well, not to alram you, but using Hartz is very very bad, it HAS poisoned cats in the past. If I were you I would get to washing that off ASAP and then see your vet about getting something like Frontline or Advantage for Fleas, they are much safer and IMO far more effective. Also, when I put this kind of stuff on my cats, I actually put it above the shoulder blades, basically in the middle of the back of their neck to be sure they can't get their tongue on it