Is it toxic to dogs?
Hydrangea
Hydrangea arborescens (and other Hydrangea species) · Hydrangeaceae
Also called Hortensia, Hills of Snow, Seven bark, Bigleaf hydrangea, Mophead
Toxic to dogs
Severity: Mild
Yes. The ASPCA lists hydrangea as toxic to dogs. It contains a cyanide-releasing compound, but true cyanide poisoning is rare and the usual result is vomiting and diarrhea.
- Toxic parts
- All parts, Flowers and leaves (AKC points to these as holding most of the toxins)
- Toxic compounds
- Cyanogenic glycoside
- Where you’ll find it
- House and garden
- When signs start
- When true cyanide poisoning does happen, Merck says signs often start within 10 to 60 minutes.
Signs of poisoning
- Vomiting
- Diarrhea
- Depression or lethargy
- Drooling
- Gasping, collapse or seizures (rare, after large amounts)
Why it’s harmful to dogs
Hydrangeas are the pom-pom-flowered shrubs of summer borders, and the cut blooms are a favorite in vases and dried arrangements. All parts contain cyanogenic glycosides. When the plant is chewed or damaged, these compounds can release cyanide.
That sounds alarming, and it is the reason hydrangea is on the toxic list. In practice, the ASPCA says cyanide poisoning is rare and usually shows up as a stomach problem instead. Pet Poison Helpline adds that poisoning from this plant is reported more often in grazing livestock than in pets, and the Merck Veterinary Manual says serious toxicity in small animals is uncommon unless a large amount is eaten.
Dogs are exposed when they chew garden shrubs, snatch fallen petals, or sample a bouquet left on a low table. Puppies and bored chewers are the usual suspects.
If your dog ate hydrangea
Remove any plant material from your dog's mouth and keep them away from the shrub or bouquet. Watch for drooling, vomiting and diarrhea.
Call your vet, or ASPCA Animal Poison Control at (888) 426-4435 or Pet Poison Helpline at (855) 764-7661 (US; fees may apply), if your dog ate a good amount, vomits more than once, or seems weak, wobbly or oddly quiet. Gasping, collapse or seizures are an emergency: go to the nearest clinic right away. Outside the US, call your local emergency vet. Don't try to make your dog vomit at home. Tell the vet which plant it was, how much your dog ate and when.
Keeping your dog safe
Plant hydrangeas where your dog can't reach, such as behind a fence or inside a raised bed, and keep bouquets and dried arrangements up high. Sweep up fallen petals and prunings, since wilted material is just as unsafe.
If your dog loves to dig and chew in the borders, consider switching to pet-friendlier shrubs such as camellias or roses. A "leave it" cue and a supervised yard visit make a bigger difference than any repellent.
Dog-safe alternatives
Frequently asked questions
Can hydrangea really cause cyanide poisoning in dogs?
It is possible in theory, but the ASPCA says cyanide poisoning is rare and the typical result is a stomach upset. Large amounts are the concern, so call your vet if your dog ate a lot.
Which part of the hydrangea is most toxic?
Pet Poison Helpline says all parts contain the compounds. The AKC points to the flowers and leaves as holding most of them.
Are dried hydrangeas safe?
The sources do not say dried flowers are safe, so keep dried arrangements out of reach just as you would fresh blooms.
Written from veterinary sources by the Pawsplained editorial team. Not yet reviewed by a veterinarian; this is general information, not a diagnosis or treatment plan. Updated Oct 30, 2026. Editorial policy