Cats are more sensitive to essential oils than dogs and humans, so many veterinarians do not recommend using them with cats.  A cat has few liver enzymes that work to metabolize essential oils, which means they can pose a serious health risk.  Some essential oils, such as neem oil, lavender oil, and cedar oil are safer for cats.  You may be able to safely use these oils with your cat if you follow proper dilution instructions and make sure your cat does not ingest the oils.