I used Zodiac-brand flea collars once and instantly, both of my cats started foaming at the mouth. I took them off immediately and washed their fur. While it was scary, it didn't have any other consequences. That was the last time I ever used flea collars. It also made me wonder why I never thought how terribly uncomfortable they must be for cats: that stuff stinks.
I've heard of people using garlic pills to make a cat flea-repellent, but I would never do this. I know onion is terrible for both cats and dogs, and I believe even garlic can make them anemic. Sometimes, natural cures can be equally as dangerous as the pesticides. Scary article about garlic and onion toxicology in dogs and cats. I'd recommend that everyone be very, very careful about giving their cat anything, no matter how safe or natural it seems, or how many commercial websites promote it.
I've used Advantage a few times with no ill effect, but I still hesitate to use any flea treatments. Now I just try to keep them contained indoors in a flea-free zone; the chihuahua gets baths as needed. It seems to be working so far.
