Are hydrangea leaves toxic to adults?

Hydrangea leaves are not considered toxic to adults, but they do contain a compound called cyanogenic glycosides, which can release cyanide when metabolized. While ingesting small amounts may not cause significant harm, consuming large quantities can lead to nausea, vomiting, or more serious health issues. It's always best to avoid eating non-edible plants. If there’s any concern about exposure, consult a healthcare professional.