Is Hydrangea Toxic to Cats and Dogs?

Hydrangea (Hydrangea spp. (Hydrangea macrophylla, Hydrangea arborescens)), also called hortensia, is mildly toxic to both cats and dogs.

Why

The ASPCA lists hydrangea as toxic to cats and dogs. Its leaves, flowers and buds contain cyanogenic glycosides, compounds that can release cyanide when chewed.

In practice, the ASPCA notes that cyanide intoxication is rare and the plant usually causes stomach upset instead: vomiting, diarrhea and depression. Pet Poison Helpline adds that cyanide poisoning from hydrangea is more often seen in livestock, which eat large amounts, than in pets.

How to recognize it

Hydrangea is a leafy shrub with large, broad, toothed leaves and big rounded or flat-topped clusters of flowers in blue, pink, purple, white or green. Mophead types have ball-shaped heads; lacecap types have a flat center of tiny flowers ringed by larger ones. It is sold as a potted gift plant and grown widely in gardens.

Signs to watch for

• Vomiting
• Diarrhea
• Depression or lethargy

What to do

• Remove any plant material from your pet's mouth and offer water.
• Call your vet if vomiting or diarrhea continues, or right away if your pet seems weak, breathes fast or collapses.
• Clear fallen flower heads and pruned stems from the garden.

Should I worry about cyanide if my dog ate hydrangea?

Usually not. Cyanide is the reason hydrangea is on toxic plant lists, but the ASPCA describes cyanide poisoning from it as rare in pets, and the typical result is an upset stomach. Pets rarely eat enough of the bitter leaves and flowers to reach a dangerous dose.

The exception is a very large amount, especially in a small dog. Pet Poison Helpline describes cyanide signs as vomiting, drooling, gasping, collapse and seizures. Any of those beyond simple vomiting means going to a vet immediately.

Does flower color change how toxic a hydrangea is?

No. Bigleaf hydrangea flowers turn blue in acidic soil and pink in alkaline soil, and gardeners often change the color by adding aluminum sulfate or garden lime. The plant and its cyanogenic glycosides are the same regardless of color.

The soil treatments are a separate concern. Keep bags of color-changing products, fertilizer and lime closed and stored away from pets, and keep dogs out of freshly treated soil.

Are dried hydrangea flowers in a vase still a risk?

Hydrangea heads are popular in dried arrangements and wreaths because they hold their shape and color. Drying does not make them non-toxic, and the light, papery petals are easy for a cat to bat around and chew.

Pet Poison Helpline notes that damage to the plant, for example by frost or crushing, can release free cyanide. Treat dried or frost-damaged hydrangeas the same way as fresh ones and keep them out of reach.

Pet-safe alternatives

Looking for something similar without the risk? These plants are listed as non-toxic to cats and dogs.

• Non-toxicAfrican violet
• Non-toxicRoses

Common questions

Is hydrangea poisonous to pets?

Cats: Mildly toxic. Dogs: Mildly toxic. Hydrangea is mildly toxic to cats and dogs. It usually causes vomiting, diarrhea and lethargy; true cyanide poisoning is rare.

Is it safe to keep hydrangea in a home with cats and dogs?

Yes, as long as your pets cannot reach it. Clear fallen flower heads and pruned stems from the garden.

What should I do if my pet chews hydrangea?

Remove any plant material from your pet's mouth and offer water. Call your vet if vomiting or diarrhea continues, or right away if your pet seems weak, breathes fast or collapses.

Which pet-safe plants can I grow instead of hydrangea?

African violet and roses are listed as non-toxic to cats and dogs.

← All plants

Sources

• Pet Poison Helpline. Hydrangea.
• ASPCA Animal Poison Control Center. Toxic and Non-Toxic Plant List (dogs, cats).
• Merck Veterinary Manual. Toxicology section.

If your pet has eaten a toxic plant, contact your veterinarian or an emergency animal hospital right away and bring a photo or piece of the plant. In the US you can also call the ASPCA Animal Poison Control Center at (888) 426-4435 or the Pet Poison Helpline at (855) 764-7661 (fees may apply).