yes i have to agree and endorse what u say, over the counter products can be harmful to your pet, my vet said they are actually toxic, use 'ADVANTAGE' its just a tube u squeeze on the back of their necks out of reach and it works wonderfully, FRONTLINE is another good product cost around seven dollars a tube, but worth it for the animals and your sakes, of course this is in new zealand, u may have other products just as good or similar over in usa no doubt.