortensia · Hydrangea macrophylla
What makes it toxic
Cyanogenic glycosides (hydrangenol and amygdalin-type compounds) in all parts, especially leaves and buds. Digestion releases small amounts of cyanide, disrupting cellular oxygen use.
Warning signs to watch for
Vomiting, diarrhea, drooling and lethargy within hours. Significant ingestion can progress to labored breathing, bright red gums, tremors and collapse.
What to do if your cat eats it
Remove material and call your vet after any chewing — dose matters with cyanogenic plants. Labored breathing or collapse means go to the ER immediately.
Common questions
Can a cat get cyanide poisoning from hydrangea?
A serious exposure can. Most cases involve small nibbles and mild GI signs, but large amounts release enough cyanide to be dangerous.
Are dried hydrangea blooms still toxic?
Yes — the glycosides persist in dried flower arrangements, a common winter exposure. Keep them off reachable shelves.
How quickly would trouble show?
GI signs appear within a few hours. True cyanide effects come fast after a large dose, which is why early vet contact matters.
More plants checked for cats
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.