Bests & Worsts Reviews from Amazon

I put the collar on my adult male cat and after about 48 hours he starting exhibiting tremors in his head. His head and ears were twitching. Both of the main ingredients in Seresto (Imidacloprid and Flumethrin) list tremors as a possible side effect in addition to a number of other things. I removed the collar and within 12 hours the tremors stopped.