Are hydrangeas toxic to cats?
Also called: hydrangeas, Hortensia, Hills of Snow, Seven Bark, Hydrangea arborescens
Toxic
Usually causes stomach upset; it contains a cyanide-forming compound.
Yes. Hydrangeas are toxic to cats. They usually cause vomiting, diarrhoea and lethargy. They contain a cyanide-forming compound, but cyanide poisoning is rare.
Signs to watch for
- Vomiting, depression and diarrhoea. Cyanide poisoning is rare.
Where this comes from
ASPCA Animal Poison Control
Toxicity: Toxic to Dogs, Toxic to Cats, Toxic to Horses
Read "Toxic and Non-toxic Plants: Hydrangea"
Checked 9 October 2026
Merck Veterinary Manual
Common houseplants and ornamental plants that contain cyanogenic glycosides include the following: Cercocarpus spp (mountain mahogany) Hydrangean spp (hydrangea)
Read "Houseplants and Ornamentals Toxic to Animals"
Checked 9 October 2026
Where this comes from
ASPCA Animal Poison Control
Toxicity: Toxic to Dogs, Toxic to Cats, Toxic to Horses
Clinical Signs: Vomiting, depression, diarrhea. Cyanide intoxication is rare – usually produces more of a gastrointestinal disturbance.
Read "Toxic and Non-toxic Plants: Hydrangea"
Checked 9 October 2026
Merck Veterinary Manual
Common houseplants and ornamental plants that contain cyanogenic glycosides include the following: Cercocarpus spp (mountain mahogany) Hydrangean spp (hydrangea)
Read "Houseplants and Ornamentals Toxic to Animals"
Checked 9 October 2026
Where this comes from
International Cat Care
If you’re concerned your cat has come into contact with any of the substances listed, contact your veterinary team immediately
Checked 9 October 2026
Where this comes from
ASPCA Animal Poison Control
Clinical Signs: Vomiting, depression, diarrhea. Cyanide intoxication is rare – usually produces more of a gastrointestinal disturbance.
Read "Toxic and Non-toxic Plants: Hydrangea"
Checked 9 October 2026