I've had cats for years, and never have I encountered more resistant fleas. As soon as I see a flea, I treat everything. Of course, that's exactly what I did last month. We started with Sentry drops, which seemed to work for a few days. Then they were back. We started bathing the cats once a week with Dawn soap, scrubbing them down and letting the fleas drown. We treat and vacuum the carpet, treat the couch and mattress, and wash our sheets and blankets once a week. When a month had gone by, I went out and bought Frontline. The fleas ignored the Frontline. It's like I never used it. I don't even know where to go from here, and unfortunately, I'm allergic. I've spent the last two weeks fighting my hives too. Any suggestions would be great.