Will It Poison?

Is Hydrangea Toxic to Dogs?

Caution

⚠️ Risky — depends on amount & dog

Hydrangeas are mildly toxic — they contain cyanogenic glycosides, but a dog usually gets GI upset long before a dangerous dose.

Hydrangea leaves and flowers technically contain amygdalin (the cyanide-releasing compound), which sounds terrifying but rarely plays out that way: the concentration is low and vomiting starts early, self-limiting the dose. Real-world cases are almost always a day of GI upset. Massive ingestions in small dogs are the exception worth a call.

What makes it dangerous: Cyanogenic glycosides (low concentration)

Symptoms to watch for

  • Vomiting
  • Diarrhea
  • Lethargy

What to do right now

  1. Water + bland food once vomiting settles
  2. Call your vet if a small dog ate a large amount or symptoms exceed 24h

Sources: ASPCA Toxic Plants Database. Educational reference — not veterinary advice.