D.E. is the only thing that finally killed the fleas in my apartment (inherited when I moved in; long story short, a flea bombing and 2 professional exterminations later, they still came back - one thorough treatment of DE and I haven't seen them since... not inside at least, except for when my dog was bringing them in from the yard).
Food grade is supposed to be safe to use on their coats, but it makes their coats really dry (as I found out when my dog was bringing in fleas from the yard this last year). I would do a thorough application of DE to the carpets, couches, etc., sprinkle some on their bedding (after washing everything), (and, be sure to vacuum up any loose powder afterwards) and use a monthly flea treatment on your dog(s) instead of applying DE to them directly. If it is still warm outside and you have a yard, you should probably also apply beneficial nematodes to the yard to kill any flea larvae out there that your dogs might be bringing in from outside.
The combination above works well for me to keep those nasty bugs at bay... if you can't use monthly flea treatments due to sensitivity, one thing that I have found that works well for spot treatments (I wouldn't bathe my entire dog in it) is a product called Lice Freee (http://www.licefreee.com/
). But, it's not specifically for fleas OR for dogs, so use at your own discretion.
Good luck! I hate those nasty bugs!!!