"I am always hesitant to use any kind of product on my cats. I noticed my girls scratching, saw a flea and knew I had to do something. A friend uses Frontline for her dog, and suggested I give the cat formula a try. Ordered on Sunday, delivered on Wednesday, very fast shipping. I was a little concerned about using it on my girls as they had quickly scratched some sores on their necks and heads, so I called the Frontline toll free number and spoke with a vet tech, who assured me it would be ok. I also called my vet's office, and they also assured me it would be ok, and my vet's office informed me that Frontline is one of the products they recommend. I applied the Frontline Plus to my girls on Friday evening, and within 4 hours I started to see dead and almost dead fleas. It's Sunday morning and my girls are well on their way to being flea free. I suggest you also wash all of their bedding and yours, and go the extra step when vacuuming, and do a really thorough job including the furniture. I was also impressed with the product's easy to use applicator. It popped open and was easy to squeeze and apply. If your cat(s) have fleas, give this product a try. Ordering from Petco.com was easy, and they have an option for an alternate shipping address, and actual shipping was very fast."