you might talk to your vet about something called Program. Unlike Frontline, its a shot, not a gel or cream that you apply on the back of the neck. They do a shot once every 6 months and it protects from everything that Frontline does. I think it's 50 bucks for 6 months but don't quote me on that as I use Frontline, not Program. That way you don't have to worry about it causing breathing problems with you etc...

there really isnt any natural way to repel them. if there were, we wouldnt have them all over the place. ive always had dogs and grew up in dayton. well in dayton, we never had fleas! then i move down here and all 3 of my cats have gotten tapeworm and i have to keep lucy on frontline now. fleas are crazy rampant around here. maryland it probably gets cold enough over the winter to fully kill them but theyll still get bad. some dogs are just more susceptible to them than others.