This collar contains imidacloprid and flumethrin integrated into the collar’s structure for a slow, consistent release that kills existing ticks, fleas, and lice. We like that the collar’s ...

The Seresto Flea and Tick Collar contains imidacloprid and flumethrin, which are released in low concentrations over your cat's skin and coat to kill fleas on contact. The water-resistant collar ...

The collar's active ingredients, imidacloprid and flumethrin, are released in low concentrations over your dog's skin and coat to kill fleas and ticks on contact within 24 hours. You don't need to ...

The active ingredients in one of the leading dog flea collar brands are imidacloprid and flumethrin, while other brands contain deltamethrin or methoprene — or both — as the active ingredient.