Apparently, this cheap cat flea product is unsafe as there appears to be far too many complaints about it and instances of cats being poisoned by. It is a cheap product and that may be one reason why it tends to poison cats. It is not a drop on treatment but a spray it appears to me. This means it goes all over the coat and into the skin. I would never use such a product by the way. I would never use any cat flea product unless I really have to. Comb with a flea comb first and keep an eye on fleas. Kill them by hand if possible. Keep your house clean. Always take preventative action against fleas getting into the home. I think flea treatments which are based upon insecticides are inherently very dangerous and can cause neurological damage. All insecticides are poisons and they are nasty poisons.