Crystal,
I am a big supporter of Frontline, I use it on all my animals. What I do to protect the kids is put it on at night and I make sure I move their fur and get down to the skin. Also my vet told me to sprinkle Boraxo under the baseboards and on the carpets, leave it on for 5 or 6 hours or overnight and then vacuum it up. I also sprinkle it around the foundation of my home, it keeps the ants and bugs away. I also washed my floor with it and knock on wood it has worked beautifully. We have 2 large dogs, one of which is a Samoyed and the other a German Shephard, plus 4 cats, and 2 ferrets, so fleas will be a huge problem if we don't keep on top of things. As for your son, I hope your realize he can be allergic to their bites as well, my son and I are. Hope this helps.
Hugs,
T.