This spray was recommended to me by a vet for use on week-old kittens. I was sceptical, because the kittens were so tiny and no other product was indicating suitability. We did not spray it directly onto the kittens, we sprayed it onto our hands and rubbed it over them. Flea problem no longer a problem! (You do have to do a repeat 'rub' to catch hatchling fleas.)
Awesome service/delivery/price from Pet Plus, too.