Many essential oils, such as eucalyptus oil, tea tree oil, cinnamon, citrus, peppermint, pine, wintergreen, and ylang ylang are straight up toxic to pets. These are toxic whether they are applied to the skin, used in diffusers or licked up in the case of a spill.

Is eucalyptus smell safe for dogs?

But even though your dog can smell eucalyptus — whether it's from the tree itself or through an essential oil diffuser — it doesn't mean they should. Eucalyptus is actually toxic to dogs (and humans) when ingested, and it can cause also irritation when applied to the skin.

What essential oils are safe to diffuse around dogs?