Its supposed to kill the ticks within 24hrs i heard. we're having a terrible tick season where i am. we live in the woods and when i bring Lou Dog in, i'll look over at him and since his head is mostly all white you can just see the ticks crawling all over him. i took over 30 off him last night, and im sure i missed some. Hes been on frontline for months too. I HATE TICKS!!!