Technically, cinnamon isn’t toxic to cats in the same way that other strong-smelling foods like onions, leeks or garlic are. In small doses, cinnamon sticks or powder shouldn’t do any harm but we wouldn’t advise using it to deter cats in the garden.
You shouldn’t encourage pets to play with or chew on a cinnamon stick either because in larger doses it can cause sickness and irritation if inhaled or ingested. It can also trigger allergic reactions if it gets onto fur and absorbed into the skin. Irritation can occur on the paws, nose, eyes and mouth.
Cinnamon essential oils are toxic to cats. According to the Pet Poison Helpline website, essential oils are concentrated to create a much stronger and more potent smell or taste, and a cat can become very ill if it comes into contact with it.
Cats don’t have the enzyme to break down some of the compounds in their liver so they wouldn’t need much exposure to cinnamon essential oil for it to be toxic.