We absolutely understand your concern. We know you only want to give what’s best to your kitty. We would never include any ingredients in our supplements which posed a risk to pets. The leaves, flowers, and buds of the hydrangea plant contain a substance called glycoside amygdalin which has the potential to metabolize as cyanide. Research has shown that the amount of amygdalin that would need to be ingested for there to be any danger is extremely high. Like any substance, the toxicity is very dependant on the dose. However, Tripsy does not contain any hydrangea leaves, flowers or buds. The part of the hydrangea used in our supplements is the hydrangea root. As is the case with many botanicals, the roots have different properties from the rest of the plant.