I bought a hartz flea collar and i had my 2 yr old cat sitting next to me. As soon as i opened the package he freaked out over the smell and started running away. He is a total stanger to flea collars and its unsual for him to act that way, but nevertheless i didnt think much about it cause i figured since it was a scented flea collar, he just didnt like the smell. Anyways, i got the chance to put the flea collar on him and right away he went nuts. He began to roll on the floor rubbing his neck profusley and started drooling real bad. I freaked out and rushed to get the flea collar off but my cat was so spooked he kept running away from me. After a hour of chasing and trying to calm him down, the poor guy looked hit. Watery eyes, slight foamy drooling mouth, and just down right weak. I took the collar off, washed his body, and im hoping to god he will be ok! I googled side effects for flea collars and found this website. I had read so many stories and i hear the same thing, “why hasnt anybody sued this company, and how are they even in business”???? I feel the same way!