My girlfriend and I recently adopted a cat from a shelter, and purchased a Hartz flea collar (the 2-in-1 brand) for it. The collar did not seem to harm the cat but gave me and my girlfriend (who live with the cat) horrible rashes. We checked with our doctors and with the vet, and they all believe that the culprit was the flea collar – since no other changes in our home have been made since we obtained the cat. The cat also has a clean bill of health from more than one vet (just to make sure we didn’t catch something from it). The rash still comes and go (for over two months now) and is extremely irritating – we are both taking allergy medicine and have obsessively and repeatedly cleaned the house and the cat to get the allergins out, but the doctor says the collar is designed to disperse the chemicals widely and it will probably be a few more months before it’s out of our home and systems. We haven’t contacted Hartz because we know that without a lawyer and extra medical expenses it would be impossible to get them to admit that the rash is the fault of their collar. Please investigate the chemicals they use in their collars and the effects of the collars on animals and humans before purchasing their products. Thanks for creating this site, and hopefully our story will prevent more people from suffering from horrible Hartz products.