Have previously Frontline ordered from our vet because it also helped fine. This year I ordered a Frontline pharmacies shipping. Hair lice were at 24 hours away, the flea circus remained. Then gone Bin after 3 days to my vet, have the problem described - the vet told me that the cat fleas become immune to Frontline and gave me another agent helped immediately. The very next day the pests of our Jule were away at least. Now we have only sporadically in the apartment and on the other hand must address.