From the time Advantage came out I have never used anything else. I bought it from the Vet. and in about 24 hours all fleas are gone. From what I know the fleas spend time on pets only long enough to bite and get blood to feed on. Most time is spent off the dog. My experience years ago is the flea collars do not work. My Daughter gets some flea med.s for her Labs in pill form. Money well spent.