I had bad luck with Frontline also. Seemed to work ok for the first few months and then didn't keep up.
Best luck I've had has been with Bayer Advantage ii. Works great and keeps the fleas from setting up shop and quickly killing any that try to hitch a ride.
Pro tip, notice the pretty wide weight ranges and that all the sizes cost the same? Buy the extra big doggo size and some syringes, shake the tube and empty into a suitable container (I use an old pill bottle), and then dose it yourself using the syringe. Simple chart here-
http://startcowdog.homestead.com/Advantage-Dose-Chart.html . If you've got leftovers store in the fridge and just bring up to room temp and shake before dosing. There's no difference at all other than the size of the tube. If you've got any cats to treat you can still use the dog one and they're on the chart as well. There's no difference but the tube size, concentration and everything else is the same. For the chart I posted and if being used on or imo even around cats make sure it's the GREEN advantage ii and not the red advantix, which supposedly covers some more creepy crawlies but is highly toxic to cats. Personally I've never had an issue on dogs with the stuff supposedly covered by advantix but not advantage.
Also if you've got a bad existing population in the house, yard, etc you can apply every seven days while getting it under control so it's always at it's most effective. Personally whenever I've felt it necessary to do more than once a month I found every two weeks to be more than sufficient and I'd hate to think how bad it'd have to be to require going weekly to get things under control.
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