Fleas hate the taste of the animals skin from the brewers yeast and garlic. However given the fact that you animals are all ready infested I would go ahead and do a flea dip on them, bomb the house with those bomb thingys and continue to give them the pills. I have used these pills with our animals for years, but we start prior to the warm weather season when fleas are a problem.
My cats love these pills so I give them more than the recommended amounts. It does take a while for these to completely go through their systems. hth. Marva