Ok, it's frontline plus. I always get it at the vets office, but I think i've seen it at petco. It's a bit pricey, but worth it because it works. If she doesn't go outside, then you should only need one application and it will get rid of the fleas. The box says it lasts for 1 month, but my vet said if they aren't in a heavily wooded area it works for 2 (or 3, I don't remember) but they say wooded area because of ticks, and if she's not outside she doesn't really have to worry about that. But fleas can cause worms too, then that's a whole other issue to deal with, and it's not pretty. My parents had an awful time with their puppy.