While flea collars seem tempting to use, read the ingredients carefully and check the chemicals for safety at Scorecard, the Environmental Defense Fundís database of chemicals. According to the Cancer Prevention Coalition (CPC), ingredients on some flea collars are carcinogens, neurotoxins, or both. An effective and natural collar can be made using repellent essential oils.
Choose an absorbent collar for your pet, such as the widely available heavy-duty woven nylon collars. The collar will absorb essential oils, and no additional collar is needed. Essential oils that repel fleas and ticks include citronella, rosemary, and rose geranium. Buy only 100 percent pure essential oils, and using an eyedropper, put just one or two drops on the collar. Repeat each week. Some animals are very sensitive to the strong smell of essential oils, so start with just one drop and increase to two if they seem to tolerate the smell. If ticks are the biggest problem, use rose geranium; for fleas choose citronella if for a dog, but not for cats.
Pennyroyal shouldn’t be used around pets, especially pregnant pets.
Cats are sensitive to citrus, so avoid citronella.
Make sure not to get the essential oil in the petís eyes or directly on their skin.