I agree with visiting the vet and getting prescription flea treatment. I used Advantage on my cats when I introduced a new kitten, who had fleas, to my household. Since I could not treat the kitten until she was older, I had to treat my adult cats in case they picked up fleas from her. I only had to treat them for three months with the prescription brand (my cats are indoor only.) After that, the fleas were gone and have not come back to this day, even two years later.
