I really didn't want to use any kind of chemical product on my dog, but after waging a losing battle trying to go all natural, I finally gave up and just used Frontline. I bought my Frontline Plus at the local Agway Feed and Seed store. 48 hours later, my dog is STILL itchy and miserable - and still covered with as many if not more fleas than before!When I called Frontline, I was told that the only REAL Frontline must be purchased through veterinarians and if it was NOT purchased through a vet, it is FAKE! I'm livid that I bought mine from a store that is a large chain and it's probably fake.I would caution anyone buying online - you may be getting a counterfeit product. My dog is miserable and I don't know what to do. I'm afraid to re-treat him with something else since he was just frontlined. He's on Sentinel which seems to be doing nothing to the flea population here either.......:(