Will Rosemary essential oil hurt a cat?

For cats in particular, you need to be careful about what oils you use on them or expose them to because cats do not metabolize things the same way as dogs (or humans). This means that the liver in cats cannot break down or metabolize certain drugs, medications, and even some essential oils.

If you are interested in using essential oils for your cat, you should do so only as directed and/or supervised by your veterinarian. In general, the essential oils you should AVOID using with your cat include oils that are high in salicylates or phenols, such as: Basil, Cinnamon Bark, Clove, Laurus Nobilis, Melaleuca Quinquenervia, Mountain Savory, Oregano, Tea Tree, Thyme and Wintergreen.

BUT, lavender, copaiba, helichrysum, and frankincense are all SAFE.